Energy I

Question 1

What is Catabolism?

Answer 1

Breakdown of complex molecules to release energy or carry out mechanical work

Question 2

What is Anabolism?

Answer 2

Synthesis of new molecules from less complex components

Question 3

How much ATP does the body contain and what does that mean?

Answer 3

Body only has 100g of ATP therefore ATP is resynthesized from ADP

Question 4

What is glucose metabolised into and why?

Answer 4

6C glucose molecule very unstable, therefore metabolised into 2 3C molecules

Question 5

What is the process where glucose is phosphorylated ?

Answer 5

○ The glucose is phosphorylated to glucose 6 phosphate
○ Fructose 6 phosphate is phosphorylated into fructose 1,6 biphosphate
○ This is an unstable compound therefore metabolises into 2 3C molecules

One is Glyceraldehyde 3 phosphate and the other is Dihydroxyacetone phosphate

Question 6

In glycolysis What is formed and what is it converted into?

Answer 6

Phosphoenol pyruvate is formed which is converted into phenol by loosing a phosphate and phosphorylating ADP.

Question 7

What else is formed in glycolysis?

Answer 7

2 ATP and 1 NADH formed

Question 8

What is the net gain in glycolysis?

Answer 8

Net gain of 2 ATP as there are 2 3C molecules which undergo the second step.

Question 9

What is glycolysis regulated by?

Answer 9

• Regulated by:
○ Reversible binding of allosteric effectors
○ Covalent modification
Transcription

Question 10

What does hexokinase do and what is it regulated by?

Answer 10

Hexokinase catalyses the phosphorylation of hexose sugars and is regulated by G6P

Question 11

What does phosphofructokinase do and what is it regulated by?

Answer 11

Phosphofructokinase converts fructose-6-phosphate to fructose-1,6-biphosphate and is regulated by ATP, citrate from TCA cycle, H+ ions and AMP

Question 12

What does pyruvate kinase do?

Answer 12

Pyruvate Kinase catalyses the phosphorylation of ADP by transferring the phosphate from phosphoenol pyruvate and is inhibited by high levels of ATP

Question 13

What does AMP stimulate?

Answer 13

Stimulates PFK

Question 14

How is AMP generated?

Answer 14

Hydrolysis of ADP

Question 15

What conditions inhibit PFK and why?

Answer 15

• High concentration of ATP and low pH inhibits PFK

Lowers affinity for Fructose 6 Phosphate

Question 16

What does the inhibition of PFK lead to?

Answer 16

Inhibition of PFK leads to inhibition of hexokinase

Question 17

What does a high concentration of ATP do?

Answer 17

High concentration of ATP inhibits PFK

Question 18

What does citrate inhibit?

Answer 18

PFK

Question 19

What is PFK indirectly stimulated by?

Answer 19

PFK is stimulated indirectly by a build up of F6P

Question 20

What is hexokinase inhibited by?

Answer 20

Hexokinase inhibited by G6P but not glucokinase

Question 21

Does glucokinase have a high Kt?

Answer 21

○ Glucokinase has a high Kt
§ Only active when glucose concentration are high
Allows liver to regulate blood glucose

Question 22

How are the energy needs for Exercising tissue and tumours met?

Answer 22

Energy needs met through anaerobic respiration

Question 23

What is reduced in anaerobic respiration and what does this result in exercising tissue and tumours?

Answer 23

Pyruvate is reduced resulting in the oxidation of NADH to form NAD and the formation of lactate

Question 24

What is required for anaerobic respiration?

Answer 24

NAD required for anaerobic respiration

Question 25

What is lactate and what does it inhibit?

Answer 25

Lactate is acidic and inhibits glycolysis therefore broken down in liver

Question 26

What type of growth is tumours?

Answer 26

Inappropriate growth

Question 27

What do tumours recruit?

Answer 27

Recruits blood vessels as it grows

Question 28

What can tumours outgrow and the consequence?

Answer 28

• Tumours can outgrow their blood supply reducing the oxygen delivery Therefore tumour cells revert to glycolysis

Question 29

What does the reduction in O2 lead to in tumours?

Answer 29

Reduction in O2 leads to the activation of the transcription of HIF-1α

Question 30

What does HIF-1a regulate?

Answer 30

HIF-1α regulates the expression of a number of enzymes in the glycolytic pathway