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 alpha 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 fatty acids 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 are the dietary lipids?

A

Phospholipids, triglycerides, cholesterol cholesterol ester, free fatty acids

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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 on

Forms mixed micelles

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24
Q

'’What physical mechanism helps with protein digestion?

A

Peristalsis

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25
What are bile salts derivatives of
Cholesterol
26
What are micelles?
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
What is the effect of pancreatic lipase on triacylglycerol?
It is degraded to monoacylglycerol and two fatty acids
28
What are the products of digestion of a cholesterol ester?
Cholesterol and free fatty acids
29
What are phospholipids hydrolysed to?
Fatty acid and a lysophospholipid
30
What is an enterocyte?
A cell of the intestinal lining
31
What does the products of lipid digestion form?
Mixed micelles with bile salts
32
What type of fatty acids do not require micelles for absorption?
Short and medium chain?
33
What is steatorrhea?
Lipid malabsorption (fatty stools)
34
Why might someone get steatorrhea?
Defects in bile secretion (gall bladder removal), pancreatic function or intestinal cell uptake
35
What effect does steatorrhea have on poo?
FLOAT! and they are oily an smelly
36
What happens to absorbed dietary lipids?
Intestinal cells resynthesize them for export
37
What are the lipids packaged with?
apoB-48 which is a solubalising protein
38
What are the lipids packaged into after absorption?
Chlyomicrons
39
What happens to the chlyomicrons?
They are released into the lymph by exocytosis and then blood
40
When the chlyomicron reaches the tissue, what happens to the triacylglyceride in a chlyomicron?
It is hydrolysed to fatty acid and glycerol by lipoprotein lipase
41
Where is lipoprotein lipase found?
capillaries of skeletal muscles and adipose tissue
42
What happens to the fatty acids produced by break down of triacylglycerol by lipoprotein lipase?
Used for energy or re-esterified to TAG for storgage
43
What are chlyomicrons depleted of TAG called?
Chlyomicron remnants - they go to the liver
44
What does the liver use glycerol for?
produces glycerol 3 phosphate, used in glycolysis and glucogenesis
45
How are triacylglycerols stored in adipose cells?
Stored as droplets that constitute the depot fat
46
What is the most efficient storage form of fuel?
triacylglycerols
47
What releases the fatty acids from stored TAG?
HSL, hormone sensitive lipase
48
What activates HSL?
Phosphorylation in response to epinephrine
49
What might promote dephosphorylation (deactivation) of lipase?
High plasma glucose and insulin
50
What does free fatty acid complex with in order to be transported through the blood?
Serum albumin
51
What is the most abundant plasma protein?
Serum albumen
52
What are esterified-fatty acid carried by in the blood?
Lipoproteins
53
What cannot be transported in the blood or lymph as free molecules?
TAGs cholesterol esters
54
What makes up the hydrophobic core of a lipoprotein?
TAGs, cholesterol esters
55
What makes up the hydrophilic surfaces of a lipoprotein?
Unesterified cholesterol, phospholipids apiloproteins -B100 eg
56
Which type of lipoproteins are rich in TAG?
Chlyomicrons and VLDL
57
Which type of lipoproteins are rich in Cholesterol?
HDL, LDL
58
Which type of lipoproteins are rich in proteins?
HDL
59
Where do chlyomicrons transport TAG?
Intestine to tissues
60
Where do VLDL transport TAG?
Liver to tissue
61
Where do LDL transport cholesterol?
Extrahepatic tissue
62
Where do HDL transport cholesterol?
Tissue to liver for elimination
63
What is the effect of too much LDL?
Atherosclerosis - lipid develops into fatty streaks and plaque within the artery.
64
Pair lipid classes with their functions Fatty acids Triglyceride Phospholipid Glycolipid Steroids • Energy storage • Membrane structure • Enzyme cofactors • Steroid hormones • Vitamin A, D, E, K • Signalling molecuels
Fatty acids - Energy storage Triglyceride - Energy storage Phospholipid - Membrane structure, transport for Vitamin A, D, E, K Glycolipid - membrane component, signalling Steroids - Steroid hormones, signalling
64
Describe the general structure of the lipid classes Fatty acids Triacylglycerol Phospholipid Glycolipid Steroids
65
Describe the structure of 18:1(9) (fatty acid)
18 carbons long with one double bond at carbon 9
66
What are the functions of a phospholipid?
Cell membranes, lipid transport, allow signalling molecules to attach
67
What are the 3 main steroid classes?
1. Cholesterol 2. Steroid hormones 3. Bile salts
68
Where is cholesterol aquired from?
Liver - synthesis cholesterol Diet - Animal products
69
How do statins lower cholesterol
Lower LDL levels Inhibition in Cholesterol synthesis
70
What is the function of Eicosanoids?
Locally signalling lipids, have a very short half life and are regulated messengers
71
What systems do eicosanoids help regulate?
Immune system - Inflammatory response Immune and blood system - Blood pressure and platelet levels Reproductive system - sperm mobility
72
How are lipid products digested by small intestine wall (enterocytes)?
Diffusion through membrane, lipids released by mixed micelles
73
How are esterified
74
How are Triglycerides carried in the blood?
Lipoproteins
75
Which lipoproteins carry cholesterol in the blood?
LDL - to Tissue HDL - to liver from tissue