metabolism and survival: Key area 2

Question 1

What is cellular respiration?

Answer 1

Cellular respiration is a series of metabolic pathways which brings about the release of energy. It consists of a series of enzyme controlled reactions that release the energy contained in food by oxidation.

Question 2

When is energy held in an ATP molecule released?

Answer 2

When the band attaching the terminal phosphate is broken by enzyme action.

Question 3

Why is ATP important?

Answer 3

ATP is important because its essential to biological systems as it acts as the link between catabolic energy releasing reactions and those that use energy (anabolic)

Question 4

Why is ATP known as “the energy currency” of the cell?

Answer 4

As it is spent during cellular work such as muscular contraction or the formation of proteins, and is “banked” or stored when glucose is broken down in cellular respiration.

Question 5

What happens when glucose is broken down in the cell?

Answer 5

It releases energy which is used to produce ATP. Many molecules of ATP are present in a living cell.

Question 6

What three set of reactions occur in cellular respiration?

Answer 6

1. Glycolysis
2. The citric acid cycle
3. The electron transport chain.

Question 7

Where does Glycloysis take place?

Answer 7

In the cytoplasm of the cell and doesnt require oxygen.

Question 8

What is Glycolysis?

Answer 8

It is the breakdown, in a series of enzyme catalysed reactions, of the sugar glucose into two molecules called pyruvate.

Question 9

What starts off the process? (Glycolysis)

Answer 9

To start the process off, energy from two ATP molecules is needed. This can be thought of as energy investment phase where ATP is used to phosphorylate intermediates in glycolysis.

Question 10

How many ATP molecules does Glycolysis produce?

Answer 10

The series of reactions eventually produces four ATP molecules, so there is a net gain of two ATP from glycolysis. (energy pay off stage)

Question 11

What happens in the transformation of glucose into pyruvate?

Answer 11

Dehydrogenase enzymes remove hydrogen ions and high energy electrons that are passed to a coenzyme called NAD which is reduced to form NADH.

Question 12

What happens in a later process in cell respiration?

Answer 12

The NADH will be used to produce ATP.

Question 13

If oxygen is present in Glycolysis what happens to pyruvate?

Answer 13

It progresses to the Citric Acid Cycle.

Question 14

Is oxygen required for glycolysis?

Answer 14

No.

Question 15

Name the final product of glycolysis.

Answer 15

Pyruvate.

Question 16

Describe the mitochondria.

Answer 16

The Mitochondria possess a double membrane. The inner membrane of each mitochondrion is folded into many cristae, which provide a large surface area.

Question 17

What respiration process occurs in the mitochondira?

Answer 17

The Electron Transport Chain.

Question 18

What happens in the electron transport chain?

Answer 18

Pyruvate diffuses into the matrix of the mitochondrion, where it is broken down into an acetyl group.

Question 19

Name the molecule produced when oxaloacetate combines with acetyl CoA.

Answer 19

ATP.

Question 20

Is the citric acid cycle an aerobic or anaerobic process?

Answer 20

Aerobic.

Question 21

What is the Electron Transport Chain?

Answer 21

It’s a series of proteins in the inner mitochondrial membrane.

Question 22

What happens with the Hydrogen ions and electrons that have been transferred to NAD and FAD?

Answer 22

They are passed to the Electron Transport Chain.

Question 23

What happens with the NAD and FAD passed on to the Electron Transport Chain?

Answer 23

They will be used to release energy for ATP production.

Question 24

What happens to the carbon dioxide in the Citric Acid Cycle?

Answer 24

It diffuses out the cell as a waste product, and is expired from the organism by breathing out or by diffusion over the body surface.

Question 25

Why is oxygen needed in The Electron Transport Chain?

Answer 25

Without the CAC and ETC cannot function!
Oxygen is needed to oxidise pyruvate to yield 36 ATP.
With 2 ATP from glycolysis (doesn’t require O2) the yield from one glucose molecule oxidised is 38 ATP.