Metabolic Stores

Question 1

Where is glycogen stored?

Answer 1

Mainly in liver and skeletal muscle

Question 2

Glycogen can cover energy needs for how long?

Answer 2

3-5 hours

Question 3

When glycogen is broken down what does it produce?

Answer 3

Glucose-6-Phosphate (cannot be transported across membranes)

Question 4

What major form of stored fuel is used by the body and why are these the major form?

Answer 4

Lipids

-Used as major form as the triglycerides/triacylglycerols can produce six times the amount of energy as glycogen

Question 5

What is the general structure of triglycerides

Answer 5

Esters of glycerol and fatty acids

Question 6

What is most of the fat in the body stored as?

Answer 6

Triglycerides

Question 7

What is the breakdown of fats called?

Answer 7

Lipolysis

Question 8

Describe the breakdown of triglycerides

Answer 8

Lipases digest triglycerides into glycerol and 3 fatty acids.

Question 9

How are fatty acids broken down and what do they form?

Answer 9

Broken down via beta oxidation forming a two carbon acyl unit that combines with Coenzyme A to form Acetyl-Coenzyme A. Although no ATP is formed by this directly, the hydrogen ions and electrons removed by oxidation are passed to the electron transport chain

Question 10

Fatty acids and glycerol released by adipose tissue are metabolised where?

Answer 10

In the liver

Question 11

The break down of fatty acids occur when?

Answer 11

When other fuel sources are not available

Question 12

The breakdown of fatty acids eventually leads to the formation of what? and name some examples

Answer 12

Ketone bodies. Examples include; acetoacetate, 3-hyrdoxybutyrate and acetone

Question 13

Why do ketone bodies form?

Answer 13

Because the acetyl-CoA formed from the breakdown of fatty acids cannot enter the citric acid cycle since oxaloacetate becomes depleted as the liver converts it to pyruvate to form glucose

Question 14

What happens to unused amino acids

Answer 14

They are used as metabolic fuel because the cannot be stored

Question 15

What happens when amino acids are deaminated?

Answer 15

It produces NH4 and a keto acid which are intermediates of the glycolytic pathway or krebs cycle

Question 16

When amino acids cannot release their amino groups as NH4+, what do they do?

Answer 16

They pass their amino group to a keto acid in a process called transamination. This keto acid can then be fed into glycolysis/krebs cycle while the remaining amino acid can be deaminated and used similarly

Question 17

What is the feature of NH4+ that means it is disposed of quickly and how is this done?

Answer 17

The group is very toxic so the body very quickly turns it into urea

Question 18

What us Gluconeogenesis

Answer 18

The formation of glucose from non-carbohydrate sources

Question 19

What molecules are fed into gluconeogenesis

Answer 19

Glycerol from the triglycerates and the carbon back bone from amino acids

Question 20

Where does gluconeogenesis occur?

Answer 20

Mostly in the liver

Question 21

What is the most effective fuel?

Answer 21

Carbohydrates

Question 22

What fuel sources does the brain use?

Answer 22

Normally just glucose but in times of starvation it can use ketone bodies formed in other tissues

Question 23

Why cannot the brain use fatty acids as a fuel source?

Answer 23

Because they cannot pass the blood brain barrier

Question 24

Why does the brain require a constant supply of glucose/glycogen?

Answer 24

Because it cannot store glucose or glycogen

Question 25

What fuel can the skeletal muscle use?

Answer 25

Glucose, fatty acids and ketone bodies

Question 26

How much of the glycogen reserves are found in skeletal muscle/

Answer 26

3/4s so a very large amount

Question 27

When muscle protein is broken down what happens to the amino acids?

Answer 27

They pass their amino groups (transamination) to pyruvate to form alanine.