Cellular Respiration and Fermentation Vocabulary

Vocabulary flashcards based on lecture slides covering cellular respiration, glycolysis, the Krebs cycle, the electron transport chain, and anaerobic fermentation.

Cellular Respiration

The chemical process that releases energy by breaking down food molecules (organic compounds) in the presence of oxygen, gradually converting ADP back into ATP.

Breathing

The physical process that allows animals and humans to come into contact with gases in the air.

Cytosol

The fluid and suspended molecules of salts, sugars, amino acids, and enzymes located around the organelles in a cell.

Cytoplasm

The cytosol plus the organelles suspended within it, comprising everything inside the plasma membrane except the nucleus.

Glycolysis

The first metabolic pathway of cellular respiration taking place in the cytosol, which breaks 1 molecule of glucose into 2 molecules of pyruvic acid with a net gain of 2 ATP molecules.

NAD+

Nicotinamide adenine dinucleotide; an electron carrier that accepts 4 high-energy electrons and transfers them to 2 NADH molecules and 2 $H^+$ during glycolysis.

Oxygen Catastrophe

The period 2 to 3 billion years ago when oxygen was gradually added to Earth's atmosphere by early photosynthetic bacteria, leading to the evolution of aerobic organisms.

Krebs Cycle

The second stage of cellular respiration, named after Hans Krebs, where pyruvic acid is broken down into carbon dioxide inside the mitochondrial matrix through a series of energy-extracting reactions.

Citric Acid

The first 6-carbon compound formed in the Krebs Cycle when Acetyl-CoA is added to a 4-carbon compound.

Acetyl-CoA

A compound formed when one carbon is removed from pyruvic acid (forming $CO_2$) and Coenzyme A (CoA) joins the remaining 2 carbons before entering the Krebs Cycle.

Electron Transport Chain

The pathway located in the inner membrane of mitochondria that uses high-energy electrons from NADH and FADH2 to pump $H^+$ ions across the membrane, establishing an electrochemical gradient.

ATP Synthase

An enzyme located in the inner mitochondrial membrane that utilizes the electrochemical gradient of $H^+$ ions to convert ADP into ATP.

Fermentation

An anaerobic process following glycolysis that releases energy from food molecules by passing high-energy electrons from NADH back to pyruvic acid, regenerating NAD+.

Alcoholic Fermentation

An anaerobic pathway used by yeast and micro-organisms represented by the equation $\text{pyruvic acid} + \text{NADH} \rightarrow \text{ethyl alcohol} + CO_2 + \text{NAD}^+$.

Lactic Acid Fermentation

An anaerobic pathway occurring in muscle cells during intense exercise represented by the equation $\text{pyruvic acid} + \text{NADH} \rightarrow \text{lactic acid} + \text{NAD}^+$.

Glycogen

A carbohydrate stored in muscles and tissues that supplies energy for 15-20 minutes of activity before the body begins breaking down fat.