AP Bio Unit 3: Cellular Energetics

anabolic reactions

forming bonds between molecules consuming energy to build complicated molecules from simpler ones

catabolic reactions

breaking bonds between molecules; breakdown pathways; like digestion(hydrolysis)

exergonic reactions

chemical reactions that release energy

endergonic reactions

chemical reactions that require input of energy

activation energy

the energy required to break bonds in the reactant molecules and start chemical reactions; must absorb energy to break bonds

Enzyme

a protein that reduces the activation energy of reactions in a cell, but is not used up in the reactions (acts as a catalyst) - speeds up a reaction

enzyme specificity

enzymes have a specific shape to specific chemical reaction (1 enzyme = 1 reaction type)

substrate

substance on which the enzyme acts; binds to enzyme according to shape

active site

enzymes catalytic site; substrate fits like a key into a lock

Denaturation

Destroying the function of a protein by changing its structure (can be done by changing temperature, pH, or salinity)

Induced Fit model

substrate binding causes enzyme to change shape and have tighter fit

Increasing Enzyme Concentration

more enzymes equals more frequently collide with substrate; equilibrium is reached when the amount of substrate equals the amount of enzyme

Increasing substrate concentration

More substrate equals more frequent collisions with enzymes; all enzymes have active site engaged; enzyme becomes saturated

inhibitors

molecules that reduce enzyme activity

competitive inhibtion

inhibitor competes with substrate for active site by binding in the active site and blocking the substrate

non-competitive inhibition

type of inhibition where an inhibitor binds to site other than active site causing enzyme to change shape; active site no longer functions

Allosteric regulation

when molecules bind somewhere other than the active site; cause a change in enzymes shape; can inhibit or activate

Feedback inhibition

the final product is in a metabolic pathway is an enzyme inhibitor for an earlier step

Cofactors

small inorganic compounds like Mg, K, Ca, Zn and other minerals; that increase the activity of enzymes

Coenzymes

non-protein organic molecules that bind temporarily or permanently to enzyme near active site; like many vitamins

Allosteric Inhibitor

a molecule that binds to allosteric site and reduces enzyme activity

Allosteric activator

a molecule that binds to allosteric site and increases enzyme activity

Enzyme cooperativity

A substrate molecule bound to an active site of one subunit promotes substrate binding to the active site of other subunits.

Metabolism

All of the chemical reactions that occur within an organism

Entropy

A measure of disorder or randomness.

energy coupling

The use of an exergonic process to drive an endergonic one.

Autotroph

An organism that makes its own food

Heterotroph

organism that obtains energy from the foods it consumes; also called a consumer

Oxidation

loss of electrons (or hydrogen)

reduction

gain of electrons (or hydrogen)

Phosphorylation

the addition of a phosphate group to a molecule

Chemiosmosis

making ATP using the energy from a hydrogen ion concentration gradient and the ATP synthase enzyme.

ATP synthase

The enzyme that makes ATP from ADP and inorganic phosphate.

reactants of cellular respiration

glucose and oxygen

reactants of photosynthesis

carbon dioxide and water

products of cellular respiration

carbon dioxide, water, and ATP

products of photosynthesis

glucose and oxygen (products)

Glycolysis

breakdown of glucose into pyruvate; produces small amount of ATP; no oxygen required

location of glycolysis

cytoplasm

location of citric acid cycle

matrix of mitochondria

products of the citric acid cycle

NADH, FADH2, CO2, some ATP

location of electron transport chain

inner mitochondrial membrane (cristae)

cellular respiration electron carriers

NAD+/NADH and FAD/FADH2

photosynthesis electron carriers

NADP+ to NADPH

Products of cell respiration Electron Transport Chain

water and lots of ATP

final electron acceptor in cell respiration

Oxygen

Fermentation

Process by which cells release energy in the absence of oxygen

products of fermentation

ethanol and lactic acid

inputs of light reactions

light, water, ADP, NADP+

products of light reactions

ATP, NADPH, O2

location of light reactions

thylakoid membrane

location of Calvin cycle

stroma

Inputs of Calvin Cycle

CO2, ATP, NADPH

Main Product of Calvin Cycle

G3P (used to make sugars like glucose)

CAM plants

plants close their stomata during the day, collect CO2 at night, and store the CO2 in the form of acids until it is needed during the day for photosynthesis

ATP production in both cell respiration and photosynthesis

electron transport chain and chemiosmosis

C4 plants

separate the reactions in photosynthesis by running the light reactions and the Calvin Cycle in different cells

C4 and CAM plants

plants that have adapted to hot, dry conditions

Role of pigments in photosynthesis

absorb light energy at specific wavelengths