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AP Bio - 1st Sem Final

Terms in this set (62)

how do the unique chemical and physical properties of water make life on earth possible?
Water is often nicknamed the "universal solvent" as it can dissolve other substances. Those which dissolve well are hydrophilic (eg. salts, sugars, acids), whereas those which do not are called hydrophobic (eg. fats, oils). Water has a high specific heat (the amount of energy needed to raise the temperature of 1 gram 1 degree Celsius) and a high heat of vaporization (the energy needed to turn a liquid into a gas) due to the many hydrogen bonds and then breaking the hydrogen bonds. The high specific heat allows water to keep the Earth's climate moderate, protecting us from any huge changes in temperature. The high heat of vaporization is important in humans when they sweat. The change from a liquid to a gas is what creates the cooling sensation. A high surface tension exists with water. Due to cohesion, water molecules have hydrogen bonds which attract to one another. This is important in transpiration, as the water molecules stick to each other as they move up a tree.
what is the role of carbon in the diversity of life?
Carbon is a key player in biochemistry because it can form four stable bonds to other atoms at once. This means it can form long chains and also bind reactive side groups that help it bend into useful shapes and elaborate structures. It is thought that if life develops on other planets it would probably have to be carbon-based or silicone-based because they are the only elements that can form such chains.
how do cells synthesize and break down macromolecules?
Two monosaccharides, such as glucose and fructose, are hooked together by a process called dehydration synthesis. A larger molecule is synthesized by removing a water molecule from between them - an H from one and an OH from the other, freeing up a covalent bond on each. Two of those free bonds join together to make HOH (water), and the other 2 join to make the disaccharide called sucrose
how do structures of biological molecules account for their function (carbs, proteins, lipids, DNA)?
Carbohydrates- different types
- monosaccharides (glucose and company)
- disaccharides (maltose and sucrose, etc.)
- polysaccharide (starch and multiple monosaccharides bonded together)
These carbohydrates as used to make ATP via cellular respiration. It's basically a place for energy storage. It can also be used in cells as cell walls (chitin and cellulose are both carbohydrates). Their structure is appropriate, because it's purpose is an energy bank and thus getting the energy when it is needed would be helpful. All you have to do to get energy from polysaccharides is just add H2O and it'll become a simpler monosaccharide, easily able to be formed into ATP.

Lipids- Includes triglycerides, steroids, phospholipids, and fats.
Fats: fatty acids and glycerol, has a carboxyl group at the end. Fats help to protect organs, provide insulation, and to store energy.
Saturated and Unsaturated Fats: Saturated has kinks, Unsaturated has no kinks.

Phospholipids: Has a hydrophobic and hydrophilic part. Vital to the fluid mosaic membrane model. It's structure keeps it so there are hydrophilic parts facing the water while the hydrophobic parts do not in the cell membrane.
Steroids: Hormones and stuff are included in this.
Triglycerols: make up body fat, good for storage of energy.

Proteins- Many different types and functions of proteins, including but not limited to:
- Structural proteins
- Storage proteins
- Transport proteins
- Enzymes
Primary structure is composed of amino acids; secondary structure are alpha helixes and beta sheets; Tertiary structure are folds of a-helixes and b-sheets, R group interactions make them fold; Quaternary structure have complex folds and twists, interaction between proteins with subunits.

Nucleic acids- Usually found in DNA/RNA, have genetic info stored in chains of nucleotides. Nucleotides: Adenine, Guanine, Cytosine, Thymine
what are the similarities and differences between prokaryotic and eukaryotic cells?
Prokaryotic cells:
· Less complex
· DNA is located in the nucleoid which is not membrane bound
Chromosomes are dispersed in the cytoplasm
No true nucleus and no membrane-bound organelles
Have circular chromosomes and lack histone proteins
Small - typically 0.1-1.0 micrometers in diameter
Have a primitive cytoskeletal structures or don't have a cytoskeleton at all
Reproduce sexually by the transfer of DNA fragments through conjugation. Don't undergo meiosis.


Eukaryotic cells:
More complex
DNA is located in the nucleus, bonded by a double membrane
Contain true nuclei in which chromosomes are compacted as chromatin
Contain membrane-bound organelles
Have linear DNA and contain histone proteins
Larger - typically 10-100 micrometers in diameter
Have a complex cytoskeleton
Reproduce sexually with the use of meiosis
what is the evolutionary relationships between prokaryotic and eukaryotic cells?
Eukaryotes are the cells that make up our bodies, plants and animals and all cellular organisms that contain their genetic material in a nucleus, have a cytoskeleton and contain organelles, such as mitochondria or cytoplasts. Eukaryotes are thought to have evolved from prokaryotes. Bacteria and archaea are classified as prokaryotes, a group of simple, single-cell organisms. Prokaryotes usually contain a single, circular deoxyribonucleic acid, DNA, molecule and lack a nucleus and intracellular organelles.
how does compartmentalization organize a cell's functions?
Compartmentalization allows each compartment to perform specific functions without interference from other cell functions. For example, lysosomes can break down cell debris in a compartment without accidentally digesting the cell itself.

It also allow enzymes and substrates to reach higher concentrations than if everything was diluted by the entire cytoplasm. For example, the mitochondria accumulates a large electron gradient in order for the electron transport chain to work.
how are the structures of the various subcellular organelles related to their functions?
They are directly related to their functions. The mitochondrial cristae have a higher surface area to facilitate cellular respiration. The phospholipid bilayer of a cell membrane allows nutrients and fat soluble vitamins across the cell membrane. Cilia and flagella function as propellers for locomotion. The rigid cell wall of plants provides structure.

In each of the above cases, structure influences function. Cells have evolved over time to efficiently carry out their respective functions.
how do organelles function together in cellular processes?
Organelles such as the cell wall and membrane work with the rest of the cell by not letting in/out certain particles, and providing structural integrity. The nucleus works with the nucleolus by creating to make ribosomes, which are then transported to the rough endoplasmic reticulum. Proteins are then made. Proteins travel through channels in the endoplasmic reticulum and go to the golgi body. The golgi body packs and makes them ready to be transported to the border of the cell.


The nucleus is the organelle that functions as the command center. The nucleus contains the genetic code material, in the form of DNA, that coordinates the growth and function of the rest of the cell.An organelle that works very closely with the nucleus is the ribosome. The ribosome---through the molecule messenger RNA---obtains the codes from the DNA in the nucleus for building cellular proteins.A fairly large and extensive organelle is the endoplasmic reticulum. The endoplasmic reticulum is a complex series of folded membranes. It is connected to the membrane that surrounds the nucleus and extends out into the cell's cytoplasm. In doing so, it establishes a chemical communication pathway between the nucleus and the cytoplasm. One of its critical functions is to transport proteins within the cell. An organelle that is somewhat similar to the endoplasmic reticulum is the Golgi apparatus. It functions in a similar way except that it specializes in preparing materials, like proteins, for transport through the cell membrane to the exterior of the cell.
what is the current model of molecular architecture of membranes?
The fluid mosaic model concept was introduced by Singer and Nicholson. The name arose because they believed there was a phospholipid bilayer where membrane proteins were able to move, rather than be static. The membrane mainly consists of lipids with hydrophobic tails and hydrophilic heads. Within this layer, there are many different proteins. These include integral membrane proteins, which are partially inserted and peripheral proteins which attach to the surface. There also is cholesterol imbedded and carbohydrates on the outer portion, used as markers. The membrane is selectively permeable, as it allows some small molecules to pass through, but keeps others out unless there are certain types of transport proteins which go through the membrane.
how do variations in this structure account for functional differences among membranes?
Membranes are made up of scattered proteins embedded in/associated with the phospholipid bilayer. but these scattered proteins are not incorporated into the membrane at random. there are different proteins with different structures, and therefore different functions that are embedded in different membranes. in the cell membrane, there are embedded proteins that function in transporting nutrients into the cell, and waste products out of the cell. in the membranes of your mitochondria, proteins are needed to serve as electron carriers (this makes the electron transport chain work). orientation of proteins in the membranes is important because when your mitochondria creates a proton gradient, all the protons must flow in the same direction. the ATP synthase protein directs this proton flow. if the ATP synthase were oriented backwards in the membrane or on a different cell, the protons would flow backwards or not at all and that would suck then we wouldn't be able to create energy.
how does the structure of membranes provide for transport and recognition?
The fluidity of membranes
Membranes are held together by hydrophobic interactions
Proteins and lipids can move around laterally on one layer but rarely flip to the other side
Some move along the cytoskeleton fibers
Membrane remains fluid as temperature decreases until the phospholipids settle into a closely packed arrangement
Membrane remains fluid longer if there are more phospholipids with unsaturated hydrocarbon tails
Separated more because of the kinks in the tails
Cholesterol
At higher temperatures, it makes the membrane less fluid
Restrains phospholipid movement
Lowers the temperature required for membranes to solidify because they are packed less tightly
Temperature buffer


Major functions of proteins in the plasma membrane


Transport
Hydrophilic channel through the protein
Shuttle a substance from one side to the other by changing shape
Enzymatic Activity
May have an active site exposed to substances in the adjacent solution
Signal Transduction
May have a binding site with a specific shape that fits the shape of a chemical messenger, such as a hormone
May cause a shape change in the protein that relays the message to the inside of the cell
Cell-Cell Recognition
Some glycoproteins are identification tags that are recognized by membrane proteins of other cells
Intercellular Joining
Membrane proteins of adjacent cells may hook together in junctions
Attachment to the Cytoskeleton and Extracellular Matrix
Microfilaments may be bound to membrane proteins, which stabilizes the location of certain membrane proteins and maintain cell shape
what are various mechanisms by which substances can cross the membrane?
Diffusion: moves from high to low concentration; no energy required

Osmosis: the movement of water through a membrane until reaching equilibrium. There are three different types of osmotic conditions. Hypertonic is the movement of water out of the cell. Hypotonic is the movement of water inside the cell in which the cell becomes turgid. The third type of osmosis is isotonic in which equal amounts of water move in and out of the cell.

Facilitated Diffusion: carrier proteins aid in moving the substrate through the membrane if the substance cannot diffuse directly through the membrane itself; continues, to move from high to low concentration; no energy required


Active Transport: Energy is required as it is going against the concentration gradient. Proteins can be uniports (moving a single type of solute in one direction), symports (two types of solutes moving in the same direction), or antiports (two different molecules in two different direction). Usually, symports and antiports are seen together.
in osmosis and diffusion lab, how was osmosis measure in both living and artificial?
Overview: Various size cubes of phenolphthalein agar were placed in NaOH and then diffusion rates were calculated.
IV- Size of cube
DV- percent diffusion
what was the IV in the dialysis bag part of the lab? DV? control? controlled variables?
Overview: Students were provided with dialysis bags, colored sucrose solutions of unknown molarities, and basic lab equipment to use to design an experiment on how to determine the molarities of the colored solutions.
IV- unknown molarities
DV- for most groups it was percent change in mass
Control-
CV-
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