CHAPTER 7 PT. #1: Energy for Cells - Cellular Respiration

Vocabulary practice flashcards covering cellular respiration, redox reactions, mitochondrion anatomy, and the four phases of glucose breakdown.

Cellular Respiration

The metabolic process by which cells break down glucose and other organic molecules in steps to harvest energy and produce $\text{ATP}$.

Cellular Respiration Equation

The chemical equation represented as $\text{C}_6\text{H}_{12}\text{O}_6 + 6\,\text{O}_2 \rightarrow 6\,\text{CO}_2 + 6\,\text{H}_2\text{O} + \text{energy}$, in which glucose is oxidized and oxygen is reduced.

Oxidation in Cellular Respiration

The loss of hydrogen atoms and electrons during glucose breakdown, converting $\text{C}_6\text{H}_{12}\text{O}_6$ into $6\,\text{CO}_2$.

Reduction in Cellular Respiration

The gain of hydrogen atoms and electrons, converting $6\,\text{O}_2$ into $6\,\text{H}_2\text{O}$.

$$\text{NAD}^+$$

A coenzyme that accepts hydrogen atoms and electrons during cellular respiration to become reduced to $\text{NADH}$.

$$\text{FAD}^+$$

A coenzyme involved in redox reactions that combines with hydrogen atoms to form $\text{FADH}_2$.

Mitochondrion Structure

An organelle composed of a double membrane (outer and inner membrane), an intermembrane space, inner membrane folds called cristae, and an internal fluid-filled matrix.

Cristae

The internal folds of the mitochondrial inner membrane where the electron transport chain is located.

Matrix

The innermost fluid-filled space of a mitochondrion where the preparatory reaction and citric acid cycle take place.

Four Phases of Glucose Breakdown

The sequential stages of aerobic cellular respiration: glycolysis, preparatory reaction, citric acid cycle, and electron transport chain.

Glycolysis

The initial stage of glucose breakdown occurring in the cytoplasm that splits glucose into two molecules of pyruvate.

Energy-Investment Step

The first portion of glycolysis in which $2\,\text{ATP}$ are consumed to split glucose into two $\text{G3P}$ molecules.

Energy-Harvesting Step

The second portion of glycolysis in which oxidation yields $4\,\text{ATP}$, $2\,\text{NADH}$, and $2$ pyruvate molecules.

Substrate-Level ATP Synthesis

An enzymatic process in which a phosphate group is transferred directly from a high-energy substrate molecule to $\text{ADP}$, forming $\text{ATP}$.

$$\text{G3P}$$

Glyceraldehyde 3-phosphate; a three-carbon phosphorylated sugar molecule produced during the energy-investment step of glycolysis.

$$\text{BPG}$$

1,3-bisphosphoglycerate; a three-carbon intermediate produced during glycolysis that possesses high-energy phosphate groups.

$$\text{3PG}$$

3-phosphoglycerate; a three-carbon intermediate molecule formed during the energy-harvesting phase of glycolysis.

Pyruvate

The three-carbon end product of glycolysis; two molecules of pyruvate are generated per glucose molecule.

Glycolysis Totals

The overall inputs (glucose, $2\,\text{NAD}^+$, $2\,\text{ATP}$, $4\,\text{ADP} + 2\,\text{P}$) and outputs ($2$ pyruvate, $2\,\text{NADH}$, $2\,\text{ADP}$, $4\,\text{ATP}$), providing a net yield of $2\,\text{ATP}$.

Preparatory Reaction

The phase of cellular respiration in the mitochondrial matrix that converts pyruvate before entering the citric acid cycle, releasing $\text{CO}_2$.

Citric Acid Cycle

A cyclic pathway in the mitochondrial matrix that breaks down remaining carbon groups, yielding $\text{CO}_2$, $2\,\text{ATP}$, $\text{NADH}$, and $\text{FADH}_2$.

Electron Transport Chain

A series of electron carriers in the mitochondrial cristae that transfers high-energy electrons, consumes $\text{O}_2$ to form $\text{H}_2\text{O}$, and yields approximately $34\,\text{ATP}$.

Oxygen-Dependent Pyruvate Fate

If oxygen is available, pyruvate enters the mitochondria; if oxygen is absent, pyruvate undergoes reduction in the cytoplasm.