Cellular Respiration

Lecture 4a: Cellular Respiration

What type of reaction is cellular respiration?

Catabolic reaction that breaks down glucose for energy.

What is the overall equation for cellular respiration?

C₆H₁₂O₆ + O₂ → CO₂ + H₂O + ATP.

What happens to unused energy from glucose?

Released as heat.

How is energy split between ATP and heat?

~40% ATP, ~60% heat.

Where does glycolysis occur?

Cytoplasm.

Where do the citric acid cycle and ETC occur?

Mitochondria.

Does glycolysis require oxygen?

No (anaerobic).

What molecule is glucose split into during glycolysis?

2 pyruvate.

What are the products of glycolysis?

2 ATP, 2 NADH, 2 pyruvate.

How many carbons are in glucose vs pyruvate?

Glucose = 6; Pyruvate = 3.

Where does the citric acid cycle occur?

Mitochondrial matrix.

What are the main products of the citric acid cycle per glucose?

2 ATP, 8 NADH, 2 FADH₂, CO₂.

What happens to carbons from glucose in this cycle?

Released as CO₂.

What do NADH and FADH₂ provide to the ETC?

Electrons and hydrogen ions.

What molecule accepts the final electrons in the ETC?

Oxygen.

What byproduct forms when oxygen accepts electrons and H⁺?

Water (H₂O).

About how many ATP are produced in the ETC?

28–32 ATP.

How many ATP come from one glucose molecule overall?

About 32–36 ATP.

How many ATP are produced without oxygen?

Only 2 ATP.

What does pyruvate turn into when no oxygen is present?

Lactic acid.

Why is fermentation important for glycolysis?

Regenerates NAD⁺.

What happens to lactic acid once oxygen returns?

Converted back to pyruvate.

What other macromolecule besides glucose can fuel respiration?

Fats (and proteins).

Why do fats yield more energy than carbs?

Produce many pyruvates → ~6x more ATP.