AP Biology Midterm Study Guide

Polarity

Uneven distribution of electrical charge within a molecule

Hydrogen bond

weak attraction between a partially positive hydrogen and a partially negative atom (like oxygen)

Cohesion

Attraction between molecules of the same substance (water sticking to water)

Adhesion

Attraction between molecules of different substances

Specific heat

Amount of energy required to change a substance's temperature

Heat of vaporization

Energy needed to change liquid water to gas

Why water is polar

Oxygen is more electronegative than hydrogen, pulling electrons closer

Polar molecule

Molecule with uneven charge that dissolves in water

Nonpolar molecule

Molecule with even charge that does not dissolve in water

Hydrophilic

Water-loving; attracted to water

Hydrophobic

Water-fearing; repelled by water

Cis isomer

Functional groups on the same side of a double bond (kinked)

Trans isomer

Functional groups on opposite sides of a double bond (straighter)

Carbohydrates

Macromolecules made of C, H, and O in a 1:2:1 ratio; used for energy and structure

Lipids

Nonpolar macromolecules used for long-term energy, membranes, and hormones

Proteins

Macromolecules made of amino acids; perform most cell functions

Primary protein structure

Sequence of amino acids

Secondary protein structure

Alpha helices and beta sheets formed by hydrogen bonds

Tertiary protein structure

Overall 3D shape from R-group interactions

Quaternary protein structure

Multiple polypeptide chains joined together

Nucleic acids

DNA and RNA; store and transmit genetic information

Glucose

Monosaccharide and primary energy source for cells

Amino acid

Monomer of proteins with amino group, carboxyl group, R group, and central carbon

Dehydration synthesis

Builds polymers by removing water

Hydrolysis

Breaks polymers by adding water

Starch

Storage polysaccharide made of alpha-glucose

Cellulose

Structural polysaccharide made of beta-glucose

Effect of amino acid change

Can alter protein folding and function

Prokaryote

Cell without nucleus or membrane-bound organelles

Eukaryote

Cell with nucleus and membrane-bound organelles

Endosymbiotic theory

Mitochondria and chloroplasts evolved from free-living bacteria

Mitochondria

Site of cellular respiration and ATP production

Plasma membrane

Selectively permeable barrier controlling cell entry and exit

Golgi apparatus

Modifies, sorts, and ships proteins

Rough ER

Protein synthesis (ribosomes attached)

Smooth ER

Lipid synthesis and detoxification

Lysosome

Digests waste and old organelles

Nucleus

Stores DNA and controls cell activities

Ribosome

Site of protein synthesis

Surface area-to-volume ratio

Determines efficiency of material exchange

Phospholipid bilayer

Double layer with hydrophilic heads and hydrophobic tails

Passive transport

Movement across membrane without energy

Active transport

Movement against concentration gradient using energy

Diffusion

Movement from high to low concentration

Facilitated diffusion

Passive transport using proteins

Osmosis

Diffusion of water across a membrane

Water potential

Potential energy of water; highest in pure water

Solute potential

Effect of dissolved solutes on water movement

Aquaporins

Channel proteins that transport water

Pigments

Molecules that absorb light energy

Chlorophyll

Primary photosynthetic pigment absorbing blue and red light

Light-dependent reactions

Convert light energy to ATP and NADPH

Calvin cycle

Uses CO₂, ATP, and NADPH to produce glucose

Glycolysis

Breaks glucose into pyruvate in cytoplasm

Krebs cycle

Produces electron carriers in mitochondrial matrix

Electron transport chain

Produces most ATP using electrons and proton gradient

ATP

Main energy currency of the cell

NADH/FADH₂

Electron carriers

ETC disruption

Decreases ATP production

Enzyme

Protein that lowers activation energy

Denaturation

Loss of enzyme shape due to extreme temperature or pH

Ligand

Signaling molecule that binds to a receptor

Reception

Ligand binds receptor

Transduction

Signal relay inside cell

Response

Cellular action taken

Phosphorylation cascade

Series of protein activations via phosphate groups

Extracellular receptor

Receptor on cell surface

Intracellular receptor

Receptor inside cell

Cell cycle

Life cycle of a cell

G1 phase

Cell growth

S phase

DNA replication

G2 phase

Preparation for mitosis

Mitosis

Division of nucleus

Prophase

Chromosomes condense

Metaphase

Chromosomes line up

Anaphase

Sister chromatids separate

Telophase

Nuclear membranes reform

Cytokinesis

Cytoplasm divides

Cyclins

Proteins that regulate cell cycle timing

CDKs

Enzymes activated by cyclins

Checkpoint

Control point in cell cycle

Apoptosis

Programmed cell death

Negative feedback

Reverses a change

Positive feedback

Amplifies a change

FRQ-Specific Terms

Null hypothesis

Statement that there is no effect or difference

Competitive inhibitor

Competes with substrate for active site

Noncompetitive inhibitor

Alters enzyme shape

Facilitated diffusion graph

Rate increases then plateaus

Aquaporin function

Speeds up osmosis