Cellular Respiration and Endosymbiosis Notes

Flashcards covering key vocabulary and concepts from the lecture notes on cellular respiration and endosymbiosis.

Cellular Respiration

The process by which organisms convert glucose and oxygen into energy, carbon dioxide, and water.

Glycolysis

The first stage of cellular respiration that breaks down glucose into two molecules of pyruvate.

Endosymbiosis

A symbiotic relationship theory proposing that certain organelles originated from free-living prokaryotes engulfed by ancestral eukaryotic cells.

Pyruvate

A three-carbon molecule produced from the breakdown of glucose during glycolysis.

ATP Synthase

An enzyme complex that produces ATP from ADP and inorganic phosphate during cellular respiration.

Catabolism

Metabolic pathways that break down molecules into smaller units, releasing energy.

Aerobic Respiration

The process of producing cellular energy in the presence of oxygen, resulting in the oxidation of pyruvate to Acetyl CoA.

Fermentation

A metabolic process that converts sugar to acids, gases, or alcohol in the absence of oxygen, producing ATP.

NADH

The reduced form of NAD⁺, which acts as an electron carrier in metabolic reactions.

Acetyl CoA

A molecule derived from pyruvate that enters the citric acid cycle for further energy extraction.

What is glycolysis?

Glycolysis is the metabolic pathway that converts glucose into pyruvate, producing a small amount of ATP and NADH in the process.

What are the main steps of glycolysis?

Glycolysis consists of 10 main steps divided into two phases: the energy investment phase and the energy payoff phase.

Step 1 of glycolysis

Glucose is phosphorylated to glucose-6-phosphate by the enzyme hexokinase, using one ATP.

Step 2 of glycolysis

Glucose-6-phosphate is converted to fructose-6-phosphate by the enzyme phosphoglucose isomerase.

Step 3 of glycolysis

Fructose-6-phosphate is phosphorylated to fructose-1,6-bisphosphate by the enzyme phosphofructokinase, using one ATP.

Step 4 of glycolysis

Fructose-1,6-bisphosphate is split into two three-carbon molecules: dihydroxyacetone phosphate and glyceraldehyde-3-phosphate by the enzyme aldolase.

Step 5 of glycolysis

Dihydroxyacetone phosphate is converted into glyceraldehyde-3-phosphate by the enzyme triose phosphate isomerase.

Step 6 of glycolysis

Glyceraldehyde-3-phosphate is oxidized and phosphorylated to 1,3-bisphosphoglycerate, producing NADH by the enzyme glyceraldehyde-3-phosphate dehydrogenase.

Step 7 of glycolysis

1,3-bisphosphoglycerate is converted to 3-phosphoglycerate by the enzyme phosphoglycerate kinase, producing ATP.

Step 8 of glycolysis

3-phosphoglycerate is converted to 2-phosphoglycerate by the enzyme phosphoglycerate mutase.

Step 9 of glycolysis

2-phosphoglycerate is dehydrated to phosphoenolpyruvate by the enzyme enolase.

Step 10 of glycolysis

Phosphoenolpyruvate is converted to pyruvate by the enzyme pyruvate kinase, producing ATP.

What is pyruvate oxidation?

Pyruvate oxidation is the process in which pyruvate, produced from glycolysis, is converted into acetyl-CoA, which enters the citric acid cycle.

What are the main steps of pyruvate oxidation?

Pyruvate oxidation involves three main steps: decarboxylation, reduction of NAD+, and formation of acetyl-CoA.

Step 1 of pyruvate oxidation

Decarboxylation: Pyruvate (a three-carbon molecule) is decarboxylated, releasing one molecule of carbon dioxide (CO₂) by the enzyme pyruvate dehydrogenase.

Step 2 of pyruvate oxidation

Reduction of NAD+: During this process, NAD+ is reduced to NADH, capturing high-energy electrons.

Step 3 of pyruvate oxidation

Formation of acetyl-CoA: The remaining two-carbon molecule, acetyl, combines with coenzyme A (CoA) to form acetyl-CoA, which then enters the citric acid cycle