BIOLOGY 101 FINAL

Understand how genotypic variation leads to phenotypic variation, how phenotypic variation may lead to differential survival and reproduction, and how differential survival and reproduction leads to the evolution of a population

ALLELES is the official phrase we use for one of these heritable units. An ALLELE is a version of a given gene. So the gene that controls cat coat color is the gene, and the ALLELES are the different heritable unit types. So there is a brown coat color allele and a black coat color allele in cats. In the pea plants there is a purple flowered allele and a white flowered allele at the same gene. So the same gene flower color, can exist in two different versions either in the purple flower versions or the white flower version. So variations of a given gene different mutations different variations of a given gene are what we all ALLELES. So you various alleles at each of your genes. All of your chromosomes are covered in genes like all the little chunks of chromosomes are genes and you have two copies of each of them remember, one version of each chromosome from your mother and one version of each chromosome from your father. And so at each of the genes on a chromosome its going to have another copy of that same gene on the other chromosome, but there might be a slight variation and that slight variation is what we call ALLELES. So you may have one brown eye colored allele and one blue eye colored allele, and those two alleles together, the relative dominance or interaction between those two is what controls your trait the eye color you actually have. We have two alleles for every gene, every single one of our genes we have two alleles. You may have the same kind of allele on your two different chromosomes for a given gene, but you still have two copies of them. Thats humans, humans are diploid so we have two versions of every chromosome. And every chromosome has the same kind of genes and those different versions of this genes that are present on each of this two chromosomes are your two alleles. So for every given gene that exists in the human genome, you have two alleles, they may be different they may be identical, but you have two alleles for every given gene. Those alleles those different alleles are made of DNA. These gene versions are made of DNA, DNA codes for RNA then MRNA, that MRNA then leaves the nucleus of the cell goes out to the ribosomes of the rough endoplasmic reticulum and is translated into a protein. So every allele every gene variant, at the end of this cycle produces a protein. And different kinds of alleles, if theres a slight variation in the DNA sequence in the sequence of nucleic acids in the gene in your DNA in your chromosome, that may lead to a different kind of protein produced here at the end, and so a different kind of allele a different kind of DNA strand may produce a different kind of protein that will then have some different kind of effect in your body then in someone that doesn't have that allele. So we see this in our eye color. The brown eye allele is a gene variant here that produces a brown pigment. That brown pigment is a protein. And so people with brown eyes has a specific DNA sequence that encodes for MRNA which makes a particular brown pigmented product, that goes into your eyes and your eyes appear brown. So these different gene ranks these different mutations in the DNA that leads to different kinds of alleles get carried through the different kinds of proteins and that then can cause some different kind of function some different kind of appearance different kind of behavior in your body. Phenotype is a great importance and the reason that it is because although we can look at molecules we can look at chromosomes we can look at DNA strands at genes at individual proteins, the world does not look at organisms on the molecular level. The wold interacts with us on our organismal level on our phenotype. So the way that we interact with the world is the way that our phenotype is shaped, not necessarily our genotype, but our genotype controls what our phenotype is. So we've got this diversity of dogs, this is called phenotypic variation, we have a spectrum of phenotypes. And this spectrum of phenotypes of little dogs to big dogs is controlled atleast in part by their genotypes. Big dogs have big dog alleles and little dogs have little dog alleles. If we have Differential Survival that means that different organisms on this spectrum survive at different rates, then something interesting might happen. So lets say for example you have all of the dog food in the world is inside a warehouse, and on that warehouse door is a dog door that is small. The little dogs will make it through the dog door but the big dogs do not. Therefore the bid dogs starve and die. So we have some environmental condition that is interacting with the phenotype the physical of our population of our dogs and it wipes out the big dogs, and all thats left is the little dogs because they're the only ones that can fit and get food. And so if our big dogs die and all we're left with is our small dogs, then in the next generation of dogs everything is going to look different than if we had all of the parents still present including the big dogs. If the big dogs are still present we would have some larger dogs in our next generation as well. But since all those big dogs got wiped out, all thats left to reproduce is these little dogs who reproduce little dogs in our net generation. This is phenotype, we are looking at how a phenotype is passed down from one generation to the next here with a little bit of mortality and this is related to the genotype. Remember this phenotype this size is controlled by genes, the size of these fogs is controlled specifically by what kinds of alleles they have then we might have something interesting going on at the phenotype level in addition to this genotype level. So big dogs all have big dog alleles, thats how we got a big dog in the first place. And our really big dogs they might be homozygotes for the big god alleles. Our medium size dogs might be heterozygotes they have one big dog allele and one small dog allele so we would have to co dominance thing going on a blend. And then our small dogs have got two small dog alleles. If we wipe out and kill all of the large and medium size dogs, what happens to the large dog alleles in this population? The large dogs have the large dog alleles but if we kill them all then the large dog alleles get removed from the population. And so our large size allele decreases and the small dogs are the only ones left. The small dogs got small dog alleles and they're the only ones that are passing on their genes passing on their alleles to the next generation. So the only thing that is left in this population are small dog alleles. And so we get a Relative Increase in the frequency of small dog alleles. Thats Differential Survival. So different individuals in our population survived, and that survival was related in some way to their genotype the genes that they had were in some way related to the phenotype allowed them for better survival than other individuals in the population. Starting with our same population of dogs we're looking at Reproductive Success/Differential Reproduction. If we have a population like this where some individuals are better at reproducing, can produce more offspring maybe better quality offspring offspring that are better able to survive, then that can also lead to something interesting. Nobody is dying, but we got differential reproductive success. For example out of all the dogs only one breed of dog is reproducing way more than the other breeds of dogs. They're making lots and lots of babies and everybody else is not. So whats the consequence? If most breeds produce very few puppies but one breed is producing lots of puppies. Whats going to happen throughout time to the relative frequency of the breeds that are producing as much alleles and the breed that is producing a bunch's alleles? Our non labrador alleles decrease in relative abundance and our non labrador alleles increase in relative abundance.

Understand how alcohol can both be good and bad for cardiovascular health

Alcohol affects several neurotransmitters. Alcohol affects Serotonin which is mood maintenance, as well as Endorphins which are the things your body produces to make you feel good the ones that make you feel like everything is okay, when you experience pain, pain tells you to stop doing whatever it is that you're doing, but then you need to calm that pain down, so endorphins are one of these neurotransmitters that help dim the pain. Other neurotransmitters that are important are Glutamate and GABA, these two are antagonist neurotransmitters. The glutamate is an excitatory neurotransmitter, it tells other neurons to start sending signals, doesn't matter what the signals are just start sending signals. And the GABA tells other nearby neurons to stop sending signals, to stop communicating with other neurons. So what alcohol does in your body in your brain is it releases serotonin, and it releases endorphins. This is why you get happy and get relaxed when you drink. The other two the GABA and the glutamate, the GABA the inhibitory gets stimulated, so alcohol mimics GABA by alcohol telling neurons to calm down and to stop sending signals. And alcohol blocks glutamate which is the one that tells neurons to communicate with eachother. Glutamate is really important for the formation of memories, because you're using glutamate neurotransmitters as you're creating memories. So alcohol blocks glutamate blocks the ability to form memories, and is why if you drink a large amount of alcohol you blackout and don't remember anything because the glutamate is not present and functionable. So thats whats happening biochemically in the brain from alcohol. Alcohol can be good for you, can have some serious positive benefits on the body, one of those benefits is that alcohol is good for your cholesterol. It lowers your bad cholesterol your LDL low density lipoproteins, AND also increases your HDL the high density lipoproteins the good cholesterol. LDL is bad for you because it may cause atherosclerosis and embolism. LDL is the kind of cholesterol that gets stuck in arteries. This is what blocks your blood vessels. Atherosclerosis is the hardening of your arteries hardening of your blood vessels, caused by the accumulation of plaques of this LDL cholesterol and blood clots that get bound up. If that breaks free, goes downstream and plugs an artery, you get an embolism. The function of the HDL the good cholesterol is to go around and scrub up your arteries clean of these LDL accumulations. The consumption of cholesterol, which is a lipid, does stimulate the production of lipase. But lipase's job is to digest lipids, and although cell membranes are made up of lipids of phospholipids, the part thats exposed to the outside of a cell, is the hydrophilic part of the phospholipid, not the lipase might target which would be the tails that are on the interior of the cell membrane. Alcohol has effects on cholesterol, on the good and bad cholesterol. Yes alcohol can be good for your body, particularly good for your cardiovascular system and it seems to be a linearly increasing benefit of the good cholesterol the more that you drink. That is not to say that alcohol is only good for your body. In fact there are bad things for your body and your cardiovascular system that alcohol can cause. Alcohol is toxic it kills cells, which is what makes hand sanitizers work, they're killing bacteria that are on the surface of your hands. So if you're drinking excessive amounts of alcohol that can kill you too. That can kill your body's cells. What happens when you drink a lot of alcohol is your blood alcohol content goes up and then those cells that are lining the blood, the cardiovascular system, like your arteries your veins, those blood vessels, are made of cells and the alcohol thats in your blood can kill those cells. And the result of killing damaging those cardiovascular cells is some of the problems that we were hoping to avoid by drinking alcohol and raising our HDL in the first place. We get heart problems where our heart is beating irregularly, which is a cardiac arrhythmia. Hypertension which is high blood pressure, stroke is possible, atherosclerosis is also possible with high alcohol consumption. Holiday Heart Syndrome is a result of high alcohol levels accompanied with some stress that combination leads to an increase in cardiac problems. More strokes, heart attacks, heart problems due to combination.

GENETICS & EVOLUTION Understand the difference between chromosomes, DNA, genes, and alleles

CHROMOSOMES Haploid is the number of different kinds of chromosomes. Humans have a diploid number of 23. So there is 23 different kinds of chromosomes. Each chromosome has 100s to 1000s of genes. Our 23rd chromosome is our sex chromosome-XY. While others are numbered 1-22, our 23rd is labeled XY. The ploidy is the number of copies of each of those chromosome types. Cartoon of human chromosomes, this individual has only one copy of each of those 23 different kinds. So the haploid number is still 23, and there is one different version of each of those 23 chromosomes. So we call the ploidy here 1, or abbreviated 1N, so this means we have 1 copy of each of the N, the haploid number, of chromosomes. So this organism would be a 1N cell, also known as haploid. Haploid meaning we just have one copy of each of the different kind of chromosomes. If you have two copies of each chromosomes, which is the normal condition for humans, we have 23 different kinds and two copies of each of those kinds, we call this Diploid. The ploidy is 2, or 2N. Meaning we have two copies of each of the different kinds of chromosomes. If you have three copies, we call that triploid. 3 copies of each of the 23 different kinds of chromosomes. Humans only go up to triploid. Much variation beyond that means the human does not survive. In summary, the haploid number is the number of different kinds of chromosomes, abbreviated with the N, and the ploidy is the number of different copies of each of those different kinds of chromosomes. So (2N) the 2 in this case would be the ploidy, this organism is a diploid, it has 2 copies of each of the different chromosome types, this is a diploid organism. Humans have a haploid number of 23, with a ploidy number of 2, meaning we are a diploid with two copies of each of the 23 different kinds of chromosomes. So a total of 46 chromosomes. So that is what is going on inside of the cell, the physical chromosomes in your cells. Genetics, so A little bit of quick review, chromosomes these physical structures inside the nucleus of your cells, are very large DNA molecules. DNA is made up of nucleic acid chains. If we zoom in on one section of DNA, this little chunk with its specific code of nucleic acids, is called a Gene. And a gene codes for something, its a specific unit of DNA that tells your cell to do something. How it does that is by encoding for a specific protein, so we got our uncles acid here the gene, that then is translated into an amino acid chains which form unique protein types. So one specific gene will then code for and produce one specific type of protein. And then those proteins go on and do something in your body. So some of the proteins we talked about are being pumps, we talked about membrane proteins that allow to transport ions and things across cell membranes. But other proteins can be involved in controlling your behavior controlling your appearance, controlling the function of your body. Essentially all of the things that we do, the ways in which our bodies function, are all controlled by proteins. And those proteins are produced as a result of the DNA code the sequence of nucleic acids in our DNA that encode for specific protein types. And if two different individuals have two slightly different sequences of DNA, then thats going to encode for two slightly different proteins, and those slight differences in the proteins may result in slight differences in the individuals. We talked about DNA as a transmittable information molecule. And we talked about cell division and how different chromosomes are passed in both mitotic cell division, how you get a perfect copy and of chromosomes of daughter cells and also in meiosis and subsequently fertilization where we get a transmission of half of each parents chromosomes into the offspring. That DNA is heritable. So we have DNA in your chromosomes that would be put into your gametes, if your gametes combine and fertilize with someone else's gametes you have one offspring individual, and that offspring individual would have some of your DNA. So that DNA is heritable from one generation to the next. And because DNA encodes for specific proteins that change our body's function change our body's behavior and change our body's appearance, we also see heritability of characteristics. You can see physical similarities between the great grandmother, the grandmother, the mother, and the daughter. Those physical similarities are the result of genetic similarities. So transmission of specific codes of DNA that the great grandma had, she passed to her offspring, who passed to her offspring who passed to her offspring, so we can see that manifesting of physical appearance. You look like your ancestors because the DNA that your great grandparents had gets passed down through generations to you. Bunch of what we know about heritability about about how genes are passed down how DNA chunks are passed down from generation to generation started with Gregor Mendel and his peas and his experimental crosses, particularly focusing on the flower color of these peas. (cont. on flashcard after next one)

Understand the cause and consequences of climate change

CLIMATE CHANGE is here, climate change is accelerating, and some of the major impact of climate change, we're just starting to see in our world. And the major impacts of climate change in our world we are just starting to see. And those changes those impacts are going to be accelerating through time to the point in your lifetime where these changes are going to become very manifest very apparent. Climate change starts with a good thing. Climate change is based on the retention of solar energy on the planet. We have an atmosphere we have air and other gases in our atmosphere and one of the functions of our atmosphere is to track solar heat. If we didn't have an atmosphere if we didn't have greenhouse gases in our atmosphere, earth would be cold, we wouldn't have warmth. How the s works is that we have solar radiation thats coming into the earths planet its hitting the surface but then the earth traps that heat in the atmosphere. So it prevents that heat from leaving the atmosphere. So these greenhouse gases trap solar energy within our atmosphere where we can then be warmed up by it, thats a good thing that allows light to exist in hand allows us to exist. The problem of climate change is when we increase these greenhouse gases. Greenhouse gases are what do this heat trapping. They function like the window panes on a greenhouse, greenhouse window means allows light to come in, that light is then trapped inside the glass as heat and heat cannot as readily pass out through the glass as light can come into glass. So these gases are clear they allow solar light in, but they don't allow thermal heat out. Thats a good thing, UNLESS you get too many of them. And this has been our problem with climate change, trapping too many of these greenhouse gases in the atmosphere, retaining too much solar heat. Our common greenhouse gases are carbon dioxide, primarily carbon dioxide, but also water vapor and methane. These are our three greenhouse gases, too much of these things in our atmosphere leads to too much heat retention, leads to all manner of unusual things in our atmosphere and consequences of that on everyone else. Greenhouse gases come from a number of sources. All of these are combustion related, it can be burning things one of the byproducts of carbon dioxide. We've got industrial combustion, your car produces carbon dioxide. We also has some other interesting things like cows which burp and fart out methane which is another potent greenhouse gas. Carbon dioxide is the bulk of the greenhouse gases, most of the greenhouse molecules that are trapped in the atmosphere are carbon dioxide molecules. The high amount of carbon dioxide molecules trapped in the atmosphere, what this has done to our planet is by more of these greenhouse gases, we have more solar heat, and so our plane, the global temperature, on average has warmed up over that period of time. The arctic is particularly affected in terms of increasing temperature, some places are also getting particularly cooler like Washington DC, but in general if we look at global pattern, if we look at the way temperature has changed in the world is increasing. As a result of particularly carbon dioxide, but also other greenhouse gases production by human effects. All of the highest average temperatures have occurred in the past couple of years. 2016 is the warmest globe we have ever measured. We are definitely seeing the EFFECTS of the greenhouse gases in the atmosphere. In results some organisms are either dying or having to move. So species lost and species migration moving out into other regions. One of the other interesting things thats happening with climate change is not a temperature related phenomenon, but its a carbon dioxide related phenomenon. CO2 dissolving in water produces carbonic acid, and as an increase in hydrogen ions that are in water say in an ocean, that drives pH down. And so as were putting more carbon dioxide into our atmosphere, that carbon dioxide dissolves into the oceans, binds with water, and forms carbonic acid, lowering the pH of the oceans. Lowering it not a ton, but a little bit. Coccolithophores are a big chunk of those oxygen producers in the ocean, the shells that are surrounding them are made of calcium carbonate. That is the same structure of that of chalk, calcium carbonate is soluble when pH drops, and so one of the concerns of this increase of carbon dioxide and lowering of the pH of the oceans, is that these chalky organisms Coccolithophores will no longer be able to survive, thats troubling for us in the production of oxygen. This same basic idea of carbon dioxide combining with water and lowering the pH is also something that you are familiar with from within our bodies. So the organ system that is frequently dealing with this carbon dioxide related acidification is our Respiratory System. Carbon dioxide produced by your body gets into the blood, and then in result of that acidification of the blood, your blood acidifies lets say from a pH level of 7.4 to 7.2, and in what results is your hemoglobin delivers more oxygen to your tissues, drops more oxygen off into your bloodstream. We are made of organic chemicals just like all other life, we have organ systems just like all other animals, we evolve like all other living organisms, and interact with our environment and other species like all other organisms.

Understand the role of pumpkin pie in fighting off free-radicals

Cinnamon is where a lot of the benefit of pumpkin pie spice comes. All of the spices in pumpkin pie- cinnamon, ginger, nutmeg, cloves, allspice, are good for your body in one way or another. The mechanism by which these work by getting rid of this things called Free Radicals. Free radicals are atoms are molecules that don't have enough electrons. Molecules want to have the right number of molecules they don't want too many, they don't want too few, and free radicals are a group of molecules that don't have enough electrons they're missing one electron and they really really want that electron. And what they'll do is they'll go around to other atoms other molecules and rip off their electrons. By doing so, they severely alter the function of those other molecules. They're making those other molecules charged when they aren't, or they're making them non charged if they were, they're destroying the function of those molecules. And the functions of those molecules is really important to the function of your body. So you got a lot of free radicals in your body ripping apart molecules, thats going to change the unction of your body the function of your cells. Free radicals are a normal thing, this happens as a normal side effect of cellular metabolism. Your cells are metabolizing, and free radicals are produced as a normal side effect. If you don't get rid of them they can destroy your cells functionality. As you age your body produces more free radicals those free radicals are operating on your body, your skin cells get weaker they get looser you get wrinkles and bags and things, free radicals are to blame for that. The fight against free radicals is fought by Antioxidants. Free radicals tend to be oxygen based molecules, and so an antioxidant is one that is fighting against these oxidizing molecules. So an antioxidant is an atom or molecule thats got an extra electron, and it goes around, finds these free radicals, gives them this extra electron that this antioxidant doesn't want, and now that free radical is happy and our antioxidant feels like it has done a good job. If you have these antioxidants in your body you're not experiencing these cell damages, you're not falling apart and aging. We get antioxidants in some of the pumpkin pie spices. So cinnamon, cloves, these are great antioxidants, we find them in pumpkin pie spices. In addition to the antioxidant powers of cinnamon, it also modulates the amount of blood sugar, of glucose, thats entering into the bloodstream. It seems to do this by modulating how fast the stomach is releasing food blobs into the intestine. So the more cinnamon you have, the slower the stomach is releasing those blobs and so the amount of sugar thats entering your system gets spread out gets put into your blood slowly so that your body can respond to the produced insulin to keep your blood sugar at a more level place.

Understand generally how hormones control the labor of childbirth

During labor, on the mothers cervix on are Stretch Sensors. So one of the sensory receptors that people have are these Cervical Stretch Receptors. And when the babies head rests on the cervix, that applies pressure to this circular muscle that holds this cervix closed and as that babies head is pressing down, that stretches the cervix out. And those stretch sensors receive that stretching stimulus, and send nerve impulses to the brain. So the brain and particularly the hypothalamus and the pituitary glands in the brain receive these messages, and the pituitary gland releases Oxytocin. This is a HORMONE produced by this endocrine organ the pituitary gland. This oxytocin travels to the uterus, which is the big sac thats holding on to the baby, and importantly its a very big muscular sac. And this big muscular sac of the uterus receives this hormone oxytocin and begins contracting. So muscle cramps is essentially whats happening in the uterus, the uterus is cramping the muscles are tightening and holding to squeeze the baby out of the uterus. Those contractions push the baby down further, theyre squeezing, making the uterus smaller, now the baby has only one exit option and thats out through the cervix and so the baby head stretches the cervix even more. And that additional stretching of the cervix feeds back into the cervical stretch sensors again. We've talked a lot about hormonal feedback and this is a hormonal feedback loop. Its not a reflex arc. A reflex arc is like if you go to the doctor and the doctor hits your knee and as a reflex your leg shoots up, thats just a nervous system thing, that does not involve hormones. Oxytocin here is a hormone. We've got a nervous system and a hormonal endocrine system interacting. We start off here by stretching the cervix, that causes the production of oxytocin which causes contractions, which then produce more stretching of the cervix, and so this feedback into itself the more oxytocin thats released, the more stretching that occurs, the more stretching that occurs the more oxytocin thats produced. And so this is a POSITIVE FEEDBACK LOOP, this is one of the very few hormonal positive feedback loops, all the other ones that we talked about are negative.

Understand why fat-soluble vitamins can be easily overdosed, but water-soluble ones are more difficult to overdose

Fat soluble vitamins are hydrophobic, ones that do not dissolve in water but can dissolve in lipids. These are the Vitamins A, E, D, and K. The water soluble vitamins in general are the B complex vitamins and theres a handful of B vitamins. All the B vitamins and vitamin C are water soluble vitamins. They're hydrophilic, they can dissolve readily in water. Vitamin A is beta-carotene. You find vitamin A in relatively orange foods. This vitamin A is a part of your immune response so its involved in your proper immune function. Vitamin A is also involved in the reading of your DNA. So when little snippets of your DNA are translated into RNA, for then later use for protein production, you need vitamin A to help facilitate that translation. Vitamin A is also critical in your vision. The proteins that are in your eyes that are receiving light stimulation that are receiving the light thats coming in and telling your brain something about what you're seeing, can only be formed if you have vitamin A. So you need vitamin A to be able to see. There is a problem with fat soluble vitamins though, and the problem is overdosing on them. So you can eat a ton of carrots (vitamin A/sight), and your body will retain that beta carotene, and thats what makes your skin turn orange. Because these fat soluble vitamins do not readily dissolve in water, they are not readily excreted by the kidneys. So the kidneys remember, you've got your blood plasma is flowing through that glomerulus through those holes in the capillaries in the kidneys, all of that blood plasma is then getting filtered, selective reabsorption is happening, but that is only water soluble things that can go through the kidney efficiently. Fat soluble things, these hydrophobic vitamins like vitamin A, vitamin D, DO NOT get well filtered by the kidneys. And so when you take those fat soluble vitamins in, your body has to do something with them like build your visual proteins, you cannot easily excrete these and the downside of that is that you can overdose on it. So the fat soluble vitamins are ones that you need in small amounts but if you take too much of them they can start being a problem. They're a problem primarily in the liver. Its the livers job to deal with fat storage, its one of the places you store away fats and cholesterols. And if you get too much fatty built up in the liver, the liver stops functioning as well. So if you're overdosing on these fat soluble vitamins, your liver function can decrease. Water soluble vitamins taken in general as well as excess can dissolve in your blood plasma, that blood plasma then leaks out into your kidneys, and then is excreted.

Understand the benefits of sexual and asexual reproduction

Humans don't use asexual reproduction, we are unable to reproduce asexually. Individual cells in our body reproduce asexually, but we cannot produce a whole new human asexually, we have to use sexual reproduction. Asexual reproduction involves just yourself, and you're making copies of yourself. Sexual Reproduction produces more variability between individuals than asexual reproduction does because the offspring are different. That is because the parents are cutting their ploidy in half than mixing them together. Asexual is favored under stable conditions, the reason is, if you got stable conditions, lets say the bacteria that is living on this countertop here where the temperature is always about the same, the humidity is always about the same, this bacteria lives well here. If it didn't live well here it would die. So all of its asexually reproduced offspring have the same genetic code, the same genetic information, and the same ability to exist in this environment. If this environment changed, lets say that the room got filled with water, this bacteria may not survive very well in this environment, and if all the bacteria are the same, genetically identical, all of them will die of that genetic code is not good for that environment. In a very variable environment, a lot of genetic variation, which you get in a sexually reproducing population, is going to give that population as a whole a better chance to survive. Because if you're blending all the genes together, you might have one combination of genes in these organisms that can survive both right now as well as when this room gets filled with water. If you got very low population density, that means it is unlikely that you'll find anybody else. As a sexually reproducing organism, you need a parter to reproduce with. So if there is nobody else around, you can't reproduce. Therefore only asexual reproduction works if the population density is very low.

Understand the consequences of macronutrient imbalances

If you're eating a marathons worth of pasta everyday and not running a marathon everyday, your energy input may exceed your energy expense, your energy output. If thats the case you're going to start storing all those macronutrients in your lipid reserves, in your carbohydrate reserves, and if that persists for too long the end result is OBESITY. STARVATION AND OBESITY are imbalances of energy input and energy output. Obesity is larger input than output. An imbalance on too much input. Starvation and malnutrition is too much energy output with not enough energy input. Not enough calories coming in for all the energy being used. If you're starving, if you're not getting enough food input, enough calorie input. Your body first goes to its lipid reserves. You've stored all that fat in the past for the function of mobilizing it when you need it, when you're not getting enough energy and calories. Those triglycerides are there so that u can use them when you're not getting enough food. But if you exhaust those lipid reserves, the next best place your body can go is to protein metabolism. The muscle and fat has been digested away in a starved person by their own body. The body is going to those reserves, protein reserves, the muscles, to liberate ATP to function and power the body overall. Energy imbalances can lead to weight gain and weight loss. The reason why we don't gain so much weight from the massive amount of food we consume in a year is because the food is being converted into energy and being burned away.

Understand the processes and consequences of mitosis and meiosis

MITOSIS is ASEXUAL cell division. The goal of mitosis is to make an identical copy of your cell. So the goal of this cell is to make two cells that are identical to this parent cell. The first step in mitosis/cell division is to make a copy of the DNA. What we end up with is two diploid cells, these daughter cells have two different copies of the one chromosome (chromosome #1), which is the same condition that the parent had. The parent cell had two copies of chromosome 1, the daughter cells each have two copies of chromosome 1 and they are identical to the parent. This is how your cells ought to behave when you're growing. As you're growing any new cells in your body this is the process that your cells use; mitosis. And the goal is; you have one parent cell, it splits into two daughter cells, and those daughter cells are identical to the parent cell. Unless there is a mutation, if there is a mutation that is when we get problems like cancer. But assuming there is no mutations, we get two identical daughter cells from one parent, these daughter cells are identical to eachother as well as the parent. This is how your cells divide, this is how bacteria divide, this is also how some multicellular organisms divide- things like algae, fungi, etc. Asexual reproduction, you only need yourself and the offspring is identical to the parent. SEXUAL REPRODUCTION you cannot do by yourself. We need MEIOSIS. Meiosis is a different kind of cell division that results in a ploidy reduction. This is how we produce gametes, and those gametes are going to have half the ploidy of the parent cells. So if we start with diploid, our gametes at the end are going to end up haploid. Starts off the same way as mitosis, we start off with our unreplicated chromosomes, those get replicated, we get replicated chromosomes now, but the big difference is the way that those chromosomes separate when the cell divides. In mitosis, each of those replicated chromosomes gets pulled apart they separate from eachother and one half of that replicated chromosome goes to one side of the cell and the other half goes to the other side of the cell. In Meiosis, there are two separate cell divisions and in the first cell division, rather than these two copies that are attached, separating and pulling apart to different daughter cells, the two different copies of chromosomes one, so our blue copy and our red copy, they separate from eachother, but those chromosomes stay replicated and at this stage we got a reduction in ploidy. We started off here as diploid- 2 copies of chromosome 1 and now here we have one replicated copy of chromosome 1 and the other replicated copy of chromosome 1. So we've cut our ploidy in half, gone from a diploid organism into a replicated haploid organism. And then the second cell division of meiosis looks like mitosis in that that this replicated chromosome gets broken apart and one half going to each of the two daughter cells. So we start with one diploid parent cell, we go through two cell divisions and end up with four haploid daughter cells at the end of meiosis. These haploid gametes-these haploid daughter cells at the end of meiosis are NOT identical to the parent. They are different to the parent cell. So we start with a diploid parent cell, our goal in meiosis is to cut the ploidy in half, we go through meiosis, we cut the ploidy in half, and we're going from a 2N into a 1N, a haploid gamete. So these parents in meiosis are producing haploid gametes, if you take two of those haploid gametes and you fuse them together you're going to get a diploid cell, that zygote has formed from the fusion of these two haploids is now diploid. And so from that fusion we've recovered the diploid state from the adult. You start off with two diploid adults, you use meiosis to get haploid gametes, those gametes then come together and you get a diploid offspring. This process blends together genetic information. So we start off with a diploid individual #1 and a diploid individual #2, they go through meiosis and we get our haploid gametes, then those two haploid gametes which are from two different parents that have got different kinds of genes, different encoding for lets say blue eyes and brown eyes, these genes are now fusing together into an offspring, and this offspring is a blending of the two parent's genes, so we got a blue individual and a yellow individual, and the offspring is this checker board of blue and yellow individual-some of the mothers genes, some of the fathers genes. So this offspring, this zygote, is different from either one of the parents. We've got genetic information that is being mixed together, these parents together are blending together their genetic information. The big things to know about mitosis and asexual reproduction and meiosis and sexual reproduction is that in Mitosis, the goal is to leave ploidy the same and produce offspring/daughter cells that are identical to the parent cell. The goal is Meiosis is to cut the ploidy in half, to go from a diploid into a haploid, and to use that haploid gamete to blend it together with somebody else's haploid gamete and get something that is different, this combination of genes has never been seen before. Mitosis is for asexual reproduction you get identical offspring and meiosis is for sexual reproduction you get non identical offspring.

Know the three types of macronutrients, including how they move through the body and where they are stored

Macronutrients are things like Carbohydrates-sugars, starches. And Lipids- fats, oils, and Proteins. These are the macro nutrients. You can do two things with these macronutrients, you can metabolize them for energy or you can use them to build your body. Most of the physical volume of your body, the stuff that is not composed of water, is composed primarily of these products, primarily of carbohydrates, lipids, and fats. All of these 3 things can be burned, so all of these things your cells can breakdown, release the energies in these molecules, and use them to form ATP and other energy storing compounds. CARBOHYDRATES are almost entirely made of carbon, hydrogen, and oxygen molecules 1:2:1. These are present in a pretty reliable ratio. Glucose is our basic building block of sugars of carbohydrates. These are what we are best at using for energy. So sugars, particularly glucose, are what we can most easily use for ATP. If it is not immediately needed, we can store it, we can store it as glycogen, but if you got plenty of carbohydrate stores going on, if you have plenty of glycogen stores in your body, you can also transform these things into other types of biomolecules. If you have plenty plenty plenty of sugars, you can also convert these sugars into things like lipids, and to some proteins. Your body can convert that sugar into different kinds of molecules into things like lipids. *Sugars move through your body through your blood. We transport sugars dissolved in the blood in the blood plasma.* *Thats how we move sugars throughout the body from the gut where we consume it and where we are digesting it and then move it out to our tissues to give all those tissues energy*. There is hormonal control over the amount of free sugar in your blood. The pancreas and the liver work together to modulate how much sugar is present in your blood. *If you eat a lot of sugary meal and have a lot of sugar available in the blood, the pancreas says hey we have too much blood sugar, our homeostatic level is out of balance, we've got too much sugar, we need to bring that sugar level back down*. *The pancreas secretes insulin which tells the liver to go on and bind that glucose, all that blood sugar up into glycogen stores stored there in the liver*. *So carbohydrates, sugars are the primary building block, it moves around through the blood, and we get it stored in places like the liver by way of this hormonal control driving the production of glycogen*. Our next macronutrient is our LIPIDS. There is no definite ratio to carbons to hydrogens to oxygens in lipids, but lipids are composed of just hydrogens carbons and oxygens like the carbohydrates, but their ratios are different. They have lots and lots more carbons. So you can identify a lipid, one of these fatty acids, by this long tail of carbons with hydrogens binded on to each carbon. Lots of carbons. Those carbon bonds is where all of the energy in this molecule is stored. All of those carbon bonds is why fats in your diet provide more dense energy to you than a carbohydrate does. We use these things for cell membranes, we need these lipids to form phospholipids to form the cell membrane and the membranes around all of our organelles. But we can also use this for an ATP source. You can produce more ATP out of lipids than you can out of a single sugar molecule, and the reason is because we have all of these carbons linked together. Most of the lipids we consume is these long chain fatty acids these long carbon tails which have got a lot of chemical energy stored up in those bonds, a lot of energy that be converted into ATP. Sugar gets dissolved in the plasma of the blood, where it is transported and the reason it can dissolve in the plasma of the blood is because sugars are polar molecules and so they are hydrophilic they can dissolve in water and that blood plasma can move around. Lipids are hydroPHOBIC so we need a different type of transport mechanism. We cannot have globs of oil floating around in our bloodstream, we need to package those lipids up. We need to package this lipids up in something that does dissolve in water, called Lipoproteins. So we got a phospholipid layer, a single layer, a phospholipid monolayer, not a bilayer like a cell membrane. So they have their hydrophilic, their polar phosphate heads, the ones that interact with water on the outsides, and on the inside, where those phospholipid tails are those hydrophobic tails are, is a droplet of oil. All the orange stuff in the middle on the inside are the lipids that need transporting, their cholesterols which are other kinds of lipids that need moved around the body. So we package all these lipids away on the inside of this little ball, and on the outside of the ball we coat it in a hydrophilic substance, the phosphate heads of these phospholipids, and that allows this little ball of lipids, this little transport sphere to move readily through the blood plasma. Lipo refers to the lipids/fats and the protein refers to the proteins the are part of this structure. The green bits are the the protein that are part of the structure. Those proteins are involved with interacting with other parts of the body. They are receptor proteins that are helping move this sphere around through the body. Its those proteins that we are referring to when we talk about the high and low density lipoproteins of good and bad cholesterol. Low Density Lipoproteins is the bad cholesterol the bad stuff that can get clogged in your arteries. The LDL is the bad cholesterol, its low density of proteins in the cell membrane, only a quarter of the lipoprotein sphere is condensed with proteins whereas the High Density Lipoproteins, the good cholesterols, have a much higher density of proteins in the lipoprotein spheres. The LDL is a bigger sphere compared to the HDL, which causes it to get clogged in arteries. HDL is good cholesterol because its job is to go around and find places where this LDL is lost, and it takes pieces of this LDL, this stuff that is clogging your arteries, and it packages that stuff up inside itself, then wanders off elsewhere to get broken down. This stuff is cleaning up the deposits of the LDL bad cholesterol. The lipids and proteins that your body cannot produce are called essential fatty acids. Your body cannot put it together by itself, you have to get it from your diet if you're going to get it at all. You need these essential fatty acids because they are often involved in the nervous system, inflammatory response, and also in the nervous system in neural signaling. These fatty acids are involved in the communication within your brain, allowing your brain to communicate efficiently. Triglycerides are how we store lipids for long term storage. Our last macronutrient are PROTEINS and proteins differ on a molecular basis from carbs and lipids in that they contain nitrogen. The source of some of the nitrogenous waste that our kidneys get rid of is here in the digestion of proteins, that ammonia group that is hanging off the side of our protein. These guys have nitrogen, they are nitrogen based compounds, we either use these to build our own proteins, to build our own enzymes to build our own muscles, or again we can break these down and create ATP molecules out of the chemical energy stored in these molecules. All three of these macronutrients in addition to being building blocks, to being the pieces you are physically built out of, you can also burn all of them. Which means that there is energy available in them, which is energy you can break down and produce ATP from. Metabolism is our general term for rearranging the stuff that you eat into either building blocks or into energy into ATP molecules. The mitochondria is where sugars are being actively converted into ATP. You take glucose, you stick it into this complex biochemical reaction, and what you get out at the end is a whole bunch of ATP which you can then use to power all of the cellular movement, functions, pumps that your body needs. This is one tiny component of all metabolism, remember this is just carbohydrates this is just sugars being burnt, if we need to burn lipids and proteins, we need to add more to it. Recognize that the things that you eat, these macronutrients that you eat, can be burned and can enter into this metabolic cycle here to produce ATP. So fats and lipids, carbohydrates and sugars, and proteins can all be burned for energy production for ATP production. One little c calorie is what chemists use, its the measurement of energy. One big C calorie is a kilocalorie, or 1000 energetic little c calories. One little c calorie is defined as the amount of energy it takes to raise a single gram of water by one degree celsius. With our daily 2000 calorie diet, our body can produce 100-160 septillion ATP molecules.. but we don't actually do that. They do not fully convert. This is because of metabolic efficiency. We do not have perfect conversion of these macronutrients, like our body, it is an imperfect conversion. This is also because of digestion inefficiency, because its an imperfect conversion. You can eat corn, and see it in your poop later, indicating that not everything you eat gets covered into macronutrients. Some things that you eat can consume pass on through your gut. Also, because some of the consumed food is used to build structures instead of used to make energy. We can build enzymes, cell membranes, all kinds of things. We digest most of what we eat, but not all of it. Macronutrients is where we get all of our calories and energy and what builds our body. Micronutrients we find in a lot of hormonal pathways and neurotransmitter pathways. The communication in your body also goes on here with these macronutrients. Vitamins are organic and minerals are inorganic.

DIGESTIVE Know the organs of the digestive system, and understand the functions of each

Mouth to Esophagus to Stomach to Intestines to Anus. Accessory glands along the way are the pancreas, liver, and gallbladder. What the digestive system has to do is get food into it, then break down and mix around those food bits, then digest it-breaking it down from small particles into molecules, then absorb them into the body and the body's tissues, and then excrete and defecation (throwing out) anything that is left over. First organ of the digestive system is your TEETH. The teeth is mechanical digestion This is where you are first encountering a large chunk of food and first starting to break it down into smaller pieces into smaller particles. You have different kinds of teeth for different functions. You have these slicers up front here, these canines that seem to be pretty good for ripping, then you got these molars for crushing and grinding. All of that your goal is to make sort of a paste out of that carrot so to say that you are eating before you swallow it. While you're chewing, you're also salivating. Saliva lubricates the food it gets the food wet so it can easily slide down the throat, and the other is that this is where we start chemical digestion of the food. Primarily digesting carbohydrates. So there are a couple of enzymes that are secreted in the mouth that are part of the saliva, one is called salivary amylase. Amylase, that 'are' suffix means that this is an enzyme, probably an enzyme that is involved in digesting some other molecule, and the molecule that this one is digesting is amylose, a sugar based, glucose based molecule its part of starch. So the carbohydrates we find in things like bread and potatoes is large part of this amylose. So its this salivary amylAse that starts breaking that down. You also have a little bit of salivary lipase which is involved in breaking down fats thats more common in infants that are focused on breastfeeding, that are just drinking high fat milk, we lose a lot of that function of salivary lipase. So most of whats going on in the mouth is physical breakdown with the teeth, lubrication with the saliva the watery saliva, and this salivary amylase is starting the digestion of carbohydrates. Lysozyme is also good at destroying the bacteria that is in your mouth. So in through the mouth, down through the esophagus, which is a different tube than the trachea, the trachea that leads into your lungs is not where you want food to go, so its going down the esophagus, and down into the stomach. Then there is the STOMACH. The stomach is an inflatable and deflatable sack. The stomach receives food from the esophagus, this is where we really start into the business of chemical digestion and we continue the process of physical and mechanical digestion. In your stomach is where you find the lowest ph material in your body. Stomach acid is predominantly hydrochloric acid. Very low ph stuff, you're producing 2-3 liters/half a gallon of these gastric juices a day. This is working to break down the food that is in your stomach. The stomach is also very muscular so its squeezing around physically breaking food up. The other biggie in the stomach that is being produced is Pepsin. So in the mouth we have amylase to break down carbohydrates, in stomach the big secretion is pepsin, and pepsin is for breaking down proteins. So carbohydrate digestion starts in the mouth, protein digestion starts here in the stomach. Mixing and sloshing is going on in the stomach to break up and mix up all the food that is in your stomach. This ingested food, plus all these stomach secretions, is called chyme. Chyme is just the word for the stuff that is inside your gut now that we're in the stomach. It's going to be chyme until we go all the way to the end of the large intestine right before the anus. Right there at the end it turns from chyme into feces. The stomach is our organ thats regulating how much food is moving how fast through the intestines. Then the INTESTINES. Your intestines are where the majority of nutrients are absorbed by the body. So up until this point we're primarily doing some mixing and initial breakdown of the food. But now that we're in the intestine we're actually going to start absorbing food. There are three sections of the intestine. First, the Duodenum, which is 12 finger widths long, this is what receives chyme that is coming out of the stomach, and this is where some of the major digestive secretions that are not produced by the stomach itself are introduced into the chyme. Starting with our duodenum, we've got chyme that is exiting out of the stomach, remember this is very acidic low ph material, and so one of the jobs of the duodenum is to neutralize that acid. And so this is one of the highest ph the most alkaline materials thats produced in your body is produced by the pancreas and then ripped into the duodenum to neutralize that acid. Because that acid is great at digesting stuff, hydrochloric acid is going to break down proteins which is good you want it to break down proteins in your gut but you do not want it to break down the proteins OF your gut. You don't want it breaking down your body, so you need to neutralize that material before it gets out into the rest of the gut. So the pancreas is neutralizing that stuff its pumping this alkaline fluid into the duodenum to neutralize the chyme as it exits the stomach. The pancreas is located right next to the duodenum, but the liver and the gallbladder are our other biggies. Bile is a fluid thats produced as a byproduct of the breakdown of hemoglobin. So as your red blood cells expire, they break down and the release hemoglobin out into the body, and one of the things that the liver does is that it sweeps up that hemoglobin, and starts to break it down, and the byproduct of that break down is this dark green, olive-colored bile. Bile is then stored in this thing right next to the liver called the gallbladder. The gallbladder is not actively producing bile, its just storing what the liver has produced. And then that bile is released into the duodenum in response to high lipid quantities in the diet. So if you've got a lot of lipids in your diet you're eating a lot of fats in your diet, those fats are being broken down all along the way as they get down here, but because they are lipids they are not water soluble, and its the job of these bile salts to help emulsify those lipids. Bile salt allows a lipid, a hydrophobic material to dissolve in water. So these bile salts are doing that function, they're allowing these lipids to breakdown into smaller and smaller particles and dissolve into the fluid of the chyme. In summary our duodenum's function is to start the chemical process this chemical breakdown. This is where all of the digestive things are being introduced in anticipation of gastral absorption of nutrients. Then you have the Jejunum which is where most of the nutrient absorption occurs. The jejunum is a long coil of tube inside your gut here. We continue to chemically and physically break down things, those enzymes are still present. Most of these nutrients as they are being broken are being taken into the body/absorbed right here in the jejunum. Peristalsis happens from up in the throat to move food down the way happens all the way down through the stomach and down into the gut. But in the gut/intestines there is a different kind of movement. This contraction is called Segmentation. Where instead of this sort of wave of contractions, they do a rhythmic contraction, an alternating contraction in segmentation. So pinching down in this part, releasing in this part, pinching down in this part, releasing in this part, and so on. The function of segmentation is to break up and mix chyme within the gut. Peristalsis is involved in pushing food down the gut. Pinching motion is mixing it up, but not moving it in any direction. And then the Ileum and thats if there is anything left to absorb in the chyme once it reaches there then thats where it gets absorbed. Vitamin B12 is absorbed in this part of the intestines. Also, just to absorb anything else that has been missed by the jejunum. Also to recover those bile salts that were produced earlier. Those bile salts that were produced and dumped into the duodenum are now pulled back into the body here at the Ileum. Our last part of the GI tract is the COLON, this is the Large Intestine. There is no nutrient absorption going on here, but instead water reabsorption. Remember we dumped in 2-3L of gastric juices, thats mostly water, we need water to live, and so we want to reclaim that water. So its here that the water is being pulled out of the chyme, and as that chyme loses water, it becomes a drier and drier more compact material, this is where we transition from chyme into feces here at the very end in the large intestine. As the feces build up, they push down on the anus, the muscles inside of the anus. That pressure goes to your brain, and this is what you feel when you feel the urge to poop. This is where you finally regain conscious control whether you want to poop or not.

Understand how the placenta is used to exchanges gases, wastes, and nutrients between fetus and mother

One of the functions of the placenta is to bring the fetal blood and the maternal blood into close proximity. They are serperate buckets of blood, they do not mix, they do not come in direct contact, but they come in very very close proximity. We've got fetal blood thats here in the placenta that is coming through the fetuses body out through the umbilical cord out into the placenta and out there its in this close proximity to the maternal blood thats not mixing with the fetuses blood, but coming close to the fetuses blood. We've talked about hemoglobin and how hemoglobin transports oxygen. One hemoglobin molecule, if its fully saturated with oxygen, which is not something that happens all the time, but if it is fully saturated, it can carry four oxygen molecules around. And recall that binding of oxygen on to the hemoglobin can change based on the conditions that that hemoglobin is exposed to. We talked about the affects of ph on oxygens binding affinity to hemoglobin. We also talked in more detail about the effect of ambient oxygen concentration, the oxygen concentration in the tissues surrounding a pool of blood thats carrying hemoglobin and that ambient oxygen concentrations effect on hemoglobins binding of oxygen. This is how oxygen gets delivered to your tissues- in your lungs, in the alveoli of your lungs, the ambient oxygen concentration in the air that you've brought into your lungs is high. Because it is high you got high concentration of oxygen there, that drives high saturation of hemoglobin. We've got high saturation, we have a tight binding between the oxygen molecules and the hemoglobin molecules that are there in the alveoli. And as that blood moves out to your body, our goal is to deliver that oxygen out to your tissues where your cells can use it for cellular respiration. And out at your body, your body has been consuming oxygen and so the ambient concentration is low. It goes from about 100 at the alveoli down to 40ml mercury of oxygen in the body tissues. And what we see is slower saturation of hemoglobin. So that means there are fewer oxygen molecules that are bound on to the hemoglobin molecules. Where have those oxygens gone if they're no longer bound on to hemoglobin? They unbind from hemoglobin and go in to your body tissues. This is our goal; we want to get oxygen into the body tissues and so hemoglobin is no longer binding to it because hemoglobins binding affinity changes it decreases in lower ambient concentration of oxygen. And hemoglobins ability to hold oxygen drops and so those oxygen molecules fall off of the hemoglobin molecules where they can then be taken up by your cells. So this is whats happening in you everytime blood is flowing from your lungs, picking up oxygen, and then flowing out to your tissues, delivering that oxygen. But if you had a embryo or fetus inside of you, some of your oxygenated blood is going to be going not to the baby, but to the placenta or in contact with the placenta. An embryo is not breathing air, its a fluid space, so the lungs are not breathing air in and out. So until birth, the lungs are not functioning as a respiratory circus. Where the embryo is getting its oxygen is here in the placenta. This is the respiratory circus, this is where the fetus is picking up oxygen. So whats happening is you got deoxygenated blood that is coming from the body all the tissues that have consumed oxygen going down into the embryonic side of the placenta, and then at the placenta they're picking up oxygen from the maternal blood. The oxygen concentration of the mothers blood that is flowing to the placenta is high, the goal is to deliver oxygen to the baby, we're going to send oxygenated blood to the placenta. So with adult hemoglobin, we've got high concentration of oxygen and so we're going to have high saturation of those hemoglobin molecules. As that maternal blood flows towards the placenta, so its coming from the lungs, so that maternal blood has been oxygenated at the lungs, its now flowing towards the placenta. The ambient oxygen concentration at the placenta is low. It is low because the baby has been consuming oxygen, all of its cells have consumed oxygen, and then that deoxygenated blood flowed to the fetal side of the placenta. And so the ambient oxygen concentration there at the placenta is low. So we've got high concentration, high saturation oxygen moving in the maternal blood, moving into an area of low oxygen concentration. So we're moving from this area of relatively high oxygen saturation down into an area of lower oxygen saturation and as that happens, oxygen that is bound to the hemoglobin falls off. This is the same process thats delivering oxygen to your own body tissues. Your blood, high oxygen concentration high hemoglobin saturation, moves to an area of low ambient oxygen concentration. Your muscles have been working, they've consumed a lot of oxygen, and so that blood thats flowing into your muscle, is encountering an area where there is not a lot of oxygen around, and the affinity for oxygen of the hemoglobin in that blood moving into the muscle decreases. And so that hemoglobin lets go of its oxygen. That oxygen is now free to enter into your muscle cells and feed your muscles again. The proteins that make up fetal hemoglobin are slightly different and that changes the oxygen binding affinity of fetal hemoglobin, makes it a slightly different curve than the adult hemoglobin. The mothers blood is oxygenated at the high concentration lungs, and then it flows down the placenta, we talked about what the ambient oxygen concentration in the placenta is like, we talked about what happens to oxygen in maternal blood as it enters that placental region, and now i want you to think about where that oxygen goes that has been transported to the placenta in the mothers blood. So how does the developing embryo get oxygen from the mother? *So our maternal blood picks up oxygen at the lungs, high concentration of ambient oxygen and so high saturation of maternal hemoglobin. Now our maternal oxygen flows to the maternal side of the placenta which is an area of relatively low oxygen concentration because our baby has been consuming all of this oxygen. At this point, we've got this drop from full saturation to something less than full saturation, and what that means is that some of those oxygen molecules fall off of the hemoglobin, and they are floating free, and now they're available to be taken up by something. And the something they're going to be taken up by is FETAL HEMOGLOBIN. So at this same ambient oxygen concentration, the binding affinity of fetal hemoglobin is high-higher than that of the maternal hemoglobin. And so any of this oxygen that falls off of the maternal hemoglobin because the ambient oxygen concentration has fallen off here, is going to get taken up by this fetal hemoglobin. So this is how oxygen gets transmitted from the mother into the baby, its by way of this DIFFERENT BINDING AFFINITY OF HEMOGLOBIN TO OXYGEN IN THE DIFFERENT POOLS OF BLOOD.

THANKSGIVING Understand why turkey and mashed potatoes are both necessary to induce a post-dinner nap

Protein is a major component of turkey, as well as water, but take away the water and what you are left with is a large amount of protein. Protein is made up of amino acids, we have 20 different amino acid types. Some of them are essential amino acids meaning that they are amino acids that we can not synthesize, that our body cannot construct, so we have to get these from our diet. Turkeys are a good source to find the essential amino acids. Turkey supplies all of the essential amino acids. The essential amino acid TRYPTOPHAN is the explanation given for why we fall asleep after dinner. If you eat all this turkey its landed with tryptophan and then it makes you sleepy and thats why everybody takes a nap after thanksgiving dinner. So you consume tryptophan, you consume it in your diet, for example from a turkey, and its converted into Serotonin, which is an important neurotransmitter. And serotonin can separately be converted into melatonin, another important neurochemical. So we eat tryptophan, it gets converted into first serotonin and some of that serotonin can be used to make melatonin. Serotonin is a central nervous system neurotransmitter, it is involved in mood regulation, its particularly important in maintaining a good mood. Antidepressant drugs target serotonin, it leaves serotonin out in the brain space, triggering neurons that'll improve your mood make your mood more stable and not allow that serotonin to be taken up back into the cells where its not going to function. So serotonin is a product of tryptophan, one of the amino acids that we find in turkey. The other thing that is important is melatonin. We take our serotonin our good mood hormone our good mood neurotransmitter and it can be converted into melatonin. Melatonin is used by your body to regulate daily cycles. So this circadian rhythm is the cycling your body goes through on a daily basis where you're alert in the morning and you get a little more sedate, and in the afternoon you pick back up and your alertness picks back up and right before bedtime your body starts relaxing shutting down in preparation for sleep. Its melatonin that is released by your body just prior to bedtime that starts calming your body down relaxing your body. And this idea of thanksgiving dinner full of turkey full of tryptophan making you sleep the idea works like this: you consume a lot of tryptophan, it gets converted into serotonin which puts you in a good mood makes you happy calm relaxed, and that serotonin can be used to produce melatonin which then starts putting you to sleep. By filling up the stomach, the stomach is involved in the endocrine system, one of the hormones that the endocrine system produces stimulates the parasympathetic nervous system. So when the stomach fills, it sends messages to the brain, so the parasympathetic nervous system, saying hey i got a lot of food here, we need to calm the body down so i can digest this. The parasympathetic system serves to calm you down, to dedicate your body's energy to digestion, and when your stomach is full it stimulates the parasympathetic nervous system to do this rest and digest function, so your body overall stress level is declined. In the stomach these complex carbs that you eat in a mound of mashed potatoes get broken down into simpler and simpler sugars. So here in the stomach high carbohydrate food in your meal breaks apart into glucose, that glucose then goes out into your blood stream, and increases your blood sugar levels. So if you eat high carbohydrate foods, if you eat a lot of mashed potatoes along with your turkey, that increases your blood glucose level. So this high blood sugar thats in the blood is detected by the pancreas and the pancreas in response produces insulin. And the idea of insulin is to take all this excess sugar thats in the blood, package it up as glycogen, and store it away in the liver. Thats one function of insulin but another one is that insulin goes to the skeletal muscles. So insulin in the skeletal muscles induces the skeletal muscles to start taking up specific proteins from the blood. So you've eaten this meal thats high in sugar, the food that you're eating not only has carbohydrates but also probably has proteins in it, and so you have all this food floating around in the blood, all these nutrients floating around, the skeletal muscles, the ones that operate your gross motor activity, are wanting to take that protein so they can grow. And insulin is one of the hormones that stimulates skeletal muscles to take in these proteins, but importantly they only take up specific kinds of amino acids, there is three main ones that they target, doesn't matter which ones they are but the important thing is that they do not take up tryptophan, so they're taking up a lot of the amino acids, but not tryptophan. And so what that does is it leaves a lot of tryptophan in your blood stream. So this meal that you're eating your mashed potatoes and your turkey, you've got the mashed potatoes breaking down into glucose, increasing your insulin, which causes your muscles to take up amino acids, but leaves behind the tryptophan, this amino acid that you got from the turkey. That tryptophan can then travel through the bloodstream to the brain. And at the brain, this is the important note, at the brain, tryptophan is now a higher relative concentration than other amino acids, other amino acids have been taken in by the skeletal muscles, and the tryptophan is left behind. And so that leaves tryptophan as this material that is the highest relative abundance, or atleast a higher general relative abundance than other amino acids at this blood brain barrier. And so when amino acids are being taken into the brain, even if the brain is just taking in what happens to be there, because these other amino acids have been taken in by the muscles, tryptophan is whats left over to cross into the brain. And then its in the brain the tryptophan can convert into serotonin and into melatonin. And then we talked about how serotonin and melatonin can make you sleepy. So can turkey make you sleepy? The answer is yes, turkey has tryptophan, tryptophan can get into the brain, it can convert into serotonin and melatonin which do make you sleepy, but it doesn't happen by itself. It has to happen alongside this other part, this carbohydrate breakdown into blood sugar, which releases insulin which causes your muscles to take in other amino acids, leaving the tryptophan available for the brain. So yes. 0.24 grams of tryptophan in turkey for every 100 grams of food is a relatively high amount. Its not just tryptophan operating by itself that causes this sleepiness, its tryptophan alongside of a high carbohydrate rich meal. So yeah turkey has tryptophan, yeah tryptophan makes you sleepy, lots of other things have tryptophan and don't make you sleepy because we generally don't eat them in large quantities like we tend to do with turkey at thanksgiving meals. So more important than simply the tryptophan content in a meal, its what else is going on in the meal. If you eat a large amount of food, thats a lot of carbohydrates, high blood sugar, high insulin, and so a high relative concentration of tryptophan left in the blood to go into the brain to enter this melatonin production. In conclusion, food comas are real, but don't blame just the turkey. The turkey is a part of this story, but its not the only culprit making you tired after your thanksgiving meal. Low Serotonin makes you hangry. Serotonin is this hormone that calms you down, makes your mood stable, makes you in a good mood. So if you have low serotonin, you get in a cranky mood because of a lack of serotonin. You're going to have high levels of tryptophan and melatonin after you've eaten. So high tryptophan after you've eaten a lot of tryptophan in your diet, high melatonin after a lot of that tryptophan thats in your blood gets into the brain, converts serotonin, and then into melatonin. SO if you're not eating, you have this low serotonin, and you get grumpy. Your body also interprets low blood sugar as an emergency, and so if you haven't been eating, your blood sugar level is dropping, your body says something is wrong lets stimulate the stress response, lets stimulate the fight or flight, so it stimulates sympathetic nervous system, releases adrenaline into your body, and releases cortisol, which is the long term stress hormone. All of those things are amping you up, your serotonin is low, and you get really grouchy if you don't have food. Eating tryptophan and carbohydrates makes you wanna nap. Turkey does contain tryptophan but no more so than chicken, beef, and other meats. The drowsiness you feel after a rich Thanksgiving meal might result from the inclusion of large amounts of carbohydrates (the dressing, rolls, Mashed Potatoes), which increases the production of sleep-inducing melatonin in the brain.

Understand what is meant by homozygous, heterozygous, dominant, and recessive

So our parent generation of all purple flowers all interbreed with eachother, and you get all purple pure breeding generation. He also had the pure breeding white flower peas and all of these white flower peas whenever he bred them with eachother they only produced white flower individuals. You can keep going down generations with this and you always get the same color flowers. This family tree here is always producing all purple flowers and the other producing all white flowers. He then started crossing. If you start with the parents being one purple flower and one white flower, that the F1 generation (the first offspring of the parents) are all purple flowers. The hypothesis at that time in the 1800s was that the inheritance of genes and physical features was a blended average of both the mom and dads genes and features. Mendel observed that that was not was going on in the peas. Mendel then observed what would happen if he were to cross these offspring with eachother. So this F1 generation we cross them with eachother we get an F2, now two generations. Before, we would blend purple flower and a white flower and we got all purple flowers. Now he took the F1 generation that was a blend of the purple and white flowers resulting in all white flowers, he took those and crossed them, and what he got was mostly purple flowers in the F2 generation, and a few white flower individuals. 3 purple flowers, and 1 white flower. Ratio of 75% purple to 25% white flower individuals. So to summarize that we started with two pure breeding lines. A pure breeding purple line and a pure breeding white line. When you cross those two, the F1 generation that you get all produces purple flowers. So all of the offspring of the F1 generation all look like just the purple parent and not the white parent. But if you cross two of those F1 individuals, then the F2 generation, their offspring recovers some of the original white parent flowers appearance. So we get some of that original white flower line back, but mostly purple flower individuals (3 to 1 ratio). Then he started wondering what could cause this pattern, so he came up with a series of hypothesis. The first one was that these 'heritable units', so purpleness and whiteness are heritable units that the pea plants can inherit purpleness or whiteness from its parents. He said that these heritable units exist in pairs in the parents. He said that each of the parents, our pure breeding purple parent our pure breeding white parent, they have two copies a pair of each heritable unit. So purple pure breeding line would have to copies of the purple heritable unit and white would have two of the white. That was his first hypothesis. His second hypothesis was that one of these heritable units was what he called DOMINANT to the other. Which means that every individual that has both a purple and a white heritable unit, only the purple one will matter. So the white heritable unit is present, but its possible appearance in the offspring gets overwhelmed by the purple heritable unit. So in the presence of both these different kinds, if you got one purple and one white inheritable unit, then your appearance is just purple you look identical to an individual that has two of the purple heritable units. His final hypothesis was when gametes are formed, so when the pollen is formed when the eggs are formed for these flowers, only one of the two heritable units that a parent has gets put into a given gamete. And so if you're a pure breeding purple parent, that means you have two purple heritable units, and when you produce gametes, you have one of those purple units goes into one gamete and the other one goes into the other gamete. And so all of your gametes has a single purple heritable unit in them. If you're a white pure breeding parent then the same applies, you got gametes that each have just one white heritable unit in them and if you have one of each these heritable units, one purple and one white one, then when you make gametes half of them will have the purple heritable unit and half of them will have the white heritable unit. So these three hypothesis is what Mendell came up with to explain the patterns that he was seeing when he crossed two pure breeding lines and then crossed that F1 generation to find this F2 generation. If an individual has two of the same heritable units, so our pure breeding purple line has two purple units, our pure breeding white line has two white units, in either case we call that a homozygote, or we call that the HOMOZYGOTE condition. Homo means the same, so this has two of the same heritable units. If you got one of each kind, one purple heritable unit and one white heritable unit, then you have different heritable units and so we call that a heterozygote, HETEROZYGOUS. So we have homozygotes, either in the dominant form, the purple form, or homozygotes with the recessive the non-dominant form. And then we also have heterozygotes which have one of each the dominant and the non dominant form.

Know what is meant by the term "fitness"

So this combination of Survival and Reproduction, of differential survival, so some individuals can survive better than others and some that reproduce better than others, together we call FITNESS. So Natural Selection also known as survival of the fittest, states that fitter individuals are selected for. That fitter individuals if they reproduce more frequently if they survive better, then those individuals alleles increase in relative frequency in the population. And that increase in relative frequency of alleles is what we call Fitness, this combo of good survival and good reproduction.

Understand why a diet high in plant material tends to be healthier both in terms of macro- and micro-nutrients

The general recommendation for what you should eat is not too much, eat some but not too much, don't over-do it with the macronutrients in particular. Eat a high diversity of things, so eat a lot of different kinds of foods, all of those different kinds of foods are going to be containing different kinds of micronutrients, and different amounts of those micronutrients. So if you're eating a high diversity of things, you're going to be sampling a little bit of your cobalt over here, a little bit of your vitamin D over here, and some of your vitamin B's over here, and averaging all of that together you get a complete compliment of all of these nutrients you need. The last recommendation is to include a lot of plant matter in your diet. Plants tend to be high in these micronutrients. This is typically where we find micronutrients in the highest density is in plant matter. They are also less dense with the macronutrients, this is a nice way to avoid consuming alot of high calorie dense foods by eating a lot of plants.

Recognize that all life forms, including humans, experience natural selection and can evolve

The idea of allele change through time, evolution was not new. Darwin was not coming up with the idea of evolution, he was coming up with the mechanism for evolution. The idea of natural selection, the differential reproductive success, differential survival, lead to a change in allele frequency which is evolution. Lamarckian evolution is giraffes that had to stretch their neck to reach leaves that were the only food available. And by stretching their necks, their necks got a little bit longer through time in their own lifetime so their offspring had longer necks. And as we go through time, we ended up with a very long necked giraffe. But now we've discovered we do not change our DNA we do not change our alleles based on how stretchy we try to make ourselves, you may get taller, but your offspring will not, you will not be able to pass on that acquired trait. Evolution is Only working on whatevers present in a population whatever alleles are already present is the only thing evolution can really work on. Natural Selection does not look at an open available resource like food, all natural selection is doing is seeing that we have some variation in this environment some variation in all of your phenotypes and some of you are better at survival than others because of the environment in which you live, and those of you that are better at surviving are gonna be the ones that survive and reproduce and pass down alleles to future generations. We are multicellular organisms, but not all organisms are, the most adaptive organism on this planet are bacteria single celled organisms, no nuclei. So evolution doesn't do well with complexity. Evolution by natural selection IS when an allele thats present in a population, confers better survival or better reproductive success to that individual so if it gives you a more fit phenotype then that allele will become more abundant in the population. The things we need for evolution to occur are genotypic variation. If we don't have variation, we cannot change allele frequencies. So if all the alleles are exactly identical, and theres no opportunity to mutate and create new ones, then evolution cannot occur. The next step is that that genotypic variation has to lead into some type of phenotypic variation. Even if we have different alleles, if we all look identical, remember that our environment interacts with us all in the same way, and so phenotypic variation is important for evolution. And then these different phenotypes lead to either better survival or reproductive success causing natural fitness to work on the population.

Know which enzymes are used to digest different macronutrients, and know where they are formed

The pancreas is producing lots and lots of digestive enzymes. We've got Carbohydrate digestive enzymes-so Sucrase (digests sucrose), Lactase, Maltase, and Amylase. We've also got protein digestive enzymes being produced in the Pancreas. Also, there is lipid digestive enzymes, specially Lipase that is being produced by the Pancreas. The digestive enzyme lipase digests triglycerides because triglycerides are the storage molecule for lipids, so triglycerides are a type of lipid. We start carbohydrate digestion in the mouth, we start protein digestion in the stomach, and we start this lipid digestion, the majority of adult lipid digestion starts in the duodenum just downstream from the stomach.

Know what peristalsis is, and understand how it moves food through the GI tract

This is the last time that you have conscious control at when you swallow. This is the last point in which you have conscious control of whats going on in your digestive system. From here on down is all unconscious control. You got smooth muscles involved in squishing this food down through the digestive system. This squishing motion is called PERISTALSIS which is a wave of muscle contraction that moves down the tube. You've got these muscles that are wrapped around digestive tract around the GI (gastro intestinal) tract that are squeezing in this wave to move food in one direction own through the gut.

Understand the difference between genotype and phenotype

We can describe an individual, one of you one of the pea plants a cat, in either talking about the way that its genes look what kinds of alleles are present or we can describe it in terms of what is physically appears to be like or what it behaves like or how it functions. If we're describing the gene if we're describing the allele which specific alleles are present in an individual, we call it the GENOTYPE, so the type of genes that are present. For example we might have a pea plant that has one purple flower allele and one white flower allele, that description is the GENOTYPE, what specially are the alleles that are present. In our notation from the friday that was the big P for purple flowered allele and the little p for the white flowered allele, so this big P little p notation is the description of the genotype, what specific kinds of alleles are present in this individual. If we describe it as its appearance, what it looks like, we're not invested in what its genes are but just what it appears to be, thats our PHENOTYPE. The PHENOTYPE is the description of your appearance the behavior and function of your organism. And in this case, the flowers are purple is our Phenotypic description of this individual. So genotype of big P little p and phenotype of this flower is purple are two different kinds of descriptions of the individual. In our purple and white flowers we talked about Homozygotes, ones that got two copies of the same allele and different copies Heterozygotes. So up at the top we got two big Ps thats our genotype and our phenotype is a purple flower because it has two copies of the purple allele. Our other homozygote the two little ps down here has two copies of the white flower allele and so its phenotype is white flowers. The heterozygote though, the one that has a big P and a little p, because the purple flowered allele is DOMINANT to the white flower allele, in the presence of a purple flower allele that purple coloration will come through and the white coloration will not be apparent. And so in this case we got a heterozygote the big P little p, the genotype which is different from our homozygote big P big P but has the same phenotype. So both of those different genotypes result in the same phenotype the same appearance. P allele (purple) is dominant, p allele (white) is recessive. A HOMOZYGOTE regardless if its dominant or recessive, as long as its a homozygote is a pure breeding line. Incomplete Dominance is where there is sort of a dominant allele and this curly hair allele is sort of dominant to the straight haired allele, however its not fully dominant. And so the presence of this big H (the curly haired allele) if there is two of those alleles present then you got curly hair. If you only have one H present and the other allele is the recessive little h allele the straight haired allele, you don't get curly hair but you get sort of curly hair, you get sort of a halfway between straight and curly. And if you're a homozygote straight hair allele little h allele then you got straight hair. But this sort of blended phenotype or heterozygote is called Incomplete Dominance, where our pseudo dominant allele is not fully dominant doesn't fully overwhelm the other allele type. Another type of exception of dominance is called Co-Dominance. Blood type is either A or B or AB or O. Those letters are referring to the kinds of surface proteins that are on your red blood cells. So think back to our immune system talk we were talking about antigens the surface proteins that are on lets say bacteria that your body recognizes as something thats foreign to my body. These A and B surface proteins are the same sorts of things but they're being used by your body tor recognize your red blood cells as part of you, so its how your immune system recognizes that your red blood cells are infact a part of your body and to not be destroyed. If you have the A type allele, you will express the A type surface protein. If you have the B type allele you'll express the B type surface protein. And thats if you have either if you're a homozygote so you have an A and an A allele, or a B and a B allele, OR if you have the A allele and a broken version of the allele, thats the O the O is not working the protein its a non functional one. So if you're an AA or an AO, then you have an A type blood you're producing these A type surface proteins. But if you're an AB blood type that means you have an A allele and a B allele and you'll produce both A surface proteins and B surface proteins. And so this Co-Dominance says that you've got these two different alleles and each one of them is functioning independently. If you only have one of the allele types either A or B, your phenotype only appears as A blood or B blood. But if you have AB allele your genotype is AB, then your phenotype is both of those you express both A and B, rather than A overwhelming B for example. There are 5 or 6 genes that are controlling skin tone, this is called a Polygenic Trait. So this a phenotypic trait, your skin color is an appearance, and this specific phenotype you have is controlled by many genes. Skin color is tricky because its not only controlled by your genotype but by your environment. Going out in the sun with pale skin and getting a tan is a change in your phenotype but not your genotype. Height is another example of a phenotype that can be altered by the environment. If you have tall genes, and you don't eat well, you're malnourished and don't grow properly. Another example of how environmental factors engage with genes.

NUTRITION Know the difference between macro- and micro- nutrients

We categorize nutrients- the things we eat to survive, in two broad categories: MACRONUTRIENTS are basic biochemical pieces: lipids, carbohydrates, amino acids and proteins. All of those are considered macronutrients. These are the things you need a lot of. Macro means large. These are the things that provide the bulk of your diet. Most of the food that you consume is composed of these macronutrients. Then there are things that you need in a very small quantity, you need them to live, but you don't need very much of them. We call them MICRONUTRIENTS. We divide them into two categories: One is vitamins which are organic molecules the you need small amounts of and Minerals which are inorganic molecules, things like ions, salts, etc. that you need very small amounts of. So these vitamins and minerals are these micronutrients.

ECOLOGY Understand the concept of carrying capacity as it pertains to human population

We have 7.5 billion people on the planet as of today. If we keep exponentially growing, we will overflow. If we have more humans than the rest of the planet, so physically more humans than the planet can occupy. More mass of humans than the mass of the planet. So thats obviously unrealistic, an exponential growth curve cannot realistically continue indefinitely. If we call the entire world our environment, theres some limit to how many humans can be on the planet, but we're not there yet we are still able to grow exponentially so we have not hit that ceiling yet, but the expectation is that we will at some point. The risk as we come closer to that growth limit, is a condition where we have too many individuals living in this environment, and all that crowding of individuals means that everyone of those individuals suffers. Not one of these goldfish that are crammed in the fishbowl is particularly happy in that environment even if perhaps all of those goldfish are alive. So this concept of exponential growth curve flattening out at some ceiling at some upper threshold is called CARRYING CAPACITY. This is the capacity of the environment to carry the individuals of that species, how many total individuals can our environment support. By which I mean how many can we physically fit, cram into that space. How much for is available how much water is available for those individuals. In theory, any species should increase exponentially for a time and then and we get closer and closer to that carrying capacity, to that ultimate limit of how many individuals can be supported, our population size out to start leveling off, at up here at this carrying capacity we'll probably wiggle around bouncing above and below that carrying capacity but staying about at that constant level. Carrying Capacity is set by limiting resources. So space, water, food, access to mates, protection from predators these are also important things for all kinds of species. But there is some limit to how much your environment can provide for all of these different resources, and eventually some of these resources will become limiting, and its these limits that set the upper bound population sense. The current estimates for what the earth can reasonably support the number of individuals that the world can reasonably support for humans is about 10 billion. So we're at 7.5 billion right now, we got there in basically the last two centuries. We're heading over 8 billion within the next decade or so, and then we have 2 billion more before we reach the absolute limit of 10 billion that the earth cannot support additional humans. If we continue with these patterns its very likely that in your lifetime we will reach this carrying capacity of 10 billion and maybe extend that beyond that. There are problems of food acres of water access of space access for humans that will be challenges that you will face in your lifetime. One of the biggies is food access. In general, human history has been that of the hunter-gatherer of the individuals wandering around looking for food where it exists. And thats fine if you're in a small population if you have a small group of individuals, you can follow a food source around, that works okay, but its dependent on the boom and bust environment, the environment is occasionally producing a lot of food and occasionally not, and so u have to go wandering around a lot to get that food resource. As human society developed and human population started to increase, we needed a way to supply food on a more reliable basis, this boom and bust way is not good for a large population. This development of agriculture allowed humans to have both a larger food resource, as well as a more reliable one. And through agriculture, we've been able to increase our populations above what a wild gatherer might be able to support. More recently we feed our world with agriculture. We grow food, we go out and harvest food, almost everything that you eat was intentionally grown was intentionally farmed. Almost all of the plant and animal material that we eat is farmed. The few exceptions are fish and mushrooms and a few foraged foods. Everything else we consume is farmed, plants and animals, this is the way we feed the world, through agriculture. Growing high density edible crops in localized areas.

Know the process of childbirth

We haven't gotten our baby out yet and we need to get it out. We're squeezing on the uterus, the oxytocin is causing these contractions and now we gotta deliver this thing. Three steps to delivery, we got to prepare for it, we gotta get the baby out and then we gotta get all the other stuff out that was supporting the baby in particular the placenta has to come out. And so for our preparatory stage this is DILATION. This is the opening up of the cervix to allow the babies head and then the body slides out afterwards to get that baby out. So Dilation is where the cervix goes from this very thick and circular muscle into a very thin and wide opening here that allows the babies head to come out. If the amniotic sac you're going to break the water is breaking like you see in the movies, thats going to happen now as all these contractions are squeezing on the amniotic sac and might burst it like a water balloon this is when thats going to occur. Our next step of delivery is EXPULSION. So now that the cervix is open wide, the babys head can fit out can slide out of the pelvic opening and once that head gets out the head is the hard part of childbirth. Once the head is out then you get one shoulder that comes out followed by its arm and then the other shoulders arm goes out relatively easy and then everything else is narrower than the head and the shoulders, the rest just comes out very rapidly. So all the pain and creaming is from particular the head. And then finally the last part after the baby is being born, is called the AFTERBIRTH. The uterus continues contracting, oxytocin production continues, we've got to get this placenta out. Remember the placenta was embedded in the endometrium the lining of the uterus, that has to tear free and be excelled from the mothers body. And so we got this baby thats attached to this umbilical cord and the umbilical cord is now pulling the placenta off of the uterine lining so it can also be expelled. Getting the placenta out is a very important part of birth, if it doesn't come out, it can sit inside the uterus and rot and cause sever infection. So this really important to get all of the baby, get it out of the body, including the placenta and the umbilical cord.

PREGNANCY Know the progression of early development (from gametes to zygote to morula to blastocyst to gastrula to embryo to fetus to infant), and know generally the characteristics of each

We start with GAMETES. Human gametes are sperm and eggs, you bring those two gametes together you fuse them into one cell you get a ZYGOTE, that zygote is now a single cell that results from two fused gametes, and as that zygote starts to divide, we get an EMBRYO as we start developing more and more organs and not just a blob of cells, we get into the embryo we get into the FETUS when it vaguely starts looking like the mature form baby like a human, and when that fetus exits the body exits the female reproductive tract we call it an INFANT. You can tell who is female in a sexually reproducing species by the size of the gametes, the female makes larger gametes than the male. So we got our GAMETES, we now need to fuse them together. We're going to fuse them together and form a ZYGOTE and so this is called your Zygotic stage of development. This is the first two weeks of human development. Within this two weeks, there is actually some period prior to the sperm and egg fusing together. So its not a zygote the entire period of these two weeks, but we call the whole stage the zygotic stage. Ovulation is the release of the ovary from the oocyte of the egg, that egg then travels down the fallopian tube where it encounters a sperm cell, the sperm and the egg fuse together, that leads to fertilization, and finally that zygote, that fused cell, implants in the wall of the uterus. So this is the whole stage of the zygote for a human. So the first bits of that are preparation, so we have to prepare both the sperm and the eggs. Here we got an ovary releasing an egg out into the fallopian tube, and over here we got sperm cells, sperm are produced in the testes and go through a series of vessels a series of tubes and along that way they are maturing. They are released by the male body in a still slightly immature stage. So here is our sperm cell that is being ejaculated from the male, it is coated in cholesterol. Its got this cholesterol sheath around the sperm cell, and that cholesterol sheath is sort of a protective layer, to both protect the sperm from its environment, but also to protect the environment from the sperm itself. The sperm has this little blue head on the front of the round head of the sperm, its called the acrosome, and its a digestive enzyme, its gonna use that acrosome to boar into the egg in just a moment, and we wanna protect the male body from this digestive function of these sperm cells, so the cholesterol coat is part of this function. These sperm get into the female reproductive tract, the cholesterol coat peels back because of the mucous linings in the female, and these sperm are now capacitated, they are now capable of doing their functions, swimming up through the uterus, through the fallopian tube to seek out and penetrate into an egg cell. So up in the fallopian tube we got an oocyte an egg cell, and seem that have met up with it, have swum up through the vagina, through the uterus, through the fallopian tube, and have now found an egg cell. This swimming of sperm up into the fallopian tube can take a half n hour up to two hours for them to move up there. There are thought to be some uterine contractions to help pull sperm up farther and farther up into the uterus and up towards the fallopian tubes. Theres gotta be something else because the sperm can't swim that distance that fast in that short amount of time. But if they find an egg cell thats great they'll try to boar into it they'll try to fertilize that egg cell. If they don't find an egg cell, those sperm can live in the fallopian tube for a period of several days. So 3-5 days. Those sperm cells remain competent remain living in the fallopian tube seeking out an egg cell. And if no egg cell happens by in those 3-5 days, then those sperm cells will all die and you don't get fertilization, but if they're hanging out for 3-5 days and a new oocyte is released, then they are still competent to fertilize it. So you've got your egg, you've got a sperm cell that has found it, it now needs to get into the egg. And the egg is trying not to be penetrated by lots and lots of sperm, it only wants a single sperm cell to get into the egg cell, because if you get too much sperm in there you're going to get lots and lots of DNA, way too many chromosomes, and the zygote is not going to be functional. You want just one sperm to get in, and so there is automatically this thing that blocks sperm penetration. We've got our oocyte here in the middle, and its surrounded by all these supporting cells, and those supporting cells are doing two things. One they are physically getting in the way of sperm trying to gain access to the egg. And two they are secreting proteins and enzymes that are also creating a physical and chemical barrier to sperm getting in. And this is where the sperms acrosome, that little blue hat that the sperm cell was wearing earlier comes into play. Those acrosome proteins, those digestive enzymes, are released and start boaring their way through these protective cells through the protective coat to try and get into the egg cell. When one sperm cell gets into the egg, it has this clear gelatinous shell around it that swells with water, and pulls all the other sperm that are trying to access the egg away from the egg cell. This swelling of this outer layer is how sea urchins prevent multiple sperm from penetrating into the egg. This is a condition called Polyspermy- too many sperm. Humans DONT do this, we don't have this coat that swells and expands, we do have a coat on our egg cells, and that coat hardens. Instead of swelling out like the chin does in a watery environment, it hardens to block access to multiple sperm. So we've got a blockage from polyspermy to prevent multiple sperm access to the egg. Now we got the sperm cell boared into the egg cell, and once its in there, it needs to release its nucleus, the little package that contains DNA, and allow that nucleus to migrate, to meet up with the eggs nucleus. When those two nuclei meet up, they fuse, and you now get these two haploid cells, the two haploid gametes, now dump all of their chromosomes into one nucleus, and you're left with a diploid zygote. This cell here, this fusion of first of the penetration of the sperm into the egg cell and then the fusion of the two nuclei is what leads to fertilization. This is how we create a diploid cell, recover the diploid state from these two haploid gametes. Once you have that zygote, this cell can now begin dividing. This is the one cell into the two cell stage, four cells, eight cells, that'll continue to divide, we'll continue to see these even divisions into the 16, the 32 cell stage, up to about 100 cells or so. At about 100 cells different unusual things start happening to the different cells. But this is how all of us began. We began with the fusion of one sperm and one egg cell, those two nuclei fusing together to cause fertilization, and then that zygote that resulted from those two fused gametes starts this division into a multicellular organism. All of that business happens very very quickly. So we're talking the first couple of days of post ovulation. So this is the egg is ovulated to release from the ovary, sperm meet up with it, at about a day or so within about a day of release, and then in about two days, this little ball of developing cells, growing cells, is migrated down the fallopian tube, and into the uterus. And after about three days it enters as this solid 16 cell ball called the MORULA. That name means a solid ball of cells. So weve got a whole bunch of cells all packed tight together inside the egg envelope. And from there it just hangs out in the uterus for a little bit. For the first week post ovulation all we were is just a little ball of cells floating down the fallopian tube and floating in the uterus. At our morula stage is where we can get identical twins. So identical twins are genetically identical. They result from a single egg penetrated and fertilized by a single sperm cell. And its at this morula stage, so this is our early division, a ball of cells maybe 16 maybe 32 cells. At this stage, if something happens to disturb this embryo, disturb this developing morula, and it breaks that morula into two, so you got a 16 cell ball of cells and it breaks into two separate 8 cell balls, those two separate eight cell balls they're genetically identical, and they can survive. And they will divide again, they'll divide again to 16 cell balls, and and they'll keep on growing as if they didn't split in the first place. And so identical twins come from something that happens to break this morula in half. Fraternal twins are non genetically identical. They result from two separate oocytes being released simultaneously. And then each of those oocytes penetrated by a different sperm fertilized by different sperm developing into embryos and infants that are related to eachother but are not identical. So two separate eggs get fertilized you get fraternal twins. If you get one egg one fertilized egg that breaks in half, and each of those halves develops, you get identical twins. So we got our Morula, our solid ball of cells, if you remember when we talked about cancers, early cancers also start off as solid balls of cells. But what happens is as that cancer grows, the cells that are at the inside of that ball are not able to get the nutrients that they need from diffusion, they're too far away from sources of nutrients. And so in the case of cancers, what cancers do is they recruit blood vessels in to penetrate into that developing mass of cells to feed it nutrients. But in the case of a developing embryo, the other alternative is to move from a solid ball of cells into a hollow ball of cells, and thats what happens here. We move from our Morula, which is the solid ball of cells, into the BLASTOCYST which is a hollow ball. So we've now got this sort of perimeter of cells and a fluid space on the inside. And there is one little part of this cell that doesn't get entirely shoved to the perimeter of this ball. Theres this little mass of cells that is retained in the interior of this ball of cells. And it is that little mass of cells that became you. It's this little mass, not the whole sphere, that little blob that develops into the embryo. This is what will become the developing fetus. And all the rest, this perimeter here, the outer wall, most of it will become part of the placenta to feed this developing fetus. So we've got our little blastocyst floating down, hanging out in the uterus, and its next job is implantation. So it needs to embed itself in the wall of the uterus, and its embedded in the wall of the uterus where its going to get all of its nutrition for the coming 9 months. So we've got at about 6 days, this is one week past ovulation, we've this this little blastocyst and its trying to get into the endometrium, the lining of the uterus, and it starts getting enveloped, it sinks down into the endometrium, is wrapped around by endometrial cells and at the end of 14 days, so two weeks post ovulation, we've got this blastocyst that is fully enveloped into he wall of the uterus fully enveloped by the endometrium. Its at this stage at 14 days if this implantation does not happen, this is when regular menstruation would occur. But if this does happen, then that endometrium, the lining of the uterus that gets shed during menstruation, if you got a blastocyst thats embedded into the endometrium, you want to retain it you want to feed it you want to let it develop so you can reproduce so you can have your offspring, and so this endometrium is not shed at 14 days. And its typically here that a woman would first realize that she's pregnant, that she's not having her regular period which is first cue that you have implantation of a blastocyst. So two weeks post ovulation we've got the egg is penetrated by the sperm cell, it divides into a morula, that morula that solid ball expands out into a hollow ball, a blastocyst, and that blastocyst sticks down into the endometrium. And once its in the endometrium it can now start harvesting nutrients from the mothers body. So this is the END of our zygote stage. Our next step is into the EMBRYONIC STAGE. And in the embryonic stage, we're looking at the development of organs, the differentiation of tissues, and and aiming our way towards looking like a human. So we're gonna start out here at our blastocyst, we've got our hollow ball on the outside, and theres this little ball of cells tucked away in the interior of the blastocyst that becomes you that becomes the developing embryo. You have this little embryo here, its growing larger and larger, its this little pink thing here in between the blue and yellow developing portions of this blob, again this little pink thing is the developing embryo, its surrounded by this blue amniotic cavity this is the fluid filled sac that the embryo develops inside of. And this yellow bit here, this yellow bit is the yolk sack, we don't think of humans as having yolks, but humans have yolks as well, we lose our yolks well before we are observed from the outside world, but you intact have a yolk sac just like a bird way back when you were a 25 day old embryo. And we end the Embryonic stage when we start seeing a gut. When the gut first appears, thats when our differentiation of cells is really starting to accelerate into the differentiation of organs. So up until this stage here a couple of weeks, there is this mass of cells in the middle surrounded by the amniotic sac with that yolk sac, but not a lot of really obvious structures yet, but by the end of about a month post ovulation this is when we start seeing recognizable organs. We start seeing the gut. And because we start seeing a gut and start seeing these recognizable bits, we have a new name for this structure. And instead of a Blastocyst, this is now a GASTRULA. Gastric refers to the stomach the digestion. So this gastrula is where we first see the formation of the gut. We've also see all these cells that have been dividing start to differentiate into different layers of tissues. So we start seeing a top layer a middle layer and an inner layer. These are called Germ Layers. And moving from the outside in, we've got the Ectoderm. The ectoderm develops into your exterior features. So your epidermis, your outer layer of skin, derives from the ectoderm, its the outer layer of this developing embryo. It also forms the lining of your mouth, the lining of your anus, and it forms your nervous system. This same tissue forms your skin, your anus, your mouth, and your brain. The next layer down is the Mesoderm, this forms most of the internal organs. You've got your skeleton, your muscles, the kidney the blood are all formed from the mesoderm. And then finally the Endoderm, which is the border of this yellow yolk sac. The endoderm forms the digestive system, the gut, so this is what gives our gastrula its name and also forms a couple other structures. The alveoli in your lungs, your liver, most of your endocrine glands, are endodermal tissues. So in this embryonic stage, what we;re looking at is the differentiation of different cell types into these different tissue layers, and those tissue layers developing into separate organs. So we're starting to see the development of a gut, we're starting to see the development of not very obvious but we can pick out different organs that are developing at this time. So thats whats going on in our gastrula, theres also stuff going on on the outside. So theres all this other stuff, all these bits that are surrounding our developing embryo. And each of them of course has a job. The first is the Amnion which is this blue sac the amniotic sac. That water thats released when a woman goes into labor, whats happening when the water breaks is this amniotic sac breaks. So the amniotic sac is this fluid filled sac that the developing embryo is inside of and it cushions that embryo from impact. You've got your yolk sac which is where your blood cells are being produced. So its not really feeding you, its not providing you energy like it does in a chicken embryo, but its providing you with blood cells until your bone marrow develops, where it can take over. You've got your Allantois, thats going to become the blood vessels that connect you and your umbilical cord and connects you to your mom to get nutrients to get oxygen from her. And then finally this outer layer here, these little bits here, this is the Chorion and the chorion is what develops into the placenta. So that chorion is whats embedding into the endometrium of the uterus and develops into the placenta to help feed our embryo. The placenta is what keeps the fetus and the mother in close contact. There is not any bulk transport of materials across the placenta. So what we're doing is bring the blood supply of the fetus and the blood supply of the mother into close proximity, but they are not bleeding into eachother. So there is not blood from the mother flowing into the fetus going through the fetuses body and going back out to the mother. What we're doing is bringing these two pools of blood into close proximity and when they're in close proximity they can then exchange things like oxygen, nutrients, and waste to feed and clean the embryo. Some alcohol, drugs, can pass through the placenta into the fetal blood supply, a few diseases a few viruses like HIV is one of the virtues that can pass through the placenta into the mother. But by in large, very little is being transported across the placenta. We've got oxygen, we've got CO2, waste products and nutrients, sugars, proteins, basically thats it thats most of whats being transported across from the fetus to the other side, vice versa. We've got our developing embryo, its got an umbilical cord. That umbilical cord is the physical connection between the fetus and that placenta. So the placenta is wrapped around on the inside of the uterus, its got lots of blood vessels in it, and those blood vessels are all fetal and those blood vessels pour through the uterus and are connected to the fetal blood system the cardiovascular system. So over here these are fetal blood vessels embedded in our placenta and they are in close proximity to the internal blood supply to allow diffusion of these gases and nutrients back and forth. The placentas job is to be full of blood vessels to provide this area of exchange between the fetal blood supply and the maternal blood supply to feed our growing fetus. (cont. on next study guide question) We're going to finish talking about the development of our embryo all the way through the fetus, and into a newborn infant. We've been sitting here in the embryonic phase of development, this is the first couple of weeks since ovulation. In the first two weeks we went from just a single cell a Zygote, we divided into a solid mass of cells the Morula, and then that hollow ball the Blastocyst, which then started differentiating into some different tissue layers in the Gastrula stage. And so about two weeks we've gone through these steps, we've now got this inner cell mass that little blob thats at the interior of our blastocyst that is starting to develop into our fetus. Over the next 6 weeks, we're going to develop all of the organs, they're not going to be functional yet but we will have all of the organs and by the end of these first 8 weeks after ovulation the embryo is going to look basically human-ish. Humans are Chordates, thats the Phylum of animals that we are in, we are Chordates, and one of the characteristics of chordates mentioned was that we all have gills. We have lost our gills and we one have them as embryos. By the end of this embryonic stage, by the end of maybe the first 2 months after ovulation, we've got our end stage embryo. We're going to move into the fetal stage from here on. We've got a noticeable head, we've got an eye thats forming, we got hands with fingers, there is still little revenant of a tail down there and were starting to see the facial features some of the unique characteristics that you have that started showing up really early here at the 7.5-8 weeks past ovulation. Its also at this stage here at the end of the embryonic stage at about week 7, that gender differentiation occurs. Up until this point we all had the ability to become either male or female. So our sex differentiating chromosomes, the Y and the X chromosomes, have not been active yet. So up until this point all of us had, we only had one pair of gonads, but those gonads were not noticeably ovaries or testes. But in addition to the one pair of gonads we had two sets of tubes. We had one set of male tubes and ones set of female tubes. And our body was just sort of waiting to see which one of those tubes we should activate. And its the job of the Y chromosome to activate the male tubes of the reproductive system. In the presence of the Y chromosome, the gonads will differentiate into testes, start producing testosterone, which allows the male tubes to develop and the female tubes to degenerate. And in the absence of the Y chromosome, those gonads differentiate into ovaries and produce estrogen, which then causes the male tubes to degenerate and the female tubes to develop. So its right here at this 7 week stage that this is happening, where the function of the Y chromosome, the sex determining chromosome, starts becoming operative. Males and females organs are homonous, they come from the same tissues, and they develop in different ways based on the presence or absence of the Y chromosome. Here's a summary of our embryonic stage: moving from about four weeks old into 6 weeks old here, this is the end of the embryonic stage. We're about 1 inch big here at the end of the embryonic stage, the end of two months post ovulation. And from here, whats going to happen as a fetus, is were going to develop all those organs, we can have all the organs, all the organs are present and now they're going to start becoming more and more developed, more and more functional, and we're going to continue growing becoming obviously more human as we move forward. Thats 12 weeks post ovulation there at about 3-4 inches in length. So we finished our embryonic stage now we're moving into the fetal stage. This is where we become labeled a fetus. Our embryo looks human at the end of the embryonic phase, we're a couple of inches in length, all of the structures are present and accounted for, and now we need to grow them up and mature the body. So about 13 weeks, 3 months post ovulation, the cartilage skeleton which is remember our bones all started of as cartilage models, those cartilage bones are now being replaced with true boney material the calcium and collage matrix of true bone. And some of our organs are beginning to become active, particularly the kidneys and liver. These are important in detoxifying the blood, and as this fetus is growing its producing a lot of metabolic waste, and we need to be able to get rid of and process that waste and thats the job of the kidneys and liver. At about 17 weeks 4 months our face is approaching its final form, so this is a recognizable individual rather than some generic fetus and we're continuing to develop our various organ systems. The oocytes the ovarian follicles are forming in the female ovaries at this time as this process of developing the ovaries' process begins and all of those eggs will be finished by the end of pregnancy. 5 months 21 weeks is often when pregnant women often start feeling their fetus moving inside them. This is where muscle action of the fetus start becoming pronounced. And the baby's heartbeat can now be heard from outside the body if you have a stethoscope of the belly of a woman. At 6 months our fetus begins breathing, its not breathing air its just breathing the amniotic fluid of that water filled sac that its living in, its just breathing that in and out. Its starting to use the lungs, develop the muscles of the diaphragm in preparation for breathing air after being born. We're about a footlong fetus at this stage. So this is 6 months, everything is here and the goal is to get this fetus bigger and thats the goal of the next 3 months of pregnancy. The next 3 months there is continued growth and maturation of all the organs. This is a very active fetus so lots of moving kicking lots of muscle development. And its starting to respond to external stimuli, you can poke it and it will poke you back, you can sing to it and it will respond to different voices and different songs. And its eyes are starting to open and close its able to see, perceive light and dark a little bit. And its starting to develop its sucking response, that sucking response is going to be really important for milk consumption after birth and in these last 3 months is when that sucking behavior starts to form and the mouth muscles that are involved in sucking are starting to develop. And the finally at the end of 9 months or 38 weeks of post ovulation is where we say that these fetuses are competent to live outside of the mothers body. This is where they've developed to the point where they can survive in an outside environment. At this point is when the fetus, which has been somersaulting all over the place, now typically turns into a head down position, and that head is now resting at the bottom of the uterus, resting on the cervix which is the aputure between the uterus and the vagina. And its this resting on the interior side of the surface that is going to trigger actual childbirth the labor and contractions of childbirth. So to summarize this whole fetal period, this is a woman going from barely pregnant to just about to give birth. That belly size is not all belly, there is a lot of water in the amniotic sac, a lot of the volume that pregnant women have on their belly is the amniotic fluid space as well as supplemental fat which she's retaining to help nourish the baby. So we've got the babies head resting on the cervix inside the uterus and this triggers LABOR.

Understand how to construct and interpret a Punnett square

We use PUNNET SQUARES as a way of predicting, and using Menders hypothesis, predicting whats going to happen in the next generation. So we know what kinds of heritable units two parents in a cross have. We can predict the kinds of offspring we should expect and we can predict the relative frequency with what we should see those different kinds of offspring. So if we start at the beginning with Menders pure breeding lines, he has the purple individuals the purple pure breeding line, we see homozygous heritable units present in the purple pure breeding line. So we are a pure breeding line so that means we have two of these heritable units and each one of them are purple, we're gonna call that one big P for purple and the other heritable unit is also a big P for purple, so two big P's. And we also have the white pure breeding line, and the kind of heritable units present in the white pure breeding line are homozygous white, so we've got we'll call that a little p and a little p. The big P here indicates the DOMINANT form of this heritable unit and the little p stands for the non purple gene so this is the alternative to the Dominant form of P. So we use big P for the dominant form and little p indicates white which is the alternative to the dominant form. A Punnet Square is a little grid where we're looking at what happens if we cross two parents we cross a mother and a father of these two different lines. Lets say we have a purple pure breeding mother, she has a big P and a big P, what kinds of gametes can she produce? She has just one heritable unit, she can send this big P here to a gamete or she can send this other big P to a gamete, but those are both the same they're both big Ps. She only has these purple heritable units so she can only make these big Ps, and we put the heritable units that are present in each of the gametes that she can form at the top of these columns of the grid of the punnet square. So in one type of gamete she can make has just one purple heritable unit big P, and the other kind she can make is also a big P. Theres our mother. Our father now we put him on the side of the punnet square. What kind of gametes can he produce? He can produce white heritable units, he's a pure breeding white line and he only has these little p heritable units he only has the white heritable unit, and so his gamete types the only kind of gamete he can produce is one little p and another little p. So these are our gametes. We got the male thats providing these types of gametes (pp), we're got the female thats producing these types of gametes (PP). And now we're going to see what happens when we cross these two individuals, we're going to see what happens when we fertilize the females gametes with the males gametes. So the female provides this big P and the male provides this little p, so this is when the sperm and the egg cells are fusing together are fertilizing and creating a zygote. And these two Haploid gametes combine to form a Diploid zygote. *after doing the punnet square*, these are the offspring that are produced in the F1 generation. So these guys up here, this female and this male are part of the parental generation. And its offspring that they can produce are all represented here inside this punnet square. These are the heritable units that could be present in the F1 generation. So Mendells next cross is he took in the parental generation a pure breeding male and a pure breeding female and produced the F1 generation. In his next cross he took the F1 generation and he crossed two F1's. So the F1's the identity of the heritable units in the F1 generation are just these ones up here resulting from the first punnet square. So that would be Pp, Pp, Pp, Pp. All of these F1 generation individuals are heterozygotes, they all have a purple heritable unit and a white heritable unit. And so this cross is going to be a female heterozygote and male heterozygote. For our female, what kinds of gametes can she make? Remember Mendells hypothesis was that this pair of heritable units, the Ps, they separate and only one of those heritable units goes to each of the gametes. And so she a big P and a little p purple and white heritable units and only one of them is going to go to a given gamete. And so she produces some gametes that have a big P and some gametes that have a little p. And the male is the same, he's also heterozygote, he produces some gametes with a big P and some gametes with a white little p. Now we take these gametes and we fertilize we make our F2 generation by fertilizing these gametes with eachother. Our first cross of this punnet square would be Homozygous dominant. We got two big P's we got two purple so thats what we got we got two purple heritable un its. So with this next one we got a father providing a big P and the mother providing a little p, so we get a heterozygote here. In this next case we have the mother providing a big P and the father providing the little p, so another heterozygote. And in this next case both the mother and the father are both providing little p's the white heritable units. So in our first cross when we made our F1 generation we crossed a pure breeding white with a pure breeding purple line, and what we got were a bunch of heterozygotes. And Mendells hypothesis that one of those heritable units is dominant and overwhelms the influence of the other, would predict that those that all those off spring all those heterozygotes should display the dominant appearance, so the purple appearance which is the dominant type in this situation, would all appear purple, so all of the individuals in our F1 generation appear purple as for Mendells observations. So when you cross these two F1 individuals these two heterozygote F1 individuals, you get 3 out of 4 of the offspring that are produced in that cross are purple. So we get 3 purples for every white one that we get, so we have 75% of our offspring from this F2 generation our purple and 25% of them are white. In this next cross we're going to do a male heterozygote so he's got one P and one p. And lets use a female homozygote with two big P, so two purple heritable units. Each of the males gametes only has one of these heritable units, so we got purple heritable units he produces some gametes, and a white heritable unit for some other gametes. The gametes that the female can produce, she only has the big P purple heritable unit so she ca only produces gametes that also have just one of those purple heritable units. If we cross these two and fertilize with the male gametes we get two purple units. If we cross with the next ones we get also two purple units. The next one would be a purple and a white so it would appear purple. And the last one would also be a purple and a white. All of them will appear to purple. Two of them are purple heterozygotes, and two of them are purple homozygotes.

Understand the concept and consequences of trophic transfer efficiency

When you eat something, you're taking in biomass. You're taking in an amount grams/kilograms of food. And from that food, you're digesting out the nutrients the macro and micro nutrients that are present in that food and some of those things are being incorporated into your body. So when a predator, you, when you consume something there are a number of steps from killing some food to growing your body. The first thing that happens is that u kill some food, lets say a cow, and from that cow you can make a burger, but you can't eat all of a cow, there is some biomass some of the weight some of the kilograms of cow that are left behind, you cannot eat cow bones we cannot consume that mass the weight of bones are not something that we can eat. And there is some biomass some of this weight of cow thats left behind. Some of what you eat's, some of that burger you eats biomass gets digested, so some of but not all of the macronutrients the calories the carbohydrates proteins and fats that are in that burger get digested into you they get absorbed into your body. Some of it doesn't, some of the mass of that you eat gets excreted. Things like fiber is not digestible, if you eat a lot of fiber you have a lot of biomass that is being excreted that is not being digested. But even if you're eating a low fiber diet not all of the carbohydrates the proteins the fats are going to be digested. This is because your body, although its absorbing nutrients, is not perfect. You're not getting 100% of the possible nutrients into your body when you eat. This is why manner is a good fertilizer, cow poop or human poop makes a good fertilizer because theres still a lot of organic material left after its being passed through the body. So some of the biomass you've consumed gets lost because you can't absorb it. And then of what you absorbed, the nutrients that you absorbed, some of them get used to build your body. We get to use some of those macro and micro nutrients to build the physical structure of your body, particularly when you're young. By the time you reach maturity, you are basically done with biomass growth, you're not really adding much mass to your body you're not growing from here on. Most of what you consume the calories of which you take in, are now used for metabolism burned for metabolism. They're used to power the body that you've built, not to build new biomass. So that original cow biomass that you have now ingested and not thrown away, that you've absorbed and not pooped out, and not been using for growth, is not going to respiration is going to metabolism and energy. So we've got this flow of energy that we think of as the calories that are in the nutrients you're consuming, we think of them just as their pure energy. That energy is flowing from the cow, from the original biomass of the cow, flowing into your body with a few losses along the way. We've got this wasted loss in what you can't consume which is what you can't absorb, and whats not going to biomass growth. But this flow of energy through different organisms is what we use to build a food web. You've got the cow that is receiving energy from the grass, the grass binds up solar energy into carbohydrates, so those carbohydrates those calories are flowing into the cow. The cow then has those calories, and if you eat the burger made out of the cow, that energy is now flowing into your body. But again from those transitions from one species to the other there are these losses. These areas where biomass and energy is lost along the way. So if we start with some grass, one acre of grass, makes some amount of biomass. So if a cow wants to come along and eat some of that mass, so you put a cow into your acre of grass in that pasture and that cow is eating grass, some of that biomass of the grass that the grass is producing is killed. So this high amount is cut by the cows mouth, some of that amount is consumed so maybe the cow is dropping clips of grass out of its mouth so its not perfectly able to consume everything that it kills. Of what is consumed some is assimilated, some is lost not able to be digested, and then some of that assimilated energy is used for growth, and the remainder is used for metabolism. At each of these steps we can measure this INEFFICIENCY, the amount of biomass that is consumed divided by the total amount of biomass that is available. This gives us our ingestion efficiency. We've got assimilation efficiency, how much is absorbed how many calories that are absorbed divided by how many calories are consumed. Our metabolic efficient is finally how much biomass of cow is produced for every amount of energy that is assimilated into the body. So we've got these discrete efficiencies that we can measure, or we can call it altogether we can measure how much grass there is how many kilograms of grass there are, and how many kilograms of cow we can produce from those kilograms of grass. This whole step down from grass to cow is called TROPHIC EFFICIENCY. This is our production at one level on a food web on a food chain provided by the amount of production at the next level down. Essentially how many grams of cow can we produce per gram of grass. And then similarly if you eat that burger made out of that cow, we got the same idea of these step downs that can all sum up to trophic efficiency. How many grams of you can be produced per grams of cow. If we look at all food webs on the planet, all species that have been measured, the average Trophic Efficiency for all consumer species is about 10%. So averaging all species, if you have one individual thats consuming another, so one cow thats consuming grass, that total trophic efficiency is about 10%. So if we assume 10% trophic efficiency, which is a good general place to start, and we assume that in our field in our pasture our grass is growing at a rate that produces 100 grams of grass in every square meter per year, how much cow how many grams of cow can we support with this pasture, how many grams of cow per square meter per year can we grow? 10 grams would be the amount. Because 10% of 100 is 10. So our trophic efficiency is how much cow can we produce per grass. So if we're producing 100 grams of grass per square meter per year, then our 10% trophic efficiency is 10% of that production of 100 grams, so 10% of 100 grams is 10 grams. So we're producing 10 grams of cow in a system like this where we've got this 10% Trophic Efficiency and 100 grams of grass produced per square meter per year. If you then come into that system and consume that cow, how many grams of human could you produce per square meter per year from that pasture? if you're eating cow that is eating that grass. The answer to that would be 1 gram. That is because the cow that produced 10 grams from that 100 grams of grass only has 10 grams to offer to the human. That is because that 100 grams of production of grass, a 10% trophic efficiency to make a cow gives us 10 grams of cow that are being produced from that field. And if we stick with the standing Trophic Efficiency being 10%, from cows to humans, we take 10% of 10 grams, which would be 1 gram of person per square meter per year. But if say this person is not eating cow, we're not growing cows in this grass pasture, and our human instead eats the grass, then how many grams of humans can you produce in this field if the human is eating the grass grown in the field, not eating the cow? Being that there is 100 grams of grass, our answer with the constant trophic efficiency of 10%, would be 10% of 100 grams, in total the answer being 10 grams. If we want to continue producing food for people, then one of the ways that we can do it is by increasing our trophic efficiency, to use the same land to feed more people. This is one of the mechanisms that we can allow more calories to be flowing into humans given the same space of land, is by cutting out the middle man. By cutting out the middle man refer to the last question. We wanted to see how much human can be produced from eating the grass, not eating the cow thats eating the grass because we cut that out. So cutting that out made it so we only had to consider the trophic efficiency with the 100 grams of grass, rather than the 10 grams of cow that gets produced from the 100 gras of grass. So cutting the middle man out would be cutting out the cow and the animal sources in our diets. This is the advertisement for a reduction in the amount of meat that particularly developed countries consume, particularly developed countries like the US consume a large quantity of meat. And that large quantity of meat, just by nature of consuming something that is not a plant, means that we have one other individual that is losing biomass is losing calories through this trophic efficiency graph than we otherwise would if we were feeding directly on plant material. This is one of the ways that as we approach our human carrying capacity that we can continue to feed the world, is by switching to a lower and lower, on the food web, so that our energy lost is minimized. So converting to a vegetarian diet would be beneficial in terms of human carrying capacity.

REPRODUCTIVE Know the organs of the male and female reproductive systems, and understand their functions

Whoever makes the larger of the two gametes, we call female. IF they produce the largest gamete we call them female, and the smaller gamete is male. A gamete is a cell that is used to fuse with another gamete to then form a new organ. So at the end of meiosis we end up with these haploid cells that typically, atleast in animals, typically those haploid cells are also gametes. Those haploid cells will then go and fuse with another haploid cell to create a diploid offspring. So those are gametes. So female humans produce the larger of the two gametes we call them female by definition by the size of the gamete. And then men producing sperm very small cells are male. So female gametes are much larger than male in humans. The function of the reproductive system is to make these gametes and then get them together so that these gametes can fuse with eachother. Make these gametes, get them in a place where they can fuse, and create an offspring. Other functions of the reproductive system are triggering puberty. There is a lot of hormonal control, a lot of endocrine function going on in the reproductive system. So triggering puberty, stimulating the secondary sex characteristics- so in men that would be things like voice changes, muscle development, and hair all over the place. In women that would be a little bit of voice development, a little bit of muscle development and primarily some body remodeling so breast development, some hip reshaping- these are the secondary characteristics. Also maintaining reproductive ability- monitoring and maintaining all of the reproductive organs is the function of those reproductive organs themselves. Reproductive organs would include gonads, these are the things that are actually producing gametes. So these are the organs that are making either the ova or the sperm. Then you've got ducts which are involved in moving this gametes from where they're produced at the gonads to somewhere else. You got accessory glands that are helping everything along the way and then you got some support mechanisms that help with delivery of gametes and helping those gametes grow. MALE reproduction system goals are to make sperm, store sperm until needed, and then deliver sperm when needed. What we need is our basic anatomy, we have our gonads down here- the testes. The testes there are the gonads producing the gametes/producing the sperm. And then you got some ducts that are carrying it from the testes up and around and down through the penis for delivery. In the testes, the biggest space occupying piece of the testes is all these wiggly tubes. All these wiggly tubes are called the seminiferous vessels or seminiferous tubules. And they are where the production of sperm actually happens. So new cells are going through meiosis and are forming into haploid sperm cells right in here in this largest part here of the testes. The testes, the actual organ, the gonad, is housed in men in this sack of tissue called the scrotum. The scrotum is a temperature regulator. So the sperm are developing down here in the testes, and their optimum temperature for developing is lower than body temperature. It's the job of the scrotum to adjust that temp to keep them in that optimal lake. When cold, bring the testes up into the body to keep the testes warm in the body, and if you're really hot the scrotums muscles will relax and let them hang away from the body so that the testes can cool off. So down into the seminiferous tubules we got the tubes of the tubules, this is the start of the duct network thats gonna carry these sperm out of the male body and as we go into the tissue here we're moving up into these progenitor cells. These are the parent cells, the ones that are going to go through meiosis to form sperm cells. So these cells start off up here, some of them will go through mitosis to create identical diploid copies and then one of those daughter cells can then enter meiosis to get some more gametes at the end of it while retaining one of the original identical versions of that cell for then later sending one of those cells in through meiosis. As these cells go through meiosis, the ploidy reduction, they move further and further down in the tissue towards the tubule, the open spot in the tubule. By the time they reach this point here these cells have undergone the complete meiotic division. So their ploidy is now in half, but they don't look like sperm yet, they need a little more development before they get the classic head and tail shape of a sperm cell and that happens right when these sperm cells are about to be released. When they are about to be released they lose a lot of their organelles, so a lot of the standard pieces of cells, all those endoplasmic reticulum, the golgi apparatuses, all of those are lost and all they're left with is a little bundle of DNA that haploid nucleus and a tail with some energy to swim the tail so that these sperm cells can move. So these cells can now drop into the open space of the duct network. All that we got left is at the head of the sperm cell this is the nucleus, so all of the genetic information is packaged up there. The long tail, and in order to move that tail we need ATP, and we generate that with mitochondria which is packaged at the base of the tail. Then there is a hat on the outside of the head called the acrosome. This hat is made up of proteins that are digestive proteins. The egg cell has a protective coating and its the job of the acrosome to digest its way through the protective coating so that the nucleus of the sperm cell can penetrate into the egg to fertilize it. So we have sperm cells, now we have to get them out of the body. We have production at the seminiferous tubes, then there is a protective outer layer of the testicle called the epididymis. So the sperm are made in the seminiferous tubes then they are then stored in the epididymis where they continue maturing, they move up the vas deferens up into the body cavity where they are being transported and stored, packed away and then moved down the ejaculatory duct that connects this whole system into the urethral system. This is the unique difference of men and women, these two systems are coming down into one duct and then flowing out. Women have two different eternal openings for the reproductive and urinary systems whereas men only have one for the two. Then down through the urethra delivering sperm to the outside. Sperm is carried through fluid in the same way we need blood plasma to carry blood cells. Semen is the full product being released by males. The seminal vesicles, prostate gland, and bulbourethral glands are all producing various amounts contributing to the total volume of semen. Sperm only makes up 5% of the total volume of semen. These other factors are adjusting the chemical environment that sperm swim through. The three all produce a slightly alkaline fluids, higher ph materials to help neutralize the fluid that the sperm are swimming through as they're moving through the female reproductive tract. The seminal vesicles also help suppress the immune system of the female body that the sperm are going to be going into. Now we have to get these sperm from the male body to the female body and that is the job of the penis. When ejaculating, 300 million sperm cells come out each ejaculation. FEMALE reproductive goals are to make the gametes so make the eggs the oocytes. You gotta move those oocytes around and then you also have to be able to receive sperm, and then females protect their embryos internally and then get it out of the body once its developed enough-giving birth. The goal of the female gamete, of the egg, is to be large, healthy, and be able to survive as long as possible by itself. Its the job of these follicle cells to feed that egg cell. The follicle then breaks open and discharges the egg out of the ovary here, this is the moment of ovulation, when the egg cell is released out of the ovary. And then the follicle cells are retained for a short period, these follicle cells here, this blobby yellow thing, are the remanent of the follicle and its job is to help maintain pregnancy. If this egg goes on and gets fertilized, its this follicle that produces hormones that help maintain the pregnancy. If fertilization doest occur, the follicle cells degenerate, they aren't producing hormones, and so the egg cell eventually gets discarded on down the way. The female gonad, the ovary, is not directly connected to the tube that the egg flows through. The fallopian tube, the name of the duct that the egg flows through, has an open ended funnel that the ovary sits down into but does not seal off. So this egg is released, dumped out into this open cavity and then hopefully swept up into the fallopian tube into this duct. Our goal is to get this egg cell into the fallopian tube and its here where fertilization happens. If fertilization for this egg is going to happen, it'll happen in this fallopian tube. So sperm are introduced into the female body by way of the penis, into the vagina, they swim up through uterus, up through the fallopian tubes to meet the egg here in the fallopian tube. So we got our ovary here dumping eggs into the fallopian tube, simultaneously you got sperm that are coming up through the vagina, into the uterus, trying to get up through the fallopian tube to meet an egg cell, if they do, they fuse, they form a diploid zygote. The first stage of embryonic development. So we got the egg releasing from the ovary here as a result of ovulation, we got little sperm cells that are trying to penetrate into the egg, if one does you now got a diploid one day old cell zygote, and this little cell is going to migrate as it divides into a larger and larger number of cells down the fallopian tube and into the uterus. And its here in the uterus, about a week after fertilization, its here in the uterus that this little developing embryo embeds itself into the wall of the uterus. The uterus is a special organ, essentially a very large and muscular tube, like an enlarged version of the fallopian tube, but this is the place where a developing human embryo develops. That little cell embeds itself, digs into the wall of the uterus, and then it starts secreting hormones, those hormones are what recruit a placenta to it. If that cell does not fertilize-that egg does not fertilize and does not burrow itself into the lining of the uterus, then all of this developing lining of the uterus is shed out of the body, this is menstruation. This lining of the uterus is what is being shed by the female body monthly if there is not an implantation of a developing embryo.

Know the definition of evolution, including understanding what evolution is not

With natural selection, operated on the fitness level of individuals, we can get EVOLUTION. Evolution is a change in allele frequency through time. Any change in allele frequency is called Evolution. So our example of the labrador puppies, the labrador puppies alleles increasing in frequency through time relative to the other breeds of dogs is an example of evolution. We have a change in allele frequency through time. One of the mechanisms that can lead to this change of allele frequency is this natural selection. The selection of fitter individuals of individuals that either reproduce better or survive better than other individuals in the population. Mutation is another mechanism for evolution. Mutations can lead to a different allele, and because its a different allele its a change in allele frequency and is an example of evolution. And what we today in human population is an increase of blue eyed color individuals which results from a change in the allele frequency among a population. The population of humans remains the same though, its just allele frequency variation within a population. That is an example of recent human evolution. This would be an example of MICROevolution. What we tend to think of when we think of evolution is MACROevolution which is when differences in allele frequency add up through thousands and thousands of years we get something that is so very different it is phenotypically so very different in appearance behavior and function that it is no longer the same species. It can no longer interbreed with the original species. Macroevolution is the accumulation of these small changes in allele frequency through time.