Chapter 4: Cell Respiration

Question 1

Cellular Respiration

Answer 1

Highly exergonic process by which a cell extracts energy from food and turns it into ATP.

Formula: C6H12O6 + 6O2 -> 6CO2 + 6H2O + ATP

Question 2

Anaerobic Cell Respiration

Answer 2

If there is no oxygen present, glycolysis is then followed by either lactic acid fermentation or alcohol fermentation.

Question 3

Aerobic Cell Respiration

Answer 3

Glycolysis is followed by Citric Acid Cycle (Krebs Cycle), and then the electron transport chain due to the presence of oxygen.

Question 4

ATP

Answer 4

Consists of adenosine and three phosphates. ATP is unstable, but becomes more stable as ADP with the removal of a phosphate (releases energy).

Question 5

Glycolysis

Answer 5

Breaks down one molecule of glucose into 2 molecules of pyruvic acid and net 2 ATP.

Occurs in the cytoplasm and does not require any oxygen.

Question 6

Substate Level Phosphorylation

Answer 6

Small amount of ATP is produced this way during glycolysis. Direct enzymatic transfer of a phosphate to ADP

Question 7

Structure of the Mitochondria

Answer 7

Has a double membrane and a folded cristae. The inner membrane has the outer compartment and the matrix. Krebs cycle takes place in the matrix, and e- transport takes place in the cristae.

Question 8

Citric Acid Cycle

Answer 8

Next step in aerobic cellular respiration. Takes place in the matrix of the mitochondria and requires pyruvate (from glycolysis). Each pyruvate must combine with coenzyme A to form acetyl coA. One pyruvate/acetyl coA = One turn of the Krebs cycle.

Each turn of the Krebs cycle creates 3 NADH, 1 ATP, and 1 FADH. The ATP is made by the substrate level phosphorylation.

Question 9

Electron Transport Chain

Answer 9

Proton pump in the mitochondria that has two reactions: one exergonic and one endergonic. Does not produce any ATP directly, but prepares to push protons across the membrane to achieve oxidative phosphorylation.

Theoretically, each NADH makes 3 ATP and each FADH2 makes 2 ATP.

Question 10

Oxidative Phosphorylation and Chemiosmosis

Answer 10

Powered by redox reactions. Because protons can’t diffuse through the membrane it goes through the ATP synthase channels (chemiosmosis, which is the key to ATP production).

As protons flow down the ATP synthase, they generate energy to change ADP to ATP.

Question 11

Summary of ATP Production

Answer 11

Substrate Level Phosphorylation: only a small of ATP is produced here. ATP is produced during glycolysis and the Krebs cycle.

Oxidative Phosphorylation: occurs during chemiosmosis, and makes most of the ATP. FAD and NADH lose protons, which makes a steep proton gradient, which powers the ATP synthase and changes the ADP to ATP.

Theoretically, 36-38 ATP can be made through aerobic cell respiration.

Question 12

Anaerobic Respiration, Fermentation

Answer 12

Consists of glycolysis + alcohol or lactic acid fermentation. Fermentation can produce ATP as long as there is enough NAD+ to accept electrons.

Question 13

Alcohol Fermentation

Answer 13

Process in which cells convert pyruvate from glycolysis into ethyl alcohol and carbon dioxide (NADH is oxidized back to NAD+). Example: yeast.

Question 14

Lactic Acid Fermentation

Answer 14

Pyruvate from glycolysis is turned into lactic acid, and NADH is oxidized back into NAD+. Human skeletal muscles carry out this process when there is not enough oxygen.