AP Biology Unit 3

enzyme

biological catalyst proteins that speeds up a chemical reaction by lowering activation energies; must have tertiary structure maintained

active site

substrate-specific (physically and chemically) area on an enzyme that binds the substrate and facilitates the reaction.

activation energy

biological energy required for a reaction to occur

denaturation

change in an enzyme’s tertiary structure due to temperature or pH changes; usually irreversible lost or severely limited catalytic ability

temperature increases

initially increase reaction rate but denatures the enzyme past the optimum range

temperature decreases

slows reaction rate but does not disrupt enzyme structure

change in pH

disrupt hydrogen bond interactions that maintain enzyme structure

competitive inhibitors

bind reversibly or irreversibly to the enzyme’s active site, blocking the normal substrate

noncompetitive inhibitors

bind to the allosteric site on an enzyme, causing structural change to the enzyme that makes it no longer available to the normal substrate

allosteric site

a specific region on an enzyme where regulatory molecules bind, resulting in changes to enzyme activity

metabolism

the sum of all chemical reactions that occur in a cell

free energy

the amount of energy available after a reaction has occurred

exergonic

energy is released

endergonic

energy input is required

adenosine triphosphate

nucleotide composed of adenine, ribose, 3 phosphates; does chemical, transport, and mechanical work

metabolic pathways

series of linked reactions that are highly structured and organized to conserve energy

energy coupling

energy-releasing processes power energy-storing processes

sequential pathways

one reaction’s product(s) can be used as reactant in a subsequent reaction; increases control and efficiency

photosynthesis

biological process that captures energy from the sun and produces sugars

light-dependent reactions

capture light energy with chlorophylls, store it as chemical energy in NADPH bonds, and generate ATP through photophosphorylation

chlorophylls

capture energy from sunlight and convert it to high-energy electrons to establish a proton gradient and reduce NADP+

photosystems I and II

light-capturing units in thylakoids membrane; these pass high-energy electrons to the electron transport chain

Calvin cycle

uses ATP, NADPH, and CO2 to produce carbohydrates; steps: carbon fixation, reduction, RuBP regeneration

cellular respiration

series of enzyme-catalyzed reactions to capture energy from biological molecules to produce ATP

glycolysis

occurs in the cytoplasm; produces pyruvate, NADH, and ATP from glucose and NAD+

link reaction

occurs in the mitochondrial matrix; produces acetyl-coA, NADH, and CO2 from pyruvate and NAD+

Krebs cycle

occurs in the mitochondrial matrix; produces CO2, NADH, FADH2 and ATP from acetyl-coA, NAD+, Fad, and ADP

oxidative phosphorylation

occurs in the inner mitochondrial membrane; produces ATP and water from NADH, FADH2, and oxygen

chemiosmosis

movement of ions (specifically protons) across a semipermeable membrane down their electrochemical gradient to produce ATP

decoupling

energy stored in proton gradient is released as heat; this process can be used by endotherms to regulate their body temperature

fermentation

a metabolic process that converts sugar to acids, gases, or alcohol in the absence of oxygen, allowing for ATP production without aerobic respiration; produces ethanol or lactic acid

ATP phosphate removal

releases energy by breaking a covalent P-P bond

coenzyme

an organic non-protein molecule that assists enzymes in catalyzing reactions; required for enzymatic activity

cofactor

an inorganic, non-protein chemical compound; bind allosterically

light reaction inputs

in: light, NADP+, ADP, H2O

light reaction outputs

out: oxygen, NADPH, ATP

Calvin cycle inputs

in: CO2, ATP, NADPH

Calvin cycle outputs

out: glucose, ADP, NADP+

aerobic respiration

3 steps, OXYGEN required as final electron acceptor in ETC; produces up to 38 ATP from 1 molecule of glucose

anaerobic cellular respiration

similar to aerobic cellular respiration; uses a non-oxygen final electron acceptor (ex. nitrate, sulfur, others)

fermentation

partial sugar breakdown that occurs without oxygen; occurs in cytosol and is only glycolysis with ethanol or lactic acid as waste

glycolysis inputs

in: glucose, NAD+, and ATP

glycolysis outputs

out: pyruvate, NADH, ATP, water

link reaction inputs

in: pyruvate, NAD+

link reaction outputs

out: acetyl CoA, NADH, carbon dioxide

Krebs cycle inputs

in: acetyl CoA, NAD+, FAD, ADP

Krebs cycle outputs

out: ATP, NADH, FADH2, carbon dioxide

oxidative phosphorylation inputs

in: NADH, FADH2, oxygen, ADP

oxidative phosphorylation outputs

out: ATP, NAD+, FAD, water

first law of thermodynamics

energy cannot be created or destroyed; only changed from one form to another

second law of thermodynamics

energy can’t be changed from one form to another without a loss of useable energy (often heat)