Note
Studied by 11 people
AP BIO UNIT 4 REVIEW
VOCAB
G1 phase - cell carries out its metabolic activities
S phase - DNA replication (each chromatid, carrying a DNA molecule, will produce an identical sister chromatid → see replicated chromosome definition
G2 phase - proteins needed for mitosis are produced
G0 phase - cells are in an arrested or “dormant” state
Chromatin - relaxed state of the chromosomes (looks like a ball of string under a microscope)
Chromatid - a chromosome strand that carries one DNA molecule “\” (an unreplicated chromosome)
Replicated chromosome - a chromosome composed of two strands; carries two DNA molecules “X”
Mitosis produces body cells; the body cells (somatic) are genetically identical to each other; 2n → 2n (both daughter cells are diploid)
Diploid (2n) - a cell that has 2 sets of chromosomes (one set contributed by an egg cell and another set contributed by a sperm cell)
Centromere - a middle point in a chromosome; during anaphase, the centromere splits when the sister chromatids separate
Prophase - chromosomes coil into the “X” shape; spindle fibers form; nuclear membrane breaks down and nucleolus disappears
Metaphase - replicated chromosomes line up unpaired in the middle of the center (spindle fibers pull the chromosomes to the center of the cell)
Anaphase - the sister chromatids of a replicated chromosome are pulled apart by the spindle fibers (the spindle fibers connect to the centromere of a replicated chromosome and pull apart the sister chromatids)
Telophase - cell membrane pinches inward, partitioning the cell; new nuclear membranes form around both groups of chromosomes - the end result is two separate nuclei (each containing the same amount and type of genetic information as the original cell’s nucleus)
Review the following terms’ definitions involved in the Control of the Cell Cycle
G1 checkpoint - checks for if cell size is adequate and DNA is undamaged
G2 checkpoint - checks if DNA is undamaged and replicated fully
M checkpoint - during metaphase, checks if chromosomes are properly aligned in the middle of the cell
Cyclin - internal signaling proteins that increase during a specific phase; cyclins bind to their kinases to promote the next phase (G1 → S phase; G2 → M phase)
Steroid vs. Peptide Hormones Review
- steroid hormones - receptors are located within the cell - these hormones are only involved in activating gene expression
- peptide hormones - receptors are embedded within the target cell (receptors are either in the cytoplasm or in the nucleus of a cell)
- can activate gene expression or activate a protein molecule already present in the cell
- signal transduction pathway (pertains only to peptide hormones)
(1st stage - signal = peptide hormone, 2nd stage - transduce = converting inactive protein kinases into activated protein kinases, 3rd stage - cellular responses = 1) last protein activated performs an enzymatic activity or 2) last protein activated will become a transcription factor and activate gene expression)
- once the receptor (protein) is activated by the peptide hormone, the G protein becomes activated → alpha subunit from the G protein then proceeds to activate the enzyme adenylyl cyclase → adenylyl cyclase converts ATP into cAMP (secondary messenger - activate intracellular signaling pathways that amplify the signal (amplify refers to when protein kinases become activated by phosphorylation and then the activated protein kinases continue activating other protein kinases by phosphorylation).
Phosphorylation refers to when an inactive protein kinase receives a phosphate group from ATP and then becomes activated.
Feedback (Positive and Negative)
- both are used by organisms to respond to environmental changes
- homeostasis - maintenance of a constant internal environment (maintaining a target set point such as blood glucose levels, body temperature)
- feedback - a return to the input of a process
- Negative feedback mechanisms - maintain a target set point (or homeostasis) by regulating certain physiological processes (good examples: maintaining body temperature, blood glucose levels)
- Positive feedback mechanisms - amplify (or increase) processes or responses in organisms; a factor moves a process further away from homeostasis; in other words, the input continues to be activated; good examples: a ruptured blood vessel will continue to stimulate platelet production to cover the damaged blood vessel, a woman giving birth continuously secretes oxytocin which causes uterine muscles to contract
Science Skills tested in MCQs & possibly the FRQ
- review error bars (e.g. if error bars overlap, then there’s no statistical significant different; if error bars don’t overlap, then there’s a statistical significant difference between groups)
- Percent Change in Mass (final - initial mass x 100 = ____ %)
Initial mass
- Chi-Square Test - review how to use the equation
- if your chi-square value is < than the critical value, you will not reject the null
- if your chi-square value is > than the critical value, you will reject the null
Degrees of freedom = # of possible categories - 1
FRQ
- Covers Topics 4.6 The Cell Cycle and 4.7 Regulation of the Cell Cycle
- some questions will cover experimental components:
1) independent variable - what is being manipulated/modified?
2) dependent variable - what is being measured/collected?
3) positive control group - a group known to produce results; sometimes it is the group that is in a natural or regular setting
4) negative control group - a group missing one or more essential components needed to produce results
UNIT 1 AND 2
Unit 1
Key Terms
Ions
Ionic bond (e.g. NaCl)
Covalent bond
Polar covalent
Nonpolar covalent
Electronegativity
Water is a polar molecule
Hydrogen bond
Water has a high specific heat (or high-heat capacity) - water resists temperature changes; since water has so many hydrogen bonds that have to be broken, it is difficult to change liquid water to many water vapors
Water has a high heat of vaporization - in order to convert water from a liquid to a gas; some many of water’s hydrogen bonds have to be broken
Water is a solvent (versatile) - can dissolve polar & ionic compounds
Hydrophilic
Hydrophobic
Cohesion
Adhesion
Surface tension - because of the high number of hydrogen bonds, water resists the stretching and breaking of its surface
Key Terms
Monomer
Polymer
Carbohydrates examples & functions
Monosaccharide (e.g. glucose) - know glucose’s molecular structure (the other monosaccharides - you don’t need to know their molecular structure)
Disaccharide (e.g. maltose)
Polysaccharide (e.g. starch and glycogen)
Dehydration synthesis (or condensation reaction) occurs when one or more water molecules are removed from monomers so that they can join together to form a polymer. (An H from one monomer and an OH from another monomer are removed to form water and a polymer as products); to form a triglyceride (which is a fat molecule) or a phospholipid, a glycerol molecule + fatty acids are joined together to form the polymer (or macromolecule)
Hydrolysis occurs when one or more water molecules are added to a polymer to break it down into its monomers.
Functional group types (what organic molecules have each one? Is the group hydrophilic or hydrophobic); you need to know the chemical formula
1)hydroxyl (carbohydrates) -OH
2) phosphate (lipids - phospholipids & all nucleic acids) PO43-
3) carbonyl (carbohydrates - only in monosaccharides)C=O
4) carboxyl (lipids and amino acids - in fatty acid monomer and amino acid monomer) COOH
5) methyl (lipids only - only one that is hydrophobic) CH3
6) amino (proteins only - it is hydrophilic) NH2
Lipids
Fatty acid (saturated vs. unsaturated) - know their molecular structures - remember that saturated fatty acids only have single bonds between carbon atoms, whereas unsaturated have one or more double bonds between carbon atoms
Glycerol (added to fatty acids to make a triglyceride or phospholipid); know the molecular structure
Triglyceride - polymer of a lipid - know molecular structure
Phospholipid - polymer of a lipid - know molecular structure
Nucleic Acids
DNA and RNA - be familiar with the chart comparing DNA & RNA in daily video; you are going to have to memorize/know the 5’ → 3’ characteristics of DNA & RNA
Monomer - Nucleotide (phosphate group, sugar group, & nitrogen base)
Sugar group - deoxyribose or ribose
Nitrogen bases - DNA contains adenine, guanine, cytosine, and thymine); RNA contains adenine, guanine, cytosine, and uracil (you don’t need to remember their molecular structure, but you need to know which ones are found in DNA and RNA)
Pyrimidines - are nitrogen bases that have one ring with nitrogen atoms in them (examples are thymine, cytosine, and uracil)
Purines - are nitrogen bases that have two rings with nitrogen atoms in them (examples are adenine and guanine)
Nucleoside - consists of a sugar group & nitrogen base
Nucleotide - consists of a sugar group, nitrogen base and one or more phosphate groups.
An example of a nucleotide is ATP (adenosine triphosphate) - it is an RNA nucleotide - serves as an energy carrying molecule (or energy currency) for cells so that they can do work.
Proteins
Amino acids - the building blocks (or monomers) of proteins
There are 20 different types of amino acids - they all differ in the R (side chain) group
Primary level of protein structure - straight chain of amino acids connected by peptide bonds forms a polypeptide chain; peptide bond occurs between the carboxyl end of one amino acid and the amino group of another amino acid
Secondary level of protein structure - polypeptide chain folds into either a Beta-pleated sheet or alpha-helix - the folding is caused by hydrogen bonds between amino acids (specifically between the oxygen atom at the carboxyl end of one amino acid and the hydrogen end at the amino end of one amino acid)
Tertiary level of protein structure - polypeptide chain continues folding into a shape - what causes the folding at this level are different types of bonding at the R groups - types of bonding that can happen - hydrogen bonding, disulfide bridges, ionic bonding, and hydrophobic interactions
Quaternary level of protein structure - forms the final protein; occurs when 2 or more polypeptide chains come together; there can be a hydrogen, hydrophobic, or ionic bond that will join the polypeptide chains together
Unit 2
Topic 2.4 Plasma Membrane
- membrane is mostly composed of phospholipids; phospholipids are amphipathic (one region is hydrophilic (polar head) and the other region is nonpolar (fatty acid tails)
- Cholesterol - regulates the movement of the phospholipid tails -
- in animal cells, if temperature is high, cholesterol reduces the speed of saturated fatty acid tails moving since cholesterol is wedged in between the phospholipids
- in animal cells, if temperature is low, cholesterol maintain the speed of saturated fatty acid tails from compacting/compressing
- the membrane is a fluid-mosaic; fluid refers to the movement of fatty-acid tails of phospholipids; mosaic refers to the membrane having a variety of proteins that serve different functions
- Examples of proteins that makeup a membrane:
Receptor proteins - these are peripheral proteins that are activated by specific chemical signals or hormones
Enzyme - these are also peripheral or integral proteins that catalyze chemical reactions at the membrane
Glycoproteins - these are proteins that have certain carbohydrates attached to them; these function in cell-to-cell recognition
Transport proteins - these are integral proteins that transport large, polar molecules (e.g. glucose, amino acids) and ions across the membrane; there are 2 types: carrier proteins and channel proteins
Topic 2.5 Membrane Permeability
- Membrane permeability is due to membrane structure, specifically due to the phospholipids and the transport proteins
- Nonpolar molecules (e.g. small lipids and gaseous molecules) and small polar molecules (e.g. water) can diffuse across the membrane in between the phospholipids; large polar molecules (such as glucose and amino acids) and ions cannot simply diffuse across the membrane in between the phospholipids, so they must have transport proteins such as channel proteins or carrier proteins
- plasmodesmata - are holes within cell walls of adjacent plant cells that allow the movement of water carrying molecules from one cell to another
Topic 2.6 Membrane Transport
- Concentration gradient occurs when there is a higher amount of a substance on one side of a membrane; a membrane creates the concentration gradient
- Passive transport is the movement of molecules or ions down their concentration gradient; energy is not needed
2 Types of Passive Transport:
Diffusion - occurs when nonpolar molecules and small polar molecules to diffuse directly across the membrane; Osmosis refers to the diffusion of water across a membrane
Facilitated Diffusion - occurs when large polar molecules, ions, and water travel across the membrane by using a transport protein.
- Active transport is the movement of a substance against its concentration gradient; energy (ATP) is
needed to change the carrier protein’s shape so that the protein can carry out active transport
Turn to the next page→
- Endocytosis is the transport of bulk material (e.g. proteins, polysaccharides, lipids, or even organisms) into a cell; the cell membrane will “wrap” around the substances and the substances will be brought into the cell enclosed within a vesicle
3 types of Endocytosis:
Phagocytosis - the uptake of large particles into the cell
Pinocytosis - the uptake of fluid into a cell
Receptor-mediated endocytosis - specific molecules, e.g. cholesterol (also known as LDL - low-density lipoproteins), attach to receptors found on the outside surface of the membrane and be taken into the cell; people who have a genetic disorder where they lack these receptors for taking in cholesterol result in having high cholesterol in their blood - the genetic disorder is called familial hypercholesterolemia
- Exocytosis is the transport of substances such as wastes or hormones out of the cell.
Graphing Review - Topic 2.8 Video #2
- independent variable - the variable being manipulated - goes on the x-axis
- dependent variable - the variable you are measuring - goes on the y-axis
- The following acronym can be used in constructing a graph - TAILS - Title, Axes labeled, Intervals are Equal, Labeled Lines/Bars, and Scale is Appropriate)
Study the notes that were handed out over Photosynthesis and AP Classroom Daily Videos 2.8 and 3.5
Topic 2.8 Tonicity and OsmoregulationWater Potential Calculations:
Water Potential = solute potential + pressure potential
Ѱ = Ѱs + Ѱp
Solute potential (Ѱs = -icRT)
Key points about water potential:
*Water potential measures the tendency of water to move from a high water potential area to a low water potential area (example: water always moves towards the lower or more negative water potential environment)
*An increase in solute concentration lowers the solute potential (in other words, the increase in solute concentration makes the solute potential more negative).
*All types of sugar molecules have an ionization constant of 1 since sugar is still 1 ion when it dissolves in water; NaCl has an ionization constant of 2 (since NaCl breaks up into 2 ions when it dissolves in water)
*At equilibrium, the cell and its outer environment have the same water potential value (the value can be negative or positive for both of them)
*An increase in solute concentration lowers the solute potential
Hypertonic - refers to an environment that has a greater amount of solute concentration relative to another environment; a plant cell placed in a hypertonic environment will plasmolyze (shrink)
Hypotonic - refers to an environment that has a lower amount of solute concentration relative to another environment; a plant cell placed in a hypotonic environment will become turgid (swell)
Isotonic - refers to an environment that has the same amount of solute concentration relative to another environment; a plant cell in an isotonic environment is flaccid
There will be questions on the test from the Osmosis in Plant Cells Lab - so make sure you review the lab. This is the lab where we placed potato cores in different concentrations of sucrose. We used the percent change in mass in determining the solute concentration and solute potential of the potato cores.
Calculate %change in mass = ( Final value - Initial value) x 100
Initial Value