Week 10 - Energy and Metabolism

Question 1

Why do we need ATP

Answer 1

Contraction of muscle
Biosynthesis of many substances
Movement of ions
Generation of heat

Question 2

What is ATP made up of

Answer 2

Adenine
Ribose sugar
3 phosphate groups

Question 3

What type of reaction does ATP go through to produce ADP

Answer 3

hydrolysis (addition of water)

Question 4

3 food macromolecules

Answer 4

Carbohydrates, fats and proteins

Question 5

Where does glycolysis occur

Answer 5

Cytosol of all cells

Question 6

Does glycolysis require oxygen

Answer 6

No

Question 7

What are the products of glycolysis

Answer 7

2 ATP, 2 pyruvate and and 2 NADH

Question 8

What are the two phases of glycolysis

Answer 8

Initial investment phase

Energy payoff phase

Question 9

What is 6 carbon glucose broken down into

Answer 9

2x 3 carbon glyceraldehyde-3-phosphate

Question 10

Net gain of ATP in glycolysis

Answer 10

2 ATP

Question 11

What are the two 3-glyceraldehyde-3-phosphates converted to in the energy payoff phase

Answer 11

2x 3c-pyruvate

Question 12

What happens to pyruvate in the absence of oxygen

Answer 12

It is broken down into lactate by an enzyme called lactate dehydrogenase

Question 13

If oxygen is absent what product of anaerobic respiration is used to propagate glycolysis

Answer 13

NAD+ since it is used up in the energy payoff phase.

Question 14

What happens to pyruvate after glycolysis in the presence of oxygen

Answer 14

Pyruvate is transported to the mitochondrion and converted to acetyl coenzyme A by an enzyme called pyruvate dehydrogenase. 3c pyruvate loses a carbon to produce CO2 and NADH (which is fed to the electron transport chain.

Question 16

What are the two phases of the citric acid cycle

Answer 16

Decarboxylating and reductive

Question 17

What happens during the decarboxylating phase

Answer 17

6C citrate gets decarboxylated into 4C succinylcholine CoA, excess lost as CO2

Question 18

What happens during the reductive phase

Answer 18

4C succinyl coenzyme A is reduced to produce 4C oxaloacetate. 4C oxaloacetate joins acetyl coenzyme A and cycle starts over

Question 19

What is gained during the citric acid cycle

Answer 19

3NAD+ reduced to NADH

1FAD reduced to FADH2

Question 20

What happens during the electron transport chain

Answer 20

NADH enters electron transport chain at complex 1

Proton is pumped out by complex 1

Question 21

How is glucose stored in the body/liver/muscle

Answer 21

As glucose in the body and glycogen in the liver and muscle

Question 22

How long do glycogen stores last in the body if not eating

Answer 22

16-24 hours

Question 23

What happens when glycogen energy storage runs out

Answer 23

The body switches to lipid metabolism

Question 24

How are lipids stored in adipose tissue

Answer 24

As triglycerides

Question 25

What composes triglyceride

Answer 25

Glycerol
3 fatty acids

Question 26

What type of enzyme releases fatty acids and glycerol

Answer 26

Lipase

Question 27

When fatty acids are released from glycerol, what allows them to be transported in the blood

Answer 27

They attach to albumin

Question 28

Where do fatty acids go in order to be metabolised

Answer 28

They are taken up by cells, modified and then travel to the mitochondrial matrix and undergo beta-oxidation

Question 29

Describe the carnitine shuttle

Answer 29

Coenzyme A added by acetyl coenzyme A synthetase to produce fatty acyl CoA (can now pass through outer membrane. Uses ATP.

Coenzyme A is replaced with carnitine. Fatty acetyl carnitine is able to pass through inner membrane.

Once in matrix, carnitine is replaced with acetyl coenzyme A again in the matrix.

Question 30

Cleavage of fatty acids occurs through what process and what does it involve

Answer 30

Beta-oxidation - cleavage of every second covalent bond between carbons

Question 31

What happens during transamination

Answer 31

Amine group on the protein is removed

Amine group is donated to a-ketoglutamate (or similar)

Simultaneously, a-ketoglutamate donates ketone residue to the original amino acid forming a new ketoacid and a new amino acid (glutamate)

Question 32

What are the two possible methods of protein metabolism

Answer 32

Deamination and transamination

Question 33

What is deamination

Answer 33

Removal of amine group which takes place in the liver and causes the production of ammonium which is toxic

Ammonium is converted to urea

This releases carbon backbone of amino acid which can be regenerated into glucose, fatty acids or TCA cycle intermediates.