Biology - Unit 1a: Lactase Persistence

Mutation

a random change in your DNA

Lactose

a special type of polymer found in milk called a disaccharide, a sugar polymer made of monomers

Lactase

an enzyme that catalyzes the hydrolysis of lactose to glucose and galactose.

Fitness

an organism's ability to survive and produce

Lipids

Biological molecules are made of carbon, hydrogen, and oxygen atoms

Proteins

Biological molecules are made of carbon, hydrogen, oxygen, and nitrogen atoms

Nucleic acids

Biological molecules are made of carbon, hydrogen, oxygen, nitrogen, phosphorus atoms

Carbohydrates

Biological molecules made of carbon, hydrogen, and oxygen in a ratio of roughly one carbon atom to one water molecule

TRUE or FALSE: Natural Selection takes place over the lifetime of an individual.

False: One of the four conditions for natural selection is inheritance, meaning that in order for it to occur and spread, the trait must first be passed through many generations.

Know the order of the taxons from domain to species.

From to most inclusive to least inclusive it's: Domain, Kingdom, Phylium, Class, Order, Family, Genus, then Species.

Explain the genetic reason for making lactase and how does it relate\ to being lactase persistent or lactase non persistent.

Lactase is produced so that infants are able to digest milk as babies. In people that are lactose intolerant, the lactase gene gets "turned off" sometime after breastfeeding stops, whereas in people who are lactose tolerant the lactase gene is permanently "turned on."

Population

a group

Galactose

a monosaccharide in lactose

Glucose

a monosaccharide in lactose

Be able to explain how lactase persistence appeared then spread through a hotspot population. Include the following concepts: 1. There is heritable trait variation within a population of organisms. 2. Something changed in the environment that the population of organisms was in (or went into). 3. The environmental change put selection pressure on the population of organisms so that some trait variations had a competitive advantage (increased odds) for surviving over time. 4. When there are available resources, those organisms that survive will reproduce, making more organisms with the same variation(s)as the parent(s). Organisms that die cannot reproduce and cannot pass on their variations.

1. At some point after breastfeeding stops, most humans lose the ability to digest lactose. However, in some parts of the world most of the adult population continues to digest lactose. In people who are lactose intolerant, the lactase gene gets 'turned off", whereas in people who are lactose tolerant the lactase gene is permanently ''turned on." This trait was passed on over generations so that now about ⅓ or 33% of the population can digest milk in their adulthood. 2. Lactose tolerance (or lactase persistence) is found in pastoralist populations. The hotspots are located in most of Europe (especially concentrated in the west), the area of Africa directly beneath europe (northwest), and the Middle East region (spreading a little into eastern Africa). About 7,500-9,000 years ago, certain groups of people began domesticating cattle and drinking their milk. In such cultures, the lactase-persistence trait increased in frequency over time. Occasionally, the environment would change (droughts, floods, etc.) and famine would sweep across the area. 3. Should an area go into famine, most of the people would be reliant on milk as a source of nutrients. Being lactase persistent in a dairying culture and starvation conditions gives you a better chance of survival since you are able to digest milk. Those who are lactose intolerant would not be able to do so, and therefore become extremely dehydrated and starve to death. 4. As a result, those who are lactase persistent have increased odds of surviving and passing on the trait. The lactose intolerants that die cannot reproduce and pass on their variations.

Dehydration synthesis

A chemical reaction that involves the loss of water from the reacting molecule or ion

Polymer

A large biological molecule that is a long chain made up of monomers

Hydrolysis

Any chemical reaction in which a molecule of water breaks 1 or more chemical bonds

What are the four macromolecules, their functions, their monomers and polymers?

Carbohydrates: Polymers - Polysaccharides Monomers - Monosaccharides Function - A quick source of energy Examples in food - Pasta, bread, sugars Proteins: Polymers - Enzymes Monomers - Amino acids Functions - Muscle building, make up enzymes, support the immune system Examples in food - Meats, beans Lipids: Polymers - Phospholipids and triglycerides Monomers - Glycerols and fatty acids Functions - Insulation, a long term source of energy, make up cell membranes Examples in food - Butter, oil Nucleic acids: Polymers - DNA and RNA Monomers - Nucleotides Functions - Contains genetic information Examples in food - Any type of life

Enzyme

Enzymes are the polymers of protein that act as catalysts in chemical reactions

Variation

Individuals in a population or group differ in some trait of interest

What is the relationship between a monomer and polymer?

Polymers are long chains of repeating molecular subunits, or building blocks called monomers

Monomer

Repeating molecular subunits, or building blocks that make up polymers

What role does the environment play in natural selection?

The environment acts as the constraints or the conditions that all organisms inhabiting it must live under. This will determine the food source, weather, etc. and most importantly, the competition. Undergoing natural selection, those who are most compatible with the environment will survive.

What is a scientific name? How do you write it?

The genus and species to which an organism belongs.

Active site

The part of an enzyme where the substrate binds and where the chemical reaction occurs.

What is the difference between random mutation hypothesis and acquired mutation hypothesis? Which one represents Darwin's theories? Which one represents Lamarck's theories? Which one is accurate?

The random mutation hypothesis explains evolution as a result of random mutations that give certain members of a species an advantage in survival. Therefore, more with the trait will live and those without will die off, leaving those with the mutation to pass it onto their offspring. In this interpretation of evolution, the process takes place over generations. This was Darwin's theory. The acquired mutation hypothesis explains evolution as a result of what an organism wants or needs. Then the trait will be intentionally acquired during their lifetime and passed onto their offspring. This is Larmarck's theory. Darwin's theory is more accurate.

Substrate

The reactant molecules that enzymes grab/bind to

Explain what symptoms someone who is lactase non persistent experiences after eating dairy and why.

The various gasses in the large intestine produced by fermentation can cause abdominal pain, bloating, flatulence, and diarrhea.

TRUE or FALSE: Natural Selection takes place in a population

True: Natural selection weeds out the most beneficial mutations to the survival of a species and spreads it through the population by passing it down to the offspring and through generations.

What are the four conditions for natural selection? Be able to identify each condition in a new example of natural selection.

Variation - Individuals in a population or group differ in some trait of interest. Example: Lactase persistence vs. lactase inpersistence Inheritance - The variation in the trait of interest is at least partially inherited (passed from parents to offspring). The variation stems from random mutations and the recombination that accompanies sexual reproduction. The genetic variation may have arisen many generations in the past. Example: The lactase persistent gene was passed onto the offspring Differential survival and reproduction - More offspring are born than can survive, resulting in competition among individuals within a population. Some individuals with a particular trait are more likely to survive and/or have relatively more offspring compared to individuals that do not have that trait. Selection depends on the specific context of a species. Traits that are beneficial in one environment may cause problems in another environment Example: It increases the rate of survival during famine in a pastoralist society Adaptation - The frequency of the trait that helps individuals survive or leave more offspring will increase in the population over time, as will the alleles that affect the trait. This process can take many generations and extend over very long periods of time. Example: Seeing that it's beneficial, more people became lactose tolerant over time

Denatured

When an enzyme is deformed due to being in an unnatural ph and temperature level. Then it can't bind to substrates.

How is lactose digested in those who are lactase persistent? What about those who are Lactase non persistent?

When someone who is lactase persistent consumes lactose, the sugar molecule is digested and broken down by the enzyme called lactase into its two monosaccharides---glucose and galactose. When someone who is lactase non persistent consumes lactose, the undigested lactose passes from the small intestine to the large intestine, where it is broken down by gut bacteria through the process of fermentation, which produces various gasses in the large intestine.

Fermentation

fermentation is the process in which lactose is broken down by gut bacteria, producing various gasses in the large intestine, which can cause abdominal pain, bloating, flatulence, and diarrhea---all symptoms of lactose intolerance.

Competition

interaction between organisms, populations, or species, in which birth, growth and death depend on gaining a share of a limited environmental resource

Catalyst

substance that speeds up the rate of a chemical reaction

Activation energy

the amount of energy that must be put in for a reaction to begin

Evolution

the process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth.

Natural selection

the process whereby organisms better adapted to their environment tend to survive and produce more offspring