Biology 1203 Unit 8: Cellular Respiration and Energy Metabolism

Flashcards covering metabolism types, the stages of cellular respiration, ATP yields, and nutrient-specific metabolic pathways including carbohydrates, lipids, and proteins.

Metabolism

The sum total of all chemical reactions occurring within the body at all times that enable life.

Anabolic reactions

Chemical reactions that build large molecules from building blocks; these reactions require energy.

Catabolic reactions

Chemical reactions that break large complex molecules into small building blocks; these reactions release energy.

Cellular respiration

The process of nutrient breakdown accompanied by the synthesis of ATP.

Substrate level phosphorylation

The oxidation of nutrients to directly make ATP by transferring energy from chemical bonds to ADP and $Pi$.

Oxidative phosphorylation

A process where nutrient oxidation releases high-energy electrons used to produce ATP via the electron transport chain and chemiosmosis.

Reduction

A chemical reaction involving the gain of electrons, leading to an increase in potential energy.

Oxidation

A chemical reaction involving the loss of electrons, leading to a decrease in potential energy.

Co-enzyme

A molecule used by an enzyme to assist in a reaction, such as $NAD^+$ or FAD, which act as electron carriers or little buckets of energy.

Glycolysis

A multi-step process occurring in the cytoplasm that converts one 6-carbon glucose molecule into two 3-carbon pyruvic acid molecules, yielding a net of 2 ATP and 2 NADH.

Pyruvic acid oxidation

The transition step in the mitochondrial matrix where each pyruvic acid is oxidized to form acetyl-CoA, producing 1 $CO_2$ and 1 NADH per pyruvate.

Krebs cycle

Also called the citric acid cycle; a mitochondrial matrix pathway that begins and ends with oxaloacetic acid, producing $CO_2$, ATP, NADH, and $FADH_2$.

Chemiosmosis

A component of oxidative phosphorylation where the movement of $H^+$ ions through ATP synthase generates ATP.

Aerobic respiration

The process of cellular respiration that requires oxygen as the final electron acceptor, yielding approximately 32 ATP per glucose molecule.

Anaerobic respiration

The breakdown of glucose in the absence of oxygen, converting pyruvate to lactate to regenerate $NAD^+$ and producing only 2 ATP net.

Glycogenesis

The process of converting excess glucose into glycogen for storage in the liver and skeletal muscles.

Glycogenolysis

The breakdown of stored glycogen back into glucose when blood glucose levels fall.

Gluconeogenesis

A process occurring in the liver where new glucose is synthesized from non-carbohydrate sources like lactic acid, glycerol, or amino acids.

Lipolysis

The breakdown of triglycerides into glycerol and individual fatty acids when glucose levels fall.

Beta-oxidation

The process where individual fatty acids are broken down into acetyl-CoA molecules in the mitochondria.

Ketogenesis

The production of ketone bodies (acetoacetate, 3-hydroxybutyrate, and acetone) by the liver when an excess of acetyl-CoA accumulates.

Ketoacidosis

A potentially deadly condition caused by an accumulation of acidic ketone bodies in the blood, often due to starvation or uncontrolled diabetes mellitus.

Deamination

The removal of an amino group from an amino acid, which must occur before the molecule can be oxidized for energy.

Absorptive state

The metabolic state following a meal where nutrients are absorbed, insulin is secreted, and the body focuses on glucose uptake and energy storage.

Postabsorptive state

The metabolic state between meals where no nutrients enter from the digestive system, glucagon is secreted, and the body mobilizes stored energy.