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MEH > Lipids, Ketone Bodies And B Oxidation > Flashcards

Lipids, Ketone Bodies And B Oxidation Flashcards

1
Q

How many classes of lipids are there?

A

3

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2
Q

What are the 3 classes of lipids?

A

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

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3
Q

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

A

Fatty acids - Fuel molecules
Triacylglycerols - Fuel storage and insulation

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4
Q

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

A

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

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5
Q

What are the 4 lipid soluble vitamins?

A

A,D,E and K

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6
Q

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

A

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

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7
Q

How are TAGs stored?

A

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

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8
Q

What is esterification?

A

When fatty acids are added to glycerol to form a Triacylglycerol

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9
Q

What is the opposite of esterification?

A

Lipolysis

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10
Q

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

A

Needs to be broken down into Fatty acids and glycerol

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11
Q

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

A

Pancreatic lipases
Extracellularly in the small intestine (GI tract)

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12
Q

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

A

Converted back into TAGs and packaged into lipoprotein particles

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13
Q

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

A

Chylomicrons

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14
Q

How do Chylomicrons containing TAG get carried to adipose tissue?

A

Through the lymphatic system

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15
Q

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

A

Chyle

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16
Q

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

A

Attached to albumin
Albumin-fatty acid complex

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17
Q

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

A

Activation
Transport
Beta oxidation

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18
Q

Where does Fatty acid activation take place?

A

Outside the mitochondria

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19
Q

How is a fatty acid activated?

A

Gets Linked to CoA

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20
Q

Where do activated fatty acids get transported to?

A

Through the inner mitochondrial membrane into the mitochondria

21
Q

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

A

The Carnitine shuttle

22
Q

What enzyme catalyses the formation of activated fatty acids?

A

Fatty acyl CoA synthase

23
Q

What is an activated fatty acid actually called?

A

Fatty acyl CoA

24
Q

What occurs in Beta oxidation?

A

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

25
Q

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

A

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

26
Q

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

A

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

27
Q

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

A

Needed to regenerate NAD+ and FAD in oxidative phosphorylation

28
Q

What is the rate of FA oxidation regulated by?

A

AMP
Insulin

29
Q

Where is glycerol transported to to be metabolised?

A

Liver

30
Q

What happens to glycerol in the liver?

A

It is phosphorylated into Glycerol phosphate

31
Q

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

A

Glycerol kinase

32
Q

What are the 2 fates of glycerol phosphate?

A

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

33
Q

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

A

Dihydroxyacetone-P DHAP

34
Q

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

A

Glyceraldehyde 3-P

35
Q

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

A

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

36
Q

Where are ketone bodies produced?

A

In the liver

37
Q

What are ketone bodies produced from?

A

Acetyl CoA

38
Q

When are ketone bodies produced?

A

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)

39
Q

How are ketone bodies formed from acetyl CoA?
Step 1

A

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

40
Q

How are ketone bodies produced from acetyl CoA?
Step 2

A

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

41
Q

What are the 3 ketone bodies?

A

Acetoacetate
Acetone
B-hydroxybutyrate

42
Q

What hormones regulate the synthesis of Ketone bodies?

A

Insulin and glucagon

43
Q

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

A

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

44
Q

What happens when HMG CoA REDUCTASE is activated?

A

Cholesterol is synthesised

45
Q

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

A

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

46
Q

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

A

HMG CoA REDUCTASE inhibited
HMG CoA lyases stimulated

Ketone bodies synthesised

47
Q

So what does it mean when insulin is high?
What does it mean when glucagon is high?

In terms of cholesterol and ketone production:

A

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

48
Q

What is the benefit of producing ketone bodies?

A

Helps spare glucose in early starvation

49
Q

Why are ketone bodies dangerous?

A

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

MEH (33 decks)

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