Lipids, Ketone Bodies And B Oxidation

Question 1

How many classes of lipids are there?

Answer 1

3

Question 2

What are the 3 classes of lipids?

Answer 2

-Fatty acid derivatives
-Hydroxyl-methyl-glutamic acid derivatives (HMG acid derivatives)
-Fat soluble vitamins

Question 3

Give 2 examples of fatty acid derivatives and what there function is:

Answer 3

Fatty acids - Fuel molecules
Triacylglycerols - Fuel storage and insulation

Question 4

Give 2 examples of Hydroxyl-methyl-glutamic (HMG) acid derivatives

Answer 4

Ketone bodies - Water soluble fuel molecules
Cholesterol - steroid hormone synthesis and regulate membrane fluidity
Cholesterol esters- cholesterol storage

Question 5

What are the 4 lipid soluble vitamins?

Answer 5

A,D,E and K

Question 6

What is the difference in energy stores between a healthy individual and an obese individual?

Answer 6

Glycogen and muscle protein energy stores remain the same
Triacylglycerols are a lot higher in Obese individual

Question 7

How are TAGs stored?

Answer 7

They are hydrophobic so are stored in an anhydrous form in adipose tissue

Question 8

What is esterification?

Answer 8

When fatty acids are added to glycerol to form a Triacylglycerol

Question 9

What is the opposite of esterification?

Answer 9

Lipolysis

Question 10

What needs to happen to TAG that has been obtained from the diet so it can be metabolised to release energy?

Answer 10

Needs to be broken down into Fatty acids and glycerol

Question 11

What breaks down dietary lipids into fatty acids and glycerol and where does this take place?

Answer 11

Pancreatic lipases
Extracellularly in the small intestine (GI tract)

Question 12

What happens to the fatty acids once they have been taken up by the cells in the GI tract?

Answer 12

Converted back into TAGs and packaged into lipoprotein particles

Question 13

What is the name of the lipoprotein particle which transports dietary TAG from the small intestines to adipose tissue?

Answer 13

Chylomicrons

Question 14

How do Chylomicrons containing TAG get carried to adipose tissue?

Answer 14

Through the lymphatic system

Question 15

What is the name given to the milky looking lymph fluid containing lots of Chylomicrons containing TAG?

Answer 15

Chyle

Question 16

How are fatty acids transported in the blood once they are required?

Answer 16

Attached to albumin
Albumin-fatty acid complex

Question 17

Fatty acids undergo Beta Oxidation to release energy, generally what are the 3 key steps to fatty acid metabolism to release energy?

Answer 17

Activation
Transport
Beta oxidation

Question 18

Where does Fatty acid activation take place?

Answer 18

Outside the mitochondria

Question 19

How is a fatty acid activated?

Answer 19

Gets Linked to CoA

Question 20

Where do activated fatty acids get transported to?

Answer 20

Through the inner mitochondrial membrane into the mitochondria

Question 21

What transports activated fatty acids (fatty acyl CoA) into the mitochondria?

Answer 21

The Carnitine shuttle

Question 22

What enzyme catalyses the formation of activated fatty acids?

Answer 22

Fatty acyl CoA synthase

Question 23

What is an activated fatty acid actually called?

Answer 23

Fatty acyl CoA

Question 24

What occurs in Beta oxidation?

Answer 24

The fatty acyl CoA (activated fatty acid) has a 2 carbons removed evey cycle and forms NADH and FADH2

Question 25

Generally, what is B Oxidation of an activated fatty acid producing and why is this useful?

Answer 25

Acetyl CoA Reducing power (NADH and FADH2) Acetyl CoA can enter into the Krebs cycle and the reducing powe (NADH and FADH2) can be used in oxidative phosphorylation

Question 26

Where can B oxidation of fatty acids not take place and why?

Answer 26

Brain- Fatty acids can’t cross blood brain barrier RBC-Don’t have mitochondria

Question 27

Why does B oxidation of fatty acids need oxygen to take place?

Answer 27

Needed to regenerate NAD+ and FAD in oxidative phosphorylation

Question 28

What is the rate of FA oxidation regulated by?

Answer 28

AMP Insulin

Question 29

Where is glycerol transported to to be metabolised?

Answer 29

Liver

Question 30

What happens to glycerol in the liver?

Answer 30

It is phosphorylated into Glycerol phosphate

Question 31

What key enzyme Phosphorylates glycerol into glycerol phosphate in the liver?

Answer 31

Glycerol kinase

Question 32

What are the 2 fates of glycerol phosphate?

Answer 32

Converted into Triacylglycerols for storage Or converted into other intermediates so it can enter glycolysis

Question 33

What is glycerol phosphate converted into if it’s destined for glycolysis?

Answer 33

Dihydroxyacetone-P DHAP

Question 34

What is DHAP (Dihydroxyacetone-P) converted into so it is actually in Glycolysis?

Answer 34

Glyceraldehyde 3-P

Question 35

Describe how glycerol enters into glycolysis to be metabolised to release energy

Answer 35

Glycerol converted to glycerol phosphate by glycerol kinase in liver Glycerol phosphate converted into Dihydroxyacetone-P (DHAP) Dihydroxyacetone converted into Glyceraldehyde 3-P Glyceraldehyde 3-P is a metabolite in glycolysis

Question 36

Where are ketone bodies produced?

Answer 36

In the liver

Question 37

What are ketone bodies produced from?

Answer 37

Acetyl CoA

Question 38

When are ketone bodies produced?

Answer 38

When Acetyl CoA is in excess: -uncontrolled lipolysis or when lipolysis is high -during fasting and starvation (fatty acids released from adipose tissue to be used as energy source)

Question 39

How are ketone bodies formed from acetyl CoA? Step 1

Answer 39

Acetyl CoA converted into HMG CoA by HMG-CoA synthase enzyme

Question 40

How are ketone bodies produced from acetyl CoA? Step 2

Answer 40

HMG CoA lyase converts HMG-CoA into the ketone body acetoacetate From here acetoacetate can be converted into 2 other ketone bodies

Question 41

What are the 3 ketone bodies?

Answer 41

Acetoacetate Acetone B-hydroxybutyrate

Question 42

What hormones regulate the synthesis of Ketone bodies?

Answer 42

Insulin and glucagon

Question 43

What occurs when the insulin:glucagon ratio is high in relation to ketone body synthesis?

Answer 43

Enzyme HMG CoA REDUCTASE is activated and HMG CoA Lyase is inhibited so less ketone bodies made

Question 44

What happens when HMG CoA REDUCTASE is activated?

Answer 44

Cholesterol is synthesised

Question 45

What drug can decrease cholesterol levels and how does it do this?

Answer 45

Statins They inhibit the enzyme HMG CoA REDUCTASE so HMG CoA can’t be converted into cholesterol

Question 46

What happens when the insulin:glucagon ratio is low in relation to ketone body synthesis?

Answer 46

HMG CoA REDUCTASE inhibited HMG CoA lyases stimulated Ketone bodies synthesised

Question 47

So what does it mean when insulin is high? What does it mean when glucagon is high? In terms of cholesterol and ketone production:

Answer 47

High insulin = fed, cholesterol is synthesised High glucagon = starving, ketone bodies synthesised

Question 48

What is the benefit of producing ketone bodies?

Answer 48

Helps spare glucose in early starvation

Question 49

Why are ketone bodies dangerous?

Answer 49

They build up in the blood in Type 1 diabetes and cause diabetic ketoacidosis which is very dangerous