Metabolism, Nutrition, and Energetics

Flashcards covering key concepts from Chapter 25: Metabolism, Nutrition, and Energetics, including definitions of metabolic processes, cellular respiration steps, and ATP production.

What is metabolism defined as?

The sum of all chemical and physical changes that occur in body tissues.

What is catabolism?

The process of breaking larger molecules into smaller molecules, releasing energy that is used to synthesize ATP.

What is anabolism?

The process of building larger molecules from smaller molecules and atoms, requiring energy (most often ATP) to carry out cell functions.

What is the nutrient pool?

All available nutrient molecules distributed in blood, including water, vitamins, mineral ions, and organic molecules, obtained from food and used in metabolism.

What is oxidation in a chemical reaction?

The loss of hydrogen or electrons.

What is reduction in a chemical reaction?

The gain of hydrogen or electrons.

In redox reactions, what carries chemical energy?

Electrons.

How do reduced and oxidized atoms or molecules relate to energy?

A reduced atom or molecule gains energy, while an oxidized atom or molecule loses energy.

What is cellular respiration?

The catabolic reactions that occur in cells, breaking down carbohydrates, lipids, and proteins.

What are the three key steps of cellular respiration?

Glycolysis, Citric acid cycle, and Electron transport chain.

What is the overall chemical reaction for carbohydrate catabolism?

Glucose + oxygen → carbon dioxide + water.

Where does glycolysis occur?

In the cytosol.

Does glycolysis require oxygen?

No, it is an anaerobic reaction.

What is one 6-carbon glucose molecule broken down into during glycolysis?

Two 3-carbon molecules of pyruvic acid (pyruvate).

What coenzyme accepts hydrogen atoms during glycolysis?

NAD (nicotinamide adenine dinucleotide).

What is the net ATP production per glucose molecule from glycolysis?

2 ATP (4 produced, but 2 consumed).

How does pyruvate, produced in glycolysis, enter the mitochondrial matrix?

It permeates the outer mitochondrial membrane pores and is transported across the inner membrane by carrier proteins.

Where does the citric acid cycle (TCA cycle, Kreb’s cycle) occur?

In the mitochondrial matrix.

Does the citric acid cycle require oxygen?

Yes, it is an aerobic reaction.

What coenzymes accept hydrogen atoms during the citric acid cycle?

NAD (nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide).

What atoms are removed and released as CO2 during the citric acid cycle in a process called decarboxylation?

Carbon and oxygen atoms.

How many ATP are produced per glucose molecule during the citric acid cycle, and by what method?

2 ATP by direct transfer of a phosphate group (substrate level phosphorylation).

Where does oxidative phosphorylation and the electron transport chain (ETC) occur?

On the inner mitochondrial membrane.

Does the electron transport chain require oxygen?

Yes, it is an aerobic reaction.

What is the primary function of the electron transport chain regarding hydrogen atoms?

It transports electrons from hydrogen through a series of coenzymes and cytochromes to ultimately combine with hydrogen ions and oxygen to form water (2H2 + O2 → 2H2O).

How many ATP molecules are produced per glucose molecule by the electron transport chain?

30 to 32 ATP.

What percentage of total ATP is produced by the electron transport chain?

Over 90%.

What happens to hydrogen ions during the electron transport chain processes, leading to a steep concentration gradient?

They are pumped from the mitochondrial matrix into the intermembrane space.

What process allows hydrogen ions to diffuse back into the mitochondrial matrix, and what energy is used to phosphorylate ADP to ATP?

Hydrogen ions diffuse back through hydrogen ion channels, and the energy released by this diffusion is used to phosphorylate ADP to ATP.

How many ATP does each NADH and FADH2 yield in the electron transport chain?

Each NADH yields 2.5 ATP, and each FADH2 yields 1.5 ATP.

What is the net gain of ATP from the complete aerobic catabolism of one glucose molecule?

30-32 ATP.

Why does the reported ATP yield per glucose molecule vary in different sources (e.g., 30, 32, 34, 36, 38)?

ATP yield varies depending on whether electrons from glycolysis are transferred to NAD or FAD, and because membranes are leaky and transporting molecules around the cell expends energy.