Energy & Enzymes (AP Bio Topics 3.1-3.4)

metabolism

The sum of the building & breaking reactions occurring in cells

catabolic pathways

Series of reactions that release energy by breaking down complex molecules into simpler compounds; Negative ΔG

anabolic pathways

Series of reactions that consume energy to build complicated molecules from simpler ones; Positive ΔG

kinetic energy

Energy associated with relative motion of objects.

thermal energy

Kinetic energy associated with the random movement of molecules or atoms. (heat)

potential energy

Stored energy.

entropy

A measure of disorder or randomness. Tends to increase in the universe.

free energy

Measures the portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell.

endergonic reaction

Reaction that absorbs free energy from its surroundings.

exergonic reaction

Reaction that proceeds with a net release of free energy.

energy coupling

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

ATP (adenosine triphosphate)

Composed of a sugar ribose, nitrogenous base adenine, and a chain of three phosphate groups bonded to it.

phosphorylation

The metabolic process of introducing a phosphate group into an organic molecule.

catalyst

A chemical agent that speeds up a reaction without being consumed by the reaction.

enzyme

Protein that speeds up reactions. Typically end in "ase" (ex. Peroxidase, Lipase)

activation energy

The amount of energy needed to push the reactants over an energy barrier.

enzyme-substrate complex

When an enzyme binds to its substrate, it forms:

active site

A pocket or groove on the surface of the enzyme where a substrate can bind.

induced fit model

States that the enzyme and substrate undergo conformational changes to interact fully with one another (as opposed to "Lock & Key"

competitive inhibitors

Reduce the productivity of enzymes by blocking substrates from entering active sites.

noncompetitive inhibitors

Impede enzymatic reactions by binding to another part of the enzyme (other than the active site).

feedback inhibition/negative feedback

A metabolic pathway is switched off by the inhibitory binding of its end product to an enzyme that acts early in the pathway.

saturated enzyme

Describes an enzyme's maximum activity when every active site is being used.

Chemical Energy

Potential energy trapped in molecular bonds.

Spontaneous Reaction

When a reaction doesn't require energy to proceed it is said to be this - doesn't mean it will be FAST.

chemical reaction

A process that changes one set of chemicals into another set of chemicals.

reactants

compounds that enter into a chemical reaction

product

compounds produced by a chemical reaction.

Competitive inhibition

substance that resembles the normal substrate competes with the substrate for the active site

Noncompetitive inhibitor

a chemical that binds to an enzyme but not in the active site. This chemical will change the shape of the enzyme (reversible)

substrate

A specific reactant acted upon by an enzyme

exothermic reaction

a chemical reaction where energy is given off, so that the products have less energy than the reactants.

endothermic reaction

a chemical reaction where energy is taken in, so that the products have more energy than the reactants.

Denature

A change in the shape of a protein (such as an enzyme) that can be caused by changes in temperature or pH (among other things).

Allosteric

__________ regulation of enzyme occurs when a molecule binds to an enzyme changing the protein's shape

Catalyst

______ an agent that speeds up a chemical reaction without itself being permanently altered

Transition State

The less stable state that occurs and is usually a high-energy state between reactants and products in a chemical reaction

Substrate orientation

When Enzyme bring together specific atoms into a correct position that are otherwise rotating and tumbling so that bonds can form

Protein Kinases

enzymes that reversibly activate or inactivate other proteins by adding phosphate groups to (phosphorylating) them

pH

After looking at the graph the enzyme activity of the the three different enzymes is being regulated by what variable

Temperature (variable affecting enzyme activity)

After looking at the shape of this graph, the enzyme activity of this enzyme is being regulated by what variable?

Substrate Concentration (variable affecting enzyme activity)

After looking at the shape of this graph, the enzyme activity of this enzyme is being regulated by what variable?

Metabolism

The totality of an organism's chemical reaction

Entropy

Disorder

Free energy

Energy that can do work

Negative ΔG - effect on spontaneity

Spontaneous

Energy releasing, Negative ΔG

Exergonic

Energy storing, Positive ΔG

Endergonic

Positive - effect of spontaneity

Not spontaneous

ΔG = ΔH - TΔS

Equation for ΔG

symbol G

Free energy

Symbol H

Enthalpy aka system's total energy

symbol T

Temperature

symbol S

Systems total entropy (disorder)

Adenine, ribose, phosphate group

ATP is composed of

Homeostasis

Maintaining a stable internal environment