Chapter 1,2,3, and 4 Biology
Explain the structure of lipids and relate it to their function
3 Fatty acid chains made up of hydrocarbon bonds attached to a glycerol molecule Lipids saturated with hydrogen, mean hydrogen is apart of every possible carbon bond, would cause the fatty acid to be linear, compact, stacked, and rigid. Lipids with double carbon bonds instead of hydrogen bonds, creates a kink in the fatty acid chain causing it to be more fluid Lipids can cause the cell membrane to become more fluid or solid based on changes in temperature in the environment. Cells cannot create more double bonds between carbon to keep the membrane more fluid and resistant to stiffness in cold temperature, vice versa.
Explain the difference between hypothesis and theory Outline the scientific method
A hypothesis is a researched based explanation (agrees with current evidence) of an observation but it needs to be tested. Its based on generalized observations but is more specific than a theory. A theory is a more generalized explained that is supported by a large body of scientific data. New hypothesis can form based on a generalized theory Scientific Method: 1. Observation is made and a question is formed based on the observation 2. A testable and specific hypothesis is formed from research to explain the observation. A statistical hypothesis includes Null hypothesis (no correlation between variables) and Alternative Hypothesis (there is correlation between variables) 3. A prediction is made based on the hypothesis 4. An experiment is designed to test the hypothesis using control variables (participation or no participation), experiment variables (receives the treatment/test), dependent variables (what is being measured, unaltered), and independent variables (what is altered/effects the dependent variable) 5. Data is analyzed and gathered to form a conclusion. A theory can be formed with repeated testing, the hypothesis can be modified if it's is not accurate or new evidences arise, or new hypothesis are formed.
Some fats, like oil, are liquid at room temperature, while others, such as butter, are solid. A) Explain how the structure of these molecules determines whether they are liquid or solid. B) Somethings, such as sugar, easily dissolve in water while others, like oils, don't dissolve in water. What aspect of the molecule's structure determine whether it dissolves in water or not?
A) Butter is a saturated fat. This means that every possible bond that can be filled with a hydrogen, has a hydrogen in it. As a result, the molecule is very linear and easily stackable. Thus, at room temperature you can pack multiple molecules together and have a solid structure. On the other hand, oils are unsaturated fats. They contain double bonds between carbon-carbon. These double bonds create kinks in the molecule, making them harder to stack. As a result, the molecules are looser at room temperature and thus, the structure is more fluid.B) Polar molecules such as water have an uneven distribution of charges, they have some parts of the molecule that are slightly positive and other parts that are slightly negative. Polar molecules have a large number of atoms that are highly electronegative, such as Oxygen, or highly electropositive such as Nitrogen. Polar molecules can form hydrogen bonds with each other, as the negative side of one molecule interacts with the positive side of the other molecule, usually a Hydrogen, and thus these interactions are called hydrogen bonds. Polar molecules can dissolve in water as they can form hydrogen bonds with water molecules. Non-polar molecules have an even distribution of the charge and cannot form hydrogen bonds, so they cannot dissolve in water and are called hydrophobic.
Both, cellulose and starch are composed of many glucose molecules joined together in long chains. A) Indicate what type of biomolecules these are, identify the monomer and the polymer. B) Us, humans, we can digest starch but not cellulose. Why can't we digest cellulose if it's composed of glucose just like starch? Explain, making a connection between structure and function of biomolecules.
A) Cellulose and starch are examples of carbohydrates. Moreover, they are polymers, made up of multiple smaller building blocks. In the case of starch and cellulose, the building block is glucose. Glucose is the monomer.B) Although cellulose and starch are both made of glucose, the way the glucose molecules are linked is different between the two. In starch, the glucose molecules are all oriented in the same direction, while in cellulose, each molecule is upside down compared to the previous one. As a result, their structure differs enough that humans cannot digest cellulose despite being able to digest starch.
List the characteristics shared by all cells
Basic unit of life Only cells can reproduce cells All living things are made up of 1 or more cells
Contrast the structure of DNA and RNA
Both are in all organisms (prokaryotes and eukaryotes) DNA is in the nucleus (eukaryotes) RNA can be inside or outside the nucleus (eukaryotes) DNA code/holds information for building proteins DNA is double stranded with nucleotide (strains) running anti-parallel RNA is single stranded DNA has deoxyribose RNA has ribose Bases in DNA include ATCG (apple in the tree, car in the garage) Bases in RNA include (AUCG (apple under the tree, car in the garage)
Describe the differences between prokaryotic and eukaryotic cells
Both have cytoplasm, ribosomes, cell membranes, DNA Prokaryotes are always unicellular Prokaryotes don't have a nucleus Prokaryotes don't have organelles Prokaryotes have pili (hairs) and a capsule
For each macromolecule type, name the polymer they form, the monomers that composed them
Carbs > monosaccharides (alpha glucose > starch/glycogen > Found in energy storage areas of potatoes or in the structure of cellulose in the cell walls of plant cells Nucleic Acid > nucleotide > DNA strand > Found in chromosome or mRNA Proteins > Amino acids > Polypeptides > Found in enzymes, myosin, kerratin, hemoglobin Lipids > Fatty acids > triglycerides > Found in butter, oil, phospholipid cell membrane *Removing water from a molecule allows monomers to bound to make polymers* A monomer is a building block for a polymer
Summarize the (6) common themes in biology and explain how each of those themes helps us understand life.
DIEEES Cell Theory Cells are the basic units of life All living things have one or more cells Only cells can reproduce other cells Central Dogma (DNA) 1. DNA is the basic unit of inheritance. It holds genetic information that is inherited from the parent to the offspring. DNA has all of the instructions to produce proteins that form the organism. mRNA carries instructions from DNA to signal Ribosomes to produce proteins. DNA determines how amino acids will be sequenced and RNA tells ribosomes when to create proteins Interaction All living organisms interact and have relationships with other living organisms. Evolution All living organisms evolved from a common ancestor which explains the diversity and similarities between living things. Emergent properties Emergent properties are present at each system level. As basic levels interact to form more complex levels, basic properties remain but new properties emerge Energy All living organisms require energy to live and produce energy. Eating and sun light are sources that allow for energy production. Structure and Function Structure and function are closely related:
Explain the organization of the eukaryotic cell and its advantages
Despite their larger size, eukaryotic cells are still efficient despite being much larger than prokaryotic cells due to the fact that they have organelles with specialized functions. Eukaryotic cells have a true nucleus, which holds the purpose of secluding DNA related functions. Likewise, they have lysosomes specialized on digestion, ER for lipid metabolism, mitochondria for energy production, etc. Eukaryotes have membrane-bound organelles that are like chambers for specific reactions. These chambers allow increased efficiency allowing multiple reactions to occur at the same time in separate compartments, thus making the eukaryotic cell more efficient than the prokaryotic cell.
Compare the structure of plant cells to animal cells
Each have the same structures and organelles except for: CCC Plants don't have centrosomes Animals don't have cell walls Animals don't have chloroplasts Plants don't have cilia, animal cells have cilia in the respiratory tract
Explain why the concept of evolution is so important for understanding biology
Evolution explains the wide diversity of species that exist, but also the similarities between these species (such as skeletal structure). This is important to understanding biology because all living organisms evolved from a common ancestor but developed diversity from the ancestor by adapting to their different environments.
Explain what makes a molecule either hydrophobic or hydrophilic
Hydrophobic molecules are non-polar and cannot form hydrogen bonds with water molecules and repel water (oil, large fats). Hydrophilic molecules are polar and can form hydrogen bonds with water molecules (dissolve in water) (sugar,
Categorize the main macromolecules living beings are composed of
Lipids, Proteins, Carbohydrates, nucleic acids
Explain the concept of emergent properties and how it applies to living things
New properties emerge in organisms when basic levels of the organism interact to form more complex levels increasing in hierarchy. New properties formed when components interact, but is not the sum of the two parts combining (When atoms combine to form molecules, they keep their atomic properties, but they will be able to do new functions. The new functions are not the sum of the 2 atoms combining.) All life including complex human beings began as a basic atom
Describe the function of the main cellular organelles and cellular structures
Nucleus - stores DNA Nucleous - creates ribosomes Ribosomes- create proteins Golgi appartus - folds and shapes proteins for specific functions ER - transports substances via vesicles Mitochondria - produce ATP to energize the cell Lysosomes specialized on digestion ER for lipid metabolism
Explain the difference between polar and non-polar bonds
Polar molecules are have uneven distribution of charges (can be positive or negative) where one part of the molecule is slightly positive and the other part is slightly negative. They can form hydrogen bonds. (Includes sugar, ions, water). Polar molecules can dissolve other polar molecules because of the hydrogen bonds they form, so they are hydrophilic. (Ex. Water is a neutral molecule, but the electrons spend more time around the oxygen atom because oxygen has a higher electro-negativity than hydrogen, making that side more negative and the hydrogen side slightly more positive.) Non polar bonds have an even distribution of charges and therefore cannot bond with hydrogen. Non polar molecules cannot be dissolved in polar water and are hydrophobic (these can cross the cell plasma membrane through simple diffusion, small fats, gases, non-polar molecules)
Describe the levels of protein structure and how each level is determined
Primary structure is sequencing of amino acids as determined by DNA instruction Secondary structure is the folding of proteins due to interactions between the amino and acid group (carboxly) forming hydrogen bonds. It can be a alpha helix or beta sheet Tertiary Structure proteins folding onto itself due to interactions and weak bonds with the R groups forming hydrogen bonds, ionic bonds, van der waal interactions (hydrophobic/hydrophilic interactions), or di-sulfide bridges. Quaternary structure is the when separate proteins or peptides bond to form a larger protein
Explain and compare the processes of osmosis, simple diffusion, facilitated diffusion, and active transport
Simple diffusion is the net movement of molecules down a concentration gradient, meaning that the molecules move from a high concentration to a low concentration gradient; simple diffusion is used to transport small, nonpolar molecules, which can freely cross the plasma membrane.Osmosis is a special case of diffusion that only applies to the movement of water molecules across a semipermeable membrane. Water molecules have positive net movement from a solution with low concentration of solutes (hypotonic) to a solution with higher concentration of solutes (hypertonic) until they reach an isotonic solution. Note that water moves in the opposite direction in which the solutes would have moved.Facilitated diffusion is the process by which molecules that are not able to go through the membrane directly, are transported across the membrane with the aid of proteins without the need of input of energy. Facilitated diffusion doesn't require energy because molecules move along with the gradient, from a high concentration to a lower one. It is used for larger, polar molecules and charged ions.Active transport is the process by which molecules are moved against the concentration gradient, from lower to higher concentration, therefore ATP, energy is necessary. Active transport needs both, a source of energy such as ATP, and a carrier protein to do the work. Either directly as NA/K pump or indirectly as coupled transport when ATP is released by diffusing molecules which are transporting themselves against the gradient in the same direction or as counter transport when two molecules move in opposite directions. An example of facilitated diffusion is Na/K pump on the cell membranes or amino acids entering or leaving the cell.
Explain why the size of cells is limited
Small cells are more efficient that large cells. As the cell grows in size, the distance between the surface of the cell and the center of the cell increases and this slows down the transport nutrients, cellular waste, and other molecules and makes it more expensive. It may seem counterintuitive, because larger cells have larger surface area. You want a cell with larger surface area, the larger the surface area the more contact for diffusion to happen. The problem is that when you increase the surface area, the volume of the interior of the cell increases at a higher rate, so the proportion of surface area to unit of volume decreases. That is what makes large cells less efficient, is not because they have more surface area, the problem is that their volume is many times higher than their surface area. Like a dining table to doubles in size, it can sit more people on the surface but everyone will be so much further away from the food placed in the middle of the table. This results because while surface area increases at the square of the radius (r2), the volume of the cell increases at the cube of the radius (r3).B) Despite their larger size, eukaryotic cells are still efficient despite being much larger than prokaryotic cells due to the fact that they have organelles with specialized functions. Eukaryotic cells have a true nucleus, which holds the purpose of secluding DNA related functions. Likewise, they have lysosomes specialized on digestion, ER for lipid metabolism, mitochondria for energy production, etc. Eukaryotes have membrane-bound organelles that are like chambers for specific reactions. These chambers allow increased efficiency allowing multiple reactions to occur at the same time in separate compartments, thus making the eukaryotic cell more efficient than the prokaryotic cell.
Describe the structure of cellular membranes and explain why cell membranes are modeled as a Fluid Mosaic
The cell membrane is commonly referred to as a fluid mosaic because of the various types of molecules that float freely along the phospholipid bilayer. The 'fluid' part depicts how some areas of the membrane can move around freely, if they are not attached to other parts of the cell - in particular the phospholipids, they are not attached to one another and are free to move around the membrane. The phospholipids are simply attracted to each other by their lipophilic and hydrophilic interactions The 'mosaic' part describes the 'patchwork' of proteins, glycoproteins, phospholipids, cholesterol, and carbohydrates that are arranged side by side to create a single outer surface of the phospholipid bilayer.
Apply the Theory of Endosymbiosis to explain the origin of mitochondria and chloroplast
The endosymbiotic theory offers an explanation for the origin of mitochondria and chloroplasts in modern eukaryotic cells. According to the theory of endosymbiosis, mitochondria originated from a free-living oxygen metabolizing bacterium that was engulfed by an ancestral eukaryotic. Instead of getting broken down, the bacterium survived and provided the host cell the ability to perform aerobic respiration, in exchange, the host provided food and protection. Overtime, their interdependence has grown stronger and now neither can survive without the other. Keep in mind that all eukaryotic cells, including plants, descend from that original cell who engulfed an aerobic prokaryote, thus all eukaryotes have mitochondria. Chloroplasts evolved from free-living photosynthetic bacteria that were also engulfed by the host cell but survived, this host cell already had mitochondria. If chloroplast and mitochondria derived from free-living prokaryotic cells, we predict that they should still have some remnants of cellular structures common to all cells, such as DNA, cell membrane and ribosomes. Moreover, since they derived from prokaryotic cells, we predict that those structures should be more similar to those of prokaryotic cells than those of eukaryotic cells. Indeed both, mitochondria and chloroplasts, contain a double membrane - outer and inner. This outer membrane is the remainder of the cell's membrane from endosymbiosis. In addition, both contain their own DNA independent from the nucleus, which is circular like the chromosome of most prokaryotes. Furthermore, they reproduce by themselves independent of the cell cycle in a manner similar to the binary fission of prokaryotes. Lastly, they convert their own energy - while the mitochondria metabolize sugar to produce ATP, chloroplasts employ light energy to produce ATP. Mitochondria and chloroplasts also have their own ribosomes that resemble prokaryotic ribosomes. All of these traits support the theory that the mitochondria and chloroplasts were once independent prokaryotes that evolved into organelles currently utilized with present day eukaryotic cells (Raven, et al, 2016).
Distinguish molecular bonds from weak bonds
Weak bonds include hydrogen bonds and ionic bonds (aqueous), and van der waals interactions formed by attractions between + and - charges. Weak bonds typically link separate molecules, proteins, and covalent bonds together Covalent bonds (H2 (non-polar), O2 (non-polar), H2O (polar)) are molecular bonds (sharing of electrons between two molecules) and are the strongest bonds. Bonds with uneven electro-negativity are polar covalent bonds, bonds with even electronegativity are non-polar covalent bonds. Strong bonds link atoms together to form molecules by sharing electrons
Explain what is denaturation and why it affects protein function
When a protein unfolds and loses shape due to unnatural pH or temperature. A protein is folded to function within a certain environment. If it is placed in conditions outside of it's normal environment it will lose its tertiary shape and would not be able to function in the different environment