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Science for FUN > lipids > Flashcards

lipids Flashcards

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1
Q

what are some purposes of lipids?

A 
stored form of energy 
structural component of cell membranes
needed as enzyme cofactors
used in hormones 
used for synthesis of vitamins A, D, E and K
used as signalling molecules
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2
Q

what is the structure of a fatty acid?

A

hydrocarbon chains with a carboxylic acid at one end.

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3
Q

what are the two forms which a fatty acid can be present in?

A

saturated or unsaturated

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4
Q

what are essential fatty acids?

A

acids that must be obtained via our diets

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5
Q

what are triacylglycerides(TAGs) formed from?

A

esters of fatty acids and glycerol

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6
Q

what are some function of TAGs?

A

major component of adipose tissue

at as insulation and dietary fuel

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7
Q

what is the structure of phospholipids?

A

glycerol bonded to two fatty acids and a phosphate group

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8
Q

phospholipids are amphipathic; true or false?

A

true

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9
Q

where does most digestion of triacylglycerols take place?

A

small intestine

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10
Q

what mechanisms aid the digestion of TAGs in the small intestine?

A

pancreatic enzymes

emulsification by bile salts and peristalsis

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11
Q

what is most TAG digested to?

A

monoacylglycerol and two fatty acids

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12
Q

what are cholesterol esters broken down into?

A

cholesterol and a fatty acid

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13
Q

what are phospholipids broken down into?

A

hydrolysed to a fatty acid and lysophospholipid

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14
Q

what happens to the products of lipid digestion after they are digested?

A

they form mixed micelles with bile salts

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15
Q

what do mixed micelles do when they approach the brush border?

A

release their contents

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16
Q

what types of fatty acids would form mixed micelles?

A

long chain fatty acids

17
Q

how are lipids transported in the body?

A

TAG, fatty acids and cholesterol esters are repackaged into chylomicrons, which are released into the blood via the lymphatic system.

18
Q

what happens to chylomicrons when they reach tissues?

A

TAG is hydrolysed to fatty acids and glycerol by lipoprotein lipase.

19
Q

what is the purpose of the free fatty acids produced from TAG hydrolysation?

A

used for energy

re-esterified into TAG for storage

20
Q

how are free fatty acids transported?

A

lipoproteins, in a complex with serum albumin

21
Q

how are fats transported?

A

high and low density lipoproteins?

22
Q

what is the difference between high density and low density lipoproteins?

A

low density lipoproteins take cholesterol from the liver to other tissues
high density lipoproteins do the opposite, bring back cholesterol from the tissues to the liver for elimination

23
Q

how many carbons are degraded at a time in beta oxidation?

A

2

24
Q

what are the products of fatty acid metabolism via beta oxidation?

A

acetyl CoA
NADH
FADH2

25
Q

what are the 3 stages of beta oxidation?

A

activation
transport
degradation

26
Q

what happens in the activation stage?

A

fatty acids are activated to form fatty acyl CoA in the cytoplasm

27
Q

what happens in the transport stage?

A

carnitine shuttle transfers long chain fatty acyl CoA from the cytoplasm to the inside of the mitochondrion

28
Q

what inhibits carnitine fatty acyl transferase and why is this significant?

A

malonyl CoA, which is used in fatty acid synthesis, therefore, synthesis and degradation cannot occur simultaneously

29
Q

what happens in the degradation stage?

A

fatty acyl coA is dehydrogenated to form FADH2 and another intermediate.

30
Q

what happens to the intermediate that is not FADH2 that is produced in fatty acid degradation?

A

it is hydrated, then dehydrogenated again to form NADH

31
Q

what is the final step of fatty acid degradation?

A

thiolysis occurs, to form acetyl CoA that feeds into the CAC

32
Q

what are the products of beta oxidation?

A

1 acetyl CoA
1 NADH
1 FADH2
carbon species 2 carbons shorter than the original.

33
Q

what happens to acetyl CoA from fat metabolism when it is in excess?

A

forms ketone bodies

34
Q

what types of tissues can use ketone bodies as fuel sources?

A

cardiac and skeletal muscle

brain can utilise it in times of starvation

35
Q

where does ketogenesis occur?

A

liver

36
Q

what are the main ketone bodies?

A

acetoacetate and 3-hydroxybutarate

Science for FUN (8 decks)

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