Unit 3: Cellular Energetics (copy)

Bioenergetics

The study of how cells accomplish energy transformation.

First Law of Thermodynamics

Energy cannot be created or destroyed; it can only be transferred.

Second Law of Thermodynamics

Energy transfer leads to less organization; the universe tends toward disorder (entropy).

Exergonic reactions

Reactions in which the products have less energy than the reactants.

Endergonic reactions

Reactions that require an input of energy, where products have more energy than the reactants.

Catalyst

A substance that speeds up a chemical reaction.

Enzyme specificity

The concept that each enzyme catalyzes only one kind of reaction.

Active site

A special region on an enzyme where substrates bind and reactions occur.

Induced-fit model

The concept that enzymes change shape slightly to accommodate substrates.

Cofactors

Factors that assist enzymes in catalyzing reactions; can be organic molecules (coenzymes) or inorganic molecules.

Denaturation

The process where an enzyme loses its shape and functionality due to changes in temperature or pH.

Saturation point

The substrate concentration at which all enzyme active sites are occupied, and the reaction rate plateaus.

Competitive inhibition

A situation where an inhibitor binds to the active site, blocking the substrate from binding.

Noncompetitive inhibition

An inhibitor that binds to an allosteric site, changing the enzyme shape and inhibiting function without blocking the active site.

ATP (adenosine triphosphate)

The primary energy carrier in cells, consisting of adenosine and three phosphate groups.

Cellular respiration

The process by which cells break down glucose and produce ATP.

Photosynthesis

The process by which light energy is converted into chemical energy in the form of glucose.

Calvin-Benson Cycle

The light-independent reactions of photosynthesis where CO2 is fixed into carbohydrates.

Aerobic respiration

Respiration that occurs in the presence of oxygen, involving glycolysis, the Krebs cycle, and oxidative phosphorylation.

Anaerobic respiration

Respiration occurring without oxygen; involves glycolysis and fermentation processes.

Photolysis

The splitting of water molecules to replenish electrons in the photosystem during photosynthesis.

Chemiosmosis

The process of ATP production by the movement of hydrogen ions across a membrane, driven by the electron transport chain.