Cellular Respiration Part 2: The Citric Acid Cycle

The video tutorial explains the citric acid cycle, starting with glycolysis, an anaerobic process that allowed early organisms to generate energy. As oxygen became abundant due to photosynthesis, aerobic respiration evolved, occurring in mitochondria. The video details the conversion of pyruvate to acetyl-CoA and the eight steps of the citric acid cycle, highlighting the enzymes involved. The cycle produces NADH, FADH2, and ATP, which are crucial for oxidative phosphorylation, the main ATP-generating process in aerobic respiration.

What is the primary reason early organisms relied on glycolysis for energy?

• It is a complex process.

• It occurs in the mitochondria.

• It does not require oxygen.

• It produces a large amount of ATP.

What is the role of coenzyme A in the conversion of pyruvate?

• It oxidizes pyruvate.

• It attaches to pyruvate to form acetyl-CoA.

• It decarboxylates pyruvate.

• It converts pyruvate to glucose.

Which enzyme is responsible for converting citrate to isocitrate?

• Citrate synthase

• Aconitase

• Isocitrate dehydrogenase

• Fumarase

During the citric acid cycle, which molecule is produced alongside fumarate?

• ATP

• GTP

• NADH

• FADH2

What is the final product of the citric acid cycle that allows it to restart?

• Alpha-ketoglutarate

• Oxaloacetate

• Malate

• Citrate