Unit 1- Cellular Respiration

Question 1

Describe the energy difference in the formation of ATP and ADP+Pi

Answer 1

ATP to ADP +Pi releases energy. ADP+Pi to ATP requires energy.

Question 2

Describe phosphorylation.

Answer 2

Phosphorylation is an enzyme controlled process by which a phosphate group is added to a molecule (eg. Pi + ADP = ATP).

Question 3

What are the 3 stages of aerobic respiration? In what order?

Answer 3

Glycolysis, citric acid cycle, electron transport chain.

Question 4

What is glycolysis?

Answer 4

The breakdown of glucose to pyruvate in cytoplasm. Two stages: energy investment stage, energy pay off stage. Occurs in the cytoplasm and doesn’t require oxygen.

Question 5

Describe the energy investment stage.

Answer 5

ATP is required for the phosphorylation of glucose and intermediates during the energy investment phase. Glucose breaks down into intermediate compounds along with 2 ATP to 2ADP.

Question 6

Describe the energy pay off stage.

Answer 6

Phosphorylation (addition of a phosphate) in the energy investment phase leads to the generation of more ATP during the energy pay off phase and results in a net gain of ATP. Intermediate compounds break down into pyruvate and 4 ADP + Pi = 4ATP. And 2NAD = NADH by dehydrogenase.

Question 7

Describe the role of dehydrogenase in glycolysis.

Answer 7

Hydrogen ions and associated electrons are removed from intermediates of glycolysis by dehydrogenase enzyme and transferred to the co enzyme NAD, forming NADH taken to the electron transport chain.

Question 8

Describe the events of the citric acid cycle.

Answer 8

1. Pyruvate is broken down to an acetyl group, which combines with coenzyme A to form acetyl coenzyme A.
2. This then combines with oxaloacetate (4C) to form citrate(6C). This is followed by a series of enzyme controlled steps which regenerates oxaloacetate and produces CO2, NADH and ATP.
3. Takes place in the matrix of the mitochondria, requires oxygen.

Question 9

Describe the events of the electron transport chain.

Answer 9

1. The electron transport chain is a series of carrier proteins attached to the inner mitochondrial membrane.
2. The electrons carried by NADH are passed along the electron transport chain releasing energy.
3. The energy allows hydrogen ions to be pumped across the inner mitochondrial membrane.
4. The return flow of hydrogen ions back through the membrane protein ATP synthase results in the production of ATP.
5. Hydrogen ions and electrons combine with oxygen to form water.