Glycolysis
How many net ATP molecules result from glycolysis?
2 ATP
Where are the enzymes of the citric acid cycle located?
Mitochondrial matrix.
What drives ATP synthase to make ATP?
H⁺ ions flowing down their gradient through the enzyme.
Define a kilocalorie.
Heat needed to raise 1 kg of water by 1°C.
Define fermentation.
An anaerobic process that regenerates NAD⁺ so glycolysis can continue.
What does glycolysis convert glucose into?
Two three-carbon molecules (pyruvate).
Which of the following is not an end product of the citric acid cycle: CO₂, pyruvate, ATP, or FADH₂?
Pyruvate.
What would happen if mitochondria lacked an inner membrane?
Oxidative phosphorylation would completely fail.
Why do cells need ATP even though glucose contains lots of energy?
ATP provides small, usable packets of energy for cellular work.
Why do yeast produce alcohol only without oxygen?
Fermentation happens only in anaerobic conditions.
Does glycolysis require oxygen? Explain.
No. It’s anaerobic and occurs without oxygen.
What is acetyl-CoA’s role in the citric acid cycle?
It delivers carbon atoms to power the cycle.
During chemiosmosis, where are H⁺ ions pumped?
From the matrix to the intermembrane space.
When energy is released from glucose during cellular respiration, what carries it?
Electrons.
Why doesn’t yeast simply excrete pyruvate during fermentation?
Pyruvate must be converted to regenerate NAD⁺
After glycolysis but before the citric acid cycle, what happens to pyruvate?
It’s oxidized and converted into acetyl-CoA.
What electron carriers are produced by the citric acid cycle?
NADH and FADH₂.
Why is oxygen essential for oxidative phosphorylation?
It serves as the final electron acceptor, forming water.
What happens to most ATP if cellular respiration stops after glycolysis?
It isn’t produced; only 2 ATP come from glycolysis.
What type of organisms cannot survive in the presence of oxygen?
Obligate anaerobes.
What is the main purpose of NADH produced during glycolysis?
It carries electrons to the electron transport chain.
Why does the citric acid cycle require oxygen even though it does not directly use it?
Because NADH/FADH₂ must unload electrons into the ETC, which requires oxygen as final electron acceptor.
What portion of ATP from one glucose molecule is produced during oxidative phosphorylation?
The majority (≈26–28 ATP).
It isn’t produced; only 2 ATP come from glycolysis.
It houses the citric acid cycle and oxidative phosphorylation.
Compare the ATP yield of fermentation vs aerobic respiration.
Fermentation → 2 ATP; Aerobic respiration → ~32–36 ATP.