Chapter 7 bio: Cellular Respiration

Vocabulary practice flashcards covering key definitions, pathways, enzymes, and mechanisms in Chapter 7 Cellular Respiration.

Acetyl CoA

The combination of an acetyl group derived from pyruvic acid and coenzyme A, which is synthesized from pantothenic acid (a B-group vitamin).

Aerobic Respiration

A biological process in which organisms convert energy from nutrients into ATP in the presence of oxygen.

Anaerobic

A term describing a biological process or cellular condition that occurs in the absence of oxygen.

Anaerobic Cellular Respiration

A metabolic process in which organisms convert energy for cellular use without utilizing molecular oxygen.

ATP Synthase

A membrane-embedded protein complex (also known as $F_1F_0$ ATP synthase) that catalyzes the formation of ATP from ADP and inorganic phosphate using the potential energy of a proton electrochemical gradient.

Chemiosmosis

The process by which ATP is synthesized in cellular metabolism driven by the flow of protons across a membrane down an electrochemical gradient.

Citric Acid Cycle

A closed loop of eight enzyme-catalyzed chemical reactions of central importance in all living cells that harvests chemical energy from carbohydrates via oxidation of acetyl groups, releasing $CO_2$ and producing $NADH$, $FADH_2$, and ATP or GTP.

Dephosphorylation

The chemical removal of a phosphate group from an organic molecule.

Fermentation

An anaerobic pathway that regenerates $NAD^+$ from $NADH$ using an endogenous organic or inorganic molecule as a final electron acceptor, allowing glycolysis to proceed without oxygen.

GLUT Protein

A family of integral membrane transport proteins responsible for facilitating the transport of glucose across the plasma membrane.

Glycolysis

A sequence of ten cytosolic enzyme-catalyzed reactions that splits one six-carbon glucose molecule into two three-carbon pyruvate molecules, generating a net yield of $2\,\text{ATP}$ and $2\,NADH$.

Isomerase

An enzyme that catalyzes the structural rearrangement of isomers, transforming one molecular isomer into another.

Krebs Cycle

An alternate name for the citric acid cycle, named in honor of Hans Krebs, who first elucidated the pathway in the 1930s using pigeon flight muscles.

Oxidative Phosphorylation

The production of ATP using energy derived from the transfer of electrons down the electron transport chain to oxygen and mediated by chemiosmosis.

Phosphorylation

The chemical addition of a phosphate group to a molecule, such as a protein, metabolic intermediate, or ADP.

Prosthetic Group

A non-polypeptide unit or molecule tightly bound to a protein (also termed a prosthetic cofactor) that is required for the protein's biological function.

Pyruvate

A three-carbon keto acid generated as the final output of glycolysis that undergoes decarboxylation and oxidation to produce acetyl CoA under aerobic conditions.

Redox Reaction

A paired chemical reaction involving the simultaneous transfer of electrons, consisting of an oxidation half-reaction coupled to a reduction half-reaction.

Substrate-Level Phosphorylation

The generation of ATP from ADP by direct transfer of a high-energy phosphate group from a phosphorylated metabolic intermediate catalyzed by an enzyme without requiring a membrane gradient.

TCA Cycle

An alternate designation for the citric acid cycle, named after the tricarboxylic acid nature of its initial intermediate, citrate.

Ubiquinone

A small, lipid-soluble electron transporter (often abbreviated as Q) located in the inner mitochondrial membrane that carries electrons from Complex I and Complex II to Complex III.

Reducing Agent

A compound capable of donating electron(s) to another substance in an oxidation-reduction reaction, becoming oxidized in the process.

Oxidizing Agent

A compound capable of accepting electron(s) from another substance in an oxidation-reduction reaction, becoming reduced in the process.

Electron Transport Chain

A series of protein complexes and mobile electron shuttles embedded within the inner mitochondrial membrane that transfer electrons from $NADH$ and $FADH_2$ to molecular oxygen while pumping protons into the intermembrane space.

Cytochrome Oxidoreductase

Complex III of the mitochondrial electron transport chain, composed of transmembrane cytochrome b, peripheral cytochrome c, and an iron-sulfur protein that transfers electrons to cytochrome c.

Lactic Acid Fermentation

An anaerobic pathway occurring in oxygen-deprived animal skeletal muscle cells, mammalian red blood cells, and certain bacteria, wherein pyruvate is reduced by lactate dehydrogenase to lactate to regenerate $NAD^+$.

Alcohol Fermentation

A two-reaction anaerobic pathway occurring in yeast in which pyruvate is decarboxylated by pyruvate decarboxylase to form acetaldehyde, which is then reduced by alcohol dehydrogenase to ethanol to regenerate $NAD^+$.

Phosphofructokinase

The key regulatory, rate-limiting glycolytic enzyme that catalyzes step 3 of glycolysis; it is activated by elevated fructose-6-phosphate and inhibited by high concentrations of ATP, citrate, and acidic pH.