1.7 - Cellular Respiration

Question 1

Process of respiration

Answer 1

Respiration is the process by which energy is released from food.

It occurs in all living cells.

Question 2

What is respiration

Answer 2

Respiration is a metabolic pathway. It consists of a series of chemical reactions, each catalysed by specific enzymes.

Question 3

What is the main substrate within respiration?

Answer 3

The main substrate within the respiration pathway is glucose.

Question 4

What are the parts of the metabolic pathway involved in respiration?

Answer 4

1. Glycolysis
2. Citric acid cycle
3. Electron transport chain

Question 5

What is phosphorylation?

Answer 5

Phosphorylation is an enzyme control process by which a phosphate group is added to a molecule.

Example of phosphorylation:
When low energy ADP and Pi combine to form high energy ATP

Question 6

What is glycolysis

Answer 6

Glycolysis is the first stage of respiration which takes place in the cytoplasm and does not require oxygen.

Question 7

Respiration metabolic pathway oxygen requirements

Answer 7

Glycolysis - no

Citric acid cycle - yes
Electron transport chain - yes

Question 8

What does glycolysis involve?

Answer 8

Glycolysis involves the breakdown of glucose into two pyruvate molecules.

Glycolysis involves 2 phases:

• an energy investment phase
• an energy payoff stage

Question 9

Glycolysis - production of pyruvate

Answer 9

The production of pyruvate from glucose involves the production of several intermediate molecules.

Question 10

Glycolysis- what is required for the phosphorylation of glucose

Answer 10

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 payoff stage and results in a net gain of ATP.

Question 11

What happens during the energy payoff stage?

Answer 11

During the energy payoff phase of glycolysis (and in the citric acid cycle), dehydrogenase enzymes remove hydrogen ions and electrons and pass them to the coenzyme NAD, forming NADH.

Question 12

What enzyme removes hydrogen ions and electrons and where do they pass them

Answer 12

Dehydrogenase enzymes remove hydrogen ions and electrons and pass them to the coenzyme NAD, forming NADH.

Question 13

In what conditions is pyruvate broken down into an acetyl group?

Answer 13

Aerobic (oxygen present)

Question 14

What happens to pyruvate in aerobic conditions?

Answer 14

In aerobic conditions, pyruvate is broken down into an acetyl group.

Question 15

Once pyruvate has been broken down into an acetyl group what happens to the acetyl group?

Answer 15

The acetyl group then combines with coenzyme A to form acetyl coenzyme A.

Question 16

What is the next stage of respiration after glycolysis?

Answer 16

Citric acid cycle

Question 17

What needs to be present for the citric acid cycle to take place?

Answer 17

The citric acid cycle only occurs of oxygen is present.

Question 18

Where does the citric acid cycle take place in the cell?

Answer 18

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

Question 19

What is the citric acid cycle controlled by?

Answer 19

The citric acid cycle is controlled by enzymes including dehydrogenases. 

Question 20

What happens to the acetyl group in the citric acid cycle?

Answer 20

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

Question 21

What happens to citrate in the citric acid cycle?

Answer 21

During a series of enzyme controlled steps, citrate is gradually converted back into oxaloacetate which results in the generation of ATP and releases carbon dioxide.

Question 22

What do dehydrogenase enzyme is do during the citric acid cycle?

Answer 22

Dehydrogenase enzymes remove hydrogen ions and electrons and pass them to the coenzyme NAD, forming NADH.

Question 23

What happens to the hydrogen ions and electrons from NADH?

Answer 23

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

Question 24

What is the last stage of glycolysis?

Answer 24

The electron transport chain is the last stage of respiration requires oxygen to be present.

Question 25

Where does the electron transport chain take place

Answer 25

The electron transport chain takes place in the inner membrane of the mitochondria.

Question 26

What is the ETC?

Answer 26

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



Question 27

What stage is most ATP made

Answer 27

The electron transport chain is the final stage of respiration where most of the ATP is made

Question 28

How is ATP made in the ETC

Answer 28

ATP is made using the energy from the electrons which have been removed during glycolysis and the citric acid cycle.

Question 29

ETC: ATP synthesis process

Answer 29

• Electrons are passed alone electron transport chain releasing energy.
• this energy allows hydrogen ions to be pumped across the inner mitochondrial membrane.
• The flow of hydrogen ions back through the membrane protein ATP synthase results in the production of ATP.
• finally the hydrogen ions and electrons combine with oxygen to form water.

Question 30

What is the final hydrogen acceptor in the ETC?

Answer 30

Oxygen is the final hydrogen acceptor of the electron transport chain.

Question 31

What is the role of ATP in the transfer of energy?

Answer 31

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

Question 32

Cellular process that require energy

Answer 32

Muscle cell contraction

Transmission of nerve impulses

Cell division

Protein synthesis