Biology 2E Chapter 7 - Cellular Respiration

Vocabulary-style flashcards covering the stages of cellular respiration, redox reactions, electron carriers, and regulatory mechanisms based on the Chapter 7 lecture.

Cellular Respiration

The process by which cells extract energy from food to generate ATP, also known as glucose catabolism.

Redox Reactions

Chemical reactions where electrons are transferred from one molecule to another.

Reducing Agents

Molecules that can donate electron(s) in a redox reaction.

Oxidizing Agents

Molecules that can accept electrons in a redox reaction.

Reduced

The state of a molecule that has gained electron(s) after a chemical reaction.

Oxidized

The state of a molecule that has lost electron(s) after a chemical reaction.

NAD+

The oxidized state of nicotinamide adenine dinucleotide, which acts as an electron carrier by accepting electrons.

NADH

The reduced state of nicotinamide adenine dinucleotide, which carries $2\,e^-$ and $1\,H^+$ more than its oxidized form.

Dephosphorylation

The loss of a phosphate group from a molecule.

Phosphorylation

The process of adding a phosphate group to a molecule; phosphorylated molecules tend to be less stable and more likely to react.

Chemiosmosis

A process that generates $90\%$ of ATP using the enzyme ATP synthase and a $H^+$ concentration gradient; it occurs in mitochondria, chloroplasts, and plasma membranes of aerobic prokaryotes.

ATP Synthase

An integral membrane protein and enzyme that mediates the reaction $ADP + Pi \rightarrow ATP$ using kinetic energy from protons.

Glycolysis

The first metabolic pathway of glucose metabolism, occurring in the cytoplasm, involving 10 enzymatic reactions and not requiring $O_2$.

Glyceraldehyde-3-phosphate (G3P)

The two three-carbon molecules formed when glucose is phosphorylated and split during the first half of glycolysis.

Net ATP production of glycolysis

$2\,ATP$ ($4\,ATP$ produced minus $2\,ATP$ invested).

Oxidation of Pyruvate

The process in eukaryotic cells where, if oxygen is present, two pyruvate molecules enter the mitochondria and are converted to acetyl CoA.

Citric Acid Cycle (CAC)

A continuous cycle occurring in the mitochondrial matrix where acetyl CoA and oxaloacetate form citrate, which is then oxidized to produce NADH, $FADH_2$, and ATP/GTP.

Oxaloacetate

The final product of the citric acid cycle that also combines with the acetyl group in the first step.

Oxidative Phosphorylation

The last pathway of cellular respiration consisting of the electron transport chain and chemiosmosis; it is the only pathway where $O_2$ is an input.

Electron Transport Chain (ETC)

A series of electron transporters embedded in the inner mitochondrial membrane that shuttle electrons from NADH and $FADH_2$ to $O_2$, pumping protons in the process.

Ubiquinone (Q)

A component of the ETC that carries electrons from complexes I and II to complex III.

Cytochrome C

A peripheral protein that carries each individual electron from complex III to complex IV.

Final Electron Acceptor

Oxygen ($O_2$), which is reduced at complex IV to form $H_2O$.

ATP Yield per Glucose

$30$-$36$ ATP per glucose molecule, storing ~$34\%$ of the energy from glucose.

Fermentation

A metabolic process that regenerates NAD+ from NADH when $O_2$ is lacking, allowing glycolysis to continue.

Lactic Acid Fermentation

A type of substrate-level phosphorylation occurring when $O_2$ is limited in muscle cells, red blood cells, and some bacteria; catalyzed by lactate dehydrogenase.

Alcohol Fermentation

A two-reaction process in anaerobic yeast involving pyruvate decarboxylase and alcohol dehydrogenase to produce ethanol and $CO_2$.

Glut4

A protein residing in vesicles that fuses with the plasma membrane in the presence of insulin to allow glucose into the cell.

Hexokinase

An enzyme in glycolysis that is inhibited by elevated levels of glucose-6-phosphate.

Phosphofructokinase

The glycolysis enzyme whose activity is increased by fructose-6-phosphate and decreased by citrate or acidic pH.