Lipids 1 Flashcards

1
Q

Where are the different places you can find lipids in the body?

A

Cell membranes, lipid droplets in adipose tissue, in blood lipoproteins

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2
Q

What are some of the biological functions of lipids?

A

Stored form of energy, structural element of membranes, enzyme cofactors, hormones, vitamins A,D,EK, signalling molecules

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3
Q

What are the different classes of lipids?

A

Fatty acids, triacylglycerol, phospholipids, glycolipid and steroids

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4
Q

When writing the structure of a fatty acid, what does the term 18:2(9,12) mean?

A

There are 18 carbons with two double bonds, occuring at carbon atoms 9 and 12

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5
Q

What are the essential fatty acids?

A

Linoleic and aplha - linolenic - must get these from plants

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6
Q

What are good fats?

A

High in polyunsaturated fatty acids e.g vegetable oil, sunflower oil and olive oil

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7
Q

What are the bad fats?

A

High in saturated fatty acids? e.g. stearic (beef)

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8
Q

What useful function do saturated fatty acids have?

A

Huge role in myelination of nerve fibres and hormone production

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9
Q

What are the really bad fats?

A

Trans fatty acids

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10
Q

How are these really bad fats made?

A

Hydrogenation of vegetable oils

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11
Q

Up to which point in a fatty acid chain can a human no longer produce a double bond?

A

9

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12
Q

What can be derived from linolenic acid?

A

Omega three fatty acids

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13
Q

What effect does omega 3 have?

A

lowers plasma cholesterol prevents atherosclerosis, lowers triacylglycerol

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14
Q

What is derived from linoleic acid?

A

Omega 6

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15
Q

What are the effects of fatty acid deficiency?

A

Growth retardation, reproductive failure, skin lesions, ADHD - more behavioural problems Depression

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16
Q

How would you describe the Ph and charge of an ester?

A

Neutral and uncharged

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17
Q

Describe the solubility of triacylglycerol

A

Insoluble in water

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18
Q

What is the main lipid component of adipose tissue?

A

Lipid droplets

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19
Q

What can triacylglycerol be used for?

A

Fuel and insulation

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20
Q

What is the main dietary lipid?

A

Triacylglycerol

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21
Q

What is the main site of lipid digestion?

A

Small intestine

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22
Q

Lipases are involved in lipid digestion, where are lipases made?

A

Pancreas

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23
Q

What effect does bile salts have?

A

Emulsification of lipids (breaks down fat globules into smaller droplets) - larger surface area for lipase to act onForms mixed micelles

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24
Q

What physical mechanism helps with protein digestion?

A

Peristalsis

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25
Q

What are bile salts derivatives of

A

Cholesterol

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26
Q

What are micelles?

A

The end product of fat digestion is converted into these - They are small water soluble droplets. They are closed lipid monolayers with a fatty acid core and a polar surface

27
Q

What is the effect of pancreatic lipase on triacylglycerol?

A

It is degraded to monoacylglycerol and two fatty acids

28
Q

What are the products of digestion of a cholesterol ester?

A

Cholesterol and free fatty acids

29
Q

What are phospholipids hydrolysed to?

A

Fatty acid and a lysophospholipid

30
Q

What is an enterocyte?

A

A cell of the intestinal lining

31
Q

What does the products of lipid digestion form?

A

Mixed micelles with bile salts

32
Q

What type of fatty acids do not require micelles for absorption?

A

Short and medium chain?

33
Q

What is steatorrhea?

A

Lipid malabsorption

34
Q

Why might someone get steatorrhea?

A

Defects in bile secretion (gall bladder removal), pancreatic function or intestinal cell uptake

35
Q

What effect does steatorrhea have on poo?

A

FLOAT! and they are oily an smelly

36
Q

What happens to absorbed dietary lipids?

A

Intestinal cells resynthesize them for export

37
Q

What are the lipids packaged with?

A

apoB-48 which is a solubalising protein

38
Q

What are the lipids packaged into after absorption?

A

Chlyomicrons

39
Q

What happens to the chlyomicrons?

A

They are released into the lymph by exocytosis and then blood

40
Q

When the chlyomicron reaches the tissue, what happens to the triacylglyceride in a chlyomicron?

A

It is hydrolysed to fatty acid and glycerol by lipoprotein lipase

41
Q

Where is lipoprotein lipase found?

A

capillaries of skeletal muscles and adipose tissue

42
Q

What happens to the fatty acids produced by break down of triacylglycerol by lipoprotein lipase?

A

Used for energy or re-esterified to TAG for storgage

43
Q

What are chlyomicrons depleted of TAG called?

A

Chlyomicron remnants - they go to the liver

44
Q

What does the liver use glycerol for?

A

produces glycerol 3 phosphate, used in glycolysis and glucogenesis

45
Q

How are triacylglycerols stored in adipose cells?

A

Stored as droplets that constitute the depot fat

46
Q

What is the most efficient storage form of fuel?

A

triacylglycerols

47
Q

What releases the fatty acids from stored TAG?

A

HSL, hormone sensitive lipase

48
Q

What activates HSL?

A

Phosphorylation in response to epinephrine

49
Q

What might promote dephosphorylation (deactivation) of lipase?

A

High plasma glucose and insulin

50
Q

What does free fatty acid complex with in order to be transported through the blood?

A

Serum albumin

51
Q

What is the most abundant plasma protein?

A

Serum albumen

52
Q

What is the fatty acid- serum albumen complex carried by?

A

Lipoproteins

53
Q

What cannot be transported in the blood or lymph as free molecules?

A

TAGs cholesterol esters

54
Q

What makes up the hydrophobic core of a lipoprotein?

A

TAGs, cholesterol esters

55
Q

What makes up the hydrophilic surfaces of a lipoprotein?

A

Unesterified cholesterol, phospholipids apiloproteins -B100 eg

56
Q

What is the order of lipoproteins in order of increasing density?

A

Chlyomicrons, VLDL, LDL HDL

57
Q

Which type of lipoproteins are rich in TAG?

A

Chlyomicrons and VLDL

58
Q

Which type of lipoproteins are rich in Cholesterol?

A

HDL, LDL

59
Q

Which type of lipoproteins are rich in proteins?

A

HDL

60
Q

Where do chlyomicrons transport TAG?

A

Intestine to tissues

61
Q

Where do VLDL transport TAG?

A

Liver to tissue

62
Q

Where do LDL transport cholesterol?

A

Extrahepatic tissue

63
Q

Where do HDL transport cholesterol?

A

Tissue to liver for elimination

64
Q

What is the effect of too much LDL?

A

Atherosclerosis - lipid develops into fatty streaks and plaque within the artery.