BIO: Unit 3 EXAM

energy

the ability to promote change or do work

kinetic energy

energy associated with movement

potential energy

energy stored because of an object’s structure or location

endergonic reactions

require an input of energy, have a ΔG, associated with anabolism (building molecules)

chemical potential energy

energy stored in molecular bonds, such as those in glucose and triglycerides

metabolism

all chemical reactions that occur in cells

exergonic reactions

release free energy, have a -ΔG, associated with catabolism (breaking down molecules)

Entropy

the degree of disorder in a system

First Law of Thermodynamics

energy cannot be created or destroyed; can only be transformed

Second Law of Thermodynamics

Energy transfers increase entropy

ATP hydrolysis

Breaks off an outer phosphate group, forming ADP and inorganic phosphate and releasing free energy.

catalyst

speeds up a chemical reaction without being consumed

Oxidation

Loss of electrons.

Energetic coupling

Uses energy released by an exergonic reaction to drive an endergonic reaction.

Redox reactions

Reactions involving electron transfer.

Free energy

Energy available to do work.

Enzyme

A protein catalyst in living cells

Active site

The location on an enzyme where the substrate binds

Ribozyme

An RNA molecule with catalytic properties

Substrate

The molecule an enzyme acts on

Reduction

Gain of electrons

Transition state

A high-energy intermediate state that reactants must reach for a reaction to proceed.

Activation energy

The energy needed to reach the transition state

Substrate concentration

Reaction speed increases as substrate concentration rises, until the enzyme reaches its maximum speed.

Saturation

Nearly all active sites are occupied by substrates.

Positive Feedback

The product stimulates more production of itself.

Substrate binds to the enzyme (active site), Induced fit occurs, reaction occurs, products are released

How enzymes work.

Affinity

The degree of attraction between an enzyme and its substrate.

Negative Feedback

The product slows/inhibits further production.

Competitive inhibition

An inhibitor binds to the active site and competes with the substrate.

Michaelis constant

The substrate concentration at which reaction velocity is half its maximum value.

Anabolic pathways

Build or synthesize cellular components, are endergonic, require energy, often supplied by coupling to exergonic reactions.

Allosteric activation

A regulatory molecule binds at another site and changes the enzyme's shape to make the active site available.

Noncompetitive inhibition

An inhibitor binds at an allosteric site and lowers the reaction's maximum velocity without affecting

Biochemical Regulation

controls reactions through mechanisms such as feedback inhibition

Allosteric inhibition

A regulatory molecule binds at another site and changes the enzyme's shape so the active site becomes unavailable.

Catabolic pathways

Break down cellular components, are exergonic, release energy.

Rate- limiting step

The slowest step in a pathway; changing it has a major effect on the pathway's overall rate