Energy (Metabolism)

Question 1

What is METABOLISM?

Answer 1

the CHEMICAL PROCESSES that occur within a living organism in order to MAINTAIN LIFE.

Question 2

What are the two types of Metabolism?

Answer 2

Catabolism & Anabolism

Question 3

What is Catabolism?

Answer 3

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

Question 4

What is Anabolism?

Answer 4

SYNTHESIS of new molecules from less complex components

Question 5

Why is it important to study metabolism?

Answer 5

1. Many diseases are due to metabolic issues like diabetes and galls stones.
2. By understanding how the normal body deals with nutrients we can better understand the disease as the body in the diseased state changes the way it uses the food. This aids in DIAGNOSING diseases and TREATMENT

Question 6

Why should metabolism be viewed as an integrated whole?

Answer 6

Usually the PRODUCT of one pathway is the SUBSTRATE of another

Question 7

What is ATP?

Answer 7

Adenosine Triphosphate

Short term energy reservoir
Can act as an acceptor and donor of energy

Adenine base + Ribose + 3 Phosphate Groups

Question 8

About how much ATP does the body have? Is it enough?

Answer 8

It only has 100g.
When used, it must be resynthesized through oxidative phosphorylation in the mitochondria

Exercise uses 500g per minute
At rest, 40 Kg per DAY

Question 9

What are the 4 major oxidative pathways?

Answer 9

1. Glycolysis
2. Citric Acid Cycle
3. Electron Transport Chain
4. Fatty Acid Oxidation

Question 10

Illustrate and explain the process of Glycolysis

including production of Lactate and Acetlyl CoA

Answer 10

https://www.unm.edu/~lkravitz/MEDIA2/GLY1aa.gif

Question 11

What occurs during phosphorylation in glycolysis?

Answer 11

A hexose sugar (glucose) is phosphorylated by two molecules of ATP to form hexose bisphosphate.

The molecules becomes less stable and more reaction preventing it from diffusing out of the cell.

Question 12

What happens during lysis in glycolysis?

Answer 12

The hexose bisphosphate is split into 2 triose phosphates

Question 13

What happens during oxidation in glycolysis?

Answer 13

Hydrogen atoms are removed from each of the triose phophates and it reduces NAD+ to NADH

Due to this, a total of 2 NADH are produced

Question 14

What happens during ATP formation in glycolysis?

Answer 14

Substrate level phophorylation occurs to directly produce 4 molecules of ATP (2 are used in Glucose to Fructose 1,6 bisphosphate = net +2 ATP)

Question 15

What happens during ATP formation in glycolysis?

Answer 15

Substrate level phophorylation occurs to directly produce 4 molecules of ATP (2 are used in Glucose to Fructose 1,6 bisphosphate = net +2 ATP)

Question 16

How can Glycolysis be regulated?

Answer 16

It can be regulated by:
reversible binding of allosteric effectors,
covalent modification,
transcription

Enzymes that catalyze irreversible reactions are potential sites for regulation.

Question 17

What are the 3 enzymes (kinases) that regulate glycolysis?

Answer 17

Hexokinase
Phosphofructokinase
Pyruvate Kinase

Question 18

What is hexokinase regulated by?

Answer 18

The amount of Glucose 6 Phosphate (G6P).
Build up of G6P causes the step before that:
(Glucose –> G6P) to seize

Question 19

What inhibits Phosphofructokinase?

Answer 19

1. ATP (when cell has enough ATP, production of hexose bisphosphate stops)
2. Citrate (product of the Citric Acid Cycle… Increase of citrate stop it)
3. H + ions too (increased H+ decreases pH…. causes it to stop)

Question 20

What stimulates Phosphofructokinase?

Answer 20

AMP 
(generated by metabolism of ADP)
ADP generated by hydrolysis of ATP
ADP + ADP --> ATP + AMP
Uses Adenylate Kinase

Question 21

How is regulation of glycolysis different in the Liver?

Answer 21

1. PFK inhibited by HIGH conc. of ATP and citrate
2. PFK stimulated indirectly by build up of F6P (fructose phosphate)
3. Unlike hexokinase, Glucokinase is not inhibited by G6P

Question 22

What 2 kinases in the liver are involved in regulating glycolysis?

Answer 22

Hexokinase and Glucokinase

Question 23

What do tumours and exercising muscles have in common?

Answer 23

They generate large amounts of ATP through anaerobic respiration.

Question 24

Why does the body produce lactate in glycolysis in anaerobic respiration?

Answer 24

NAD+ is required for second part of glycolysis to continue to make pyruvate from hexose bisphosphate. To produce lactate, NADH is metabolized to produce NAD+ and it can return to where it is required.

Question 25

What are the consequences of producing lactate?

Answer 25

Lactate is acidic.
Accumulation of a lot of lactate inhibits Phosphofructokinase (PFK) in phosphorylation
(phosphorylation is required for starting glycolysis)

It can be overcome by the liver

Question 26

Why do tumours use glycolysis?

Answer 26

Tumours usually get nutrients from blood supply but the often outgrow the blood supply.
This causes the oxygen levels to decrease and create an environment of hypoxia.
This causes the cell metabolism to revert to glycolysis.
The hypoxia activates the transcription factor HIF-1
TF HIF-1 regulates the expression of specific enzymes in glycolysis
(Increase hexokinase and PFK expression)