unit: 2 - Cellular respiration

Question 1

What is ATP, and why is it important in cellular respiration?

Answer 1

ATP (adenosine triphosphate) is the primary energy carrier in cells, providing energy for biological processes such as muscle contraction, active transport, and biosynthesis.

Question 2

How is energy stored in ATP?

Answer 2

Energy is stored in the high-energy phosphate bonds, particularly the bond between the second and third phosphate groups.

Question 3

What happens when ATP is hydrolyzed?

Answer 3

ATP is converted to ADP (adenosine diphosphate) and an inorganic phosphate (Pi), releasing energy for cellular work

Question 4

How is ATP regenerated?

Answer 4

ATP is regenerated by adding a phosphate group to ADP using energy from cellular respiration, particularly during oxidative phosphorylation.

Question 5

What is the role of ATP in active transport?

Answer 5

ATP provides energy to power protein pumps that move molecules across membranes against their concentration gradients.

Question 6

What is the overall chemical equation for cellular respiration?

Answer 6

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ~38 ATP

Question 7

What are the three main stages of cellular respiration?

Answer 7

A: 1. Glycolysis
2. Krebs Cycle (Citric Acid Cycle)
3. Electron Transport Chain (ETC) and Oxidative Phosphorylation.

Question 8

What happens during glycolysis?

Answer 8

Glucose (C₆H₁₂O₆) is broken down into two molecules of pyruvate, producing 2 ATP and 2 NADH.

Question 9

Where does the Krebs Cycle occur, and what does it produce?

Answer 9

The Krebs Cycle occurs in the mitochondrial matrix and produces 2 ATP, 6 NADH, 2 FADH₂, and CO₂ as a waste product.

Question 10

What is the role of the electron transport chain (ETC)?

Answer 10

The ETC, located in the inner mitochondrial membrane, uses electrons from NADH and FADH₂ to pump protons and create a proton gradient for ATP synthesis.

Question 11

What is oxidative phosphorylation?

Answer 11

The process where ATP is synthesized as protons flow back into the mitochondrial matrix through ATP synthase, driven by the proton gradient created by the ETC.

Question 12

What is the role of oxygen in cellular respiration?

Answer 12

Oxygen acts as the final electron acceptor in the ETC, combining with electrons and protons to form water.

Question 13

How does anaerobic respiration differ from aerobic respiration?

Answer 13

Anaerobic respiration does not use oxygen, producing less ATP and byproducts like lactic acid (in animals) or ethanol and CO₂ (in yeast).

Question 14

What is the importance of NADH and FADH₂ in respiration?

Answer 14

NADH and FADH₂ carry high-energy electrons to the ETC, where their energy is used to generate ATP.

Question 15

What is glycolysis?

Answer 15

Glycolysis is the breakdown of glucose to pyruvate in the cytoplasm.

Question 16

What happens to pyruvate in aerobic conditions?

Answer 16

In aerobic conditions, pyruvate is broken down to an acetyl group that combines with coenzyme A forming acetyl coenzyme A.

Question 17

What’s required for phosphorylation?

Answer 17

ATP is required for the phosphorylation of glucose and intermediates during the energy investment phase of glycolysis. This leads to the generation of more ATP during the energy pay-off stage and results in a net gain of ATP.

Question 18

What does acetyl coenzyme A combine with oxaloacetate to make?

Answer 18

In the citric acid cycle, the acetyl group from acetyl coenzyme A combines with oxaloacetate to form citrate.

Question 19

Where does Krebs cycle occur?

Answer 19

The citric acid cycle occurs in the matrix of the mitochondria.

Question 20

Where are hydrogen and electrons from NADH passed through?

Answer 20

The hydrogen ions and electrons from NADH are passed to the electron transport chain on the inner mitochondrial membrane.

Question 21

What’s the electron transport chain?

Answer 21

The electron transport chain is a series of carrier proteins attached to the inner mitochondrial membrane.

Question 22

How do we use the energy released from ATP synthesis?

Answer 22

This energy allows hydrogen ions to be pumped across the inner mitochondrial membrane. The flow of these ions back through the membrane protein ATP synthase results in the production of ATP.

Question 23

How does ATP synthesis release energy?

Answer 23

During ATP synthesis electrons are passed along the electron transport chain releasing energy.

Question 24

Electrons, and hydrogen ions form what product?

Answer 24

Finally, hydrogen ions and electrons combine with oxygen to form water

Question 25

What occurs when there’s no oxygen, and where does it happen?

Answer 25

In the absence of oxygen, fermentation takes place in the cytoplasm.

Question 26

Is pyruvate to lactate a reversible reaction?

Answer 26

In animal cells, pyruvate is converted to lactate in a reversible reaction.

Question 27

What do plants and yeast make?

Answer 27

In plants and yeast, ethanol and CO2 are produced in an irreversible reaction.

Question 28

Does fermentation result in more or less ATP being produced than aerobic respiration?

Answer 28

Fermentation results in much less ATP being produced than in aerobic respiration

Question 29

What is ATP used for?

Answer 29

ATP is used to transfer energy to cellular processes which require energy.