BIOL212 Ch9

Vocabulary flashcards covering key terms and concepts from Campbell Biology Chapter 9, including redox reactions, glycolysis, pyruvate oxidation, the citric acid cycle, oxidative phosphorylation, and fermentation.

Fermentation

A catabolic process that causes a partial degradation of sugars that occurs without oxygen.

Aerobic Respiration

A catabolic pathway in which oxygen ($\text{O}_2$) is consumed as a reactant along with organic fuel to yield $\text{ATP}$.

Anaerobic Respiration

A catabolic process similar to aerobic respiration that yields energy but consumes compounds other than oxygen ($\text{O}_2$).

Cellular Respiration

The catabolic pathways of aerobic and anaerobic respiration, which break down organic molecules and use an electron transport chain for the production of $\text{ATP}$.

Redox Reactions

Chemical reactions that transfer electrons between reactants, also known as oxidation-reduction reactions.

Oxidation

The loss of electrons from a substance involved in a redox reaction.

Reduction

The addition of electrons to a substance involved in a redox reaction, which reduces the amount of positive charge on that substance.

Reducing Agent

The electron donor in a redox reaction that reduces the electron acceptor and becomes oxidized.

Oxidizing Agent

The electron acceptor in a redox reaction that oxidizes the electron donor and becomes reduced.

NAD+

Nicotinamide adenine dinucleotide, a coenzyme that functions as an electron carrier and oxidizing agent during cellular respiration.

Dehydrogenases

Enzymes that remove a pair of hydrogen atoms (two electrons and two protons) from a substrate, transferring two electrons and one proton to $\text{NAD}^+$ to form $\text{NADH}$.

Electron Transport Chain

A series of carrier molecules built into the inner mitochondrial membrane (or plasma membrane of prokaryotes) that break the fall of electrons to oxygen into energy-releasing steps.

Glycolysis

A metabolic pathway occurring in the cytosol that breaks down glucose into two molecules of pyruvate, producing a net yield of $2\,\text{ATP}$ and $2\,\text{NADH}$.

Citric Acid Cycle

An eight-step chemical cycle in the mitochondrial matrix that completes the metabolic breakdown of glucose by oxidizing acetyl $\text{CoA}$ to $\text{CO}_2$; also called the Krebs cycle.

Oxidative Phosphorylation

The production of $\text{ATP}$ using energy derived from the redox reactions of an electron transport chain and chemiosmosis.

Substrate-Level Phosphorylation

The enzyme-catalyzed formation of $\text{ATP}$ by direct transfer of a phosphate group to $\text{ADP}$ from an intermediate substrate in catabolism.

Energy Investment Phase

The initial phase of glycolysis during which $2\,\text{ATP}$ are consumed to split glucose into two three-carbon sugar molecules.

Energy Payoff Phase

The second phase of glycolysis during which $4\,\text{ATP}$ and $2\,\text{NADH}$ are generated as three-carbon sugars are oxidized to two molecules of pyruvate.

Acetyl CoA

Acetyl coenzyme A, the entry compound formed from pyruvate oxidation that feeds its acetyl group into the citric acid cycle.

Cytochromes

Iron-containing proteins that act as electron carriers in the electron transport chain.

ATP Synthase

A protein complex located in the inner mitochondrial membrane that uses energy from a proton gradient to synthesize $\text{ATP}$ from $\text{ADP}$ and inorganic phosphate.

Chemiosmosis

An energy-coupling mechanism that uses energy stored in a hydrogen ion ($\text{H}^+$) gradient across a membrane to drive cellular work, such as the synthesis of $\text{ATP}$.

Proton-Motive Force

The potential energy stored in the form of an electrochemical gradient of hydrogen ions ($\text{H}^+$) across a biological membrane.

Alcohol Fermentation

A type of fermentation in which pyruvate is converted to ethanol in two steps, releasing carbon dioxide ($\text{CO}_2$) and regenerating $\text{NAD}^+$.

Lactic Acid Fermentation

A type of fermentation in which pyruvate is reduced directly by $\text{NADH}$ to form lactate without generating carbon dioxide ($\text{CO}_2$).

Deamination

The enzymatic removal of amino groups from amino acids before they are processed as fuel in cellular respiration.

Beta Oxidation

A metabolic sequence that breaks fatty acids down to two-carbon fragments that enter the citric acid cycle as acetyl $\text{CoA}$, producing $\text{NADH}$ and $\text{FADH}_2$.