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LIpids Flashcards

1
Q

Which Vitamin is not derived from a lipid?

A

Vitamin C

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2
Q

Describe fatty acids

A

They have polar heads and fatty acids chain tail

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3
Q

Describe Triacylglycerides

A

esters of glycerol and 3 FA

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4
Q

Describe a phospholipid

A

Polar phosphate head and non-polar lipid tail

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5
Q

What is mainly composed of phospholipids?

A

The cell membrane

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6
Q

Describe a glycolipid

A

A lipid with a carbohydrate attached

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7
Q

Describe a steroid

A

Ring like structure

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8
Q

What are unsaturated FA?

A

When there is one or more double bonds meaning they cannot stack correctly and have low mp due to weak intermolecular forces

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9
Q

What are saturated FA?

A

When there are no C=C double bonds meaning they have a high mp due to strong intermolecular forces between them

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10
Q

If a FA had 18 carbon atoms and 0 double bonds what would be its nomenclature?

A

18:0

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11
Q

What is the nomenclature of lipids?

A

Ratio of Carbons:C=C double bonds

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12
Q

What is a good fatty acid?

A

One that is high in polyunsaturated

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13
Q

What is a bad fatty acid?

A

One that is high in saturated fatty acids (clogs up arteries)

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14
Q

What is a very bad fatty acid?

A

A trans fatty acid - one that comes from the hydrogenation of vegetable oils

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15
Q

What is an essential fatty acid?

A

One that cannot be synthesised by the body so must be obtained from our diets

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16
Q

Beyond what double bond can human not introduce beyond?

A

Carbon 9

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17
Q

is TAG charged?

A

No - its is neutral

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18
Q

What is the main dietary lipid?

A

TAG

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19
Q

What is the lipid used for insulation?

A

TAG

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20
Q

What is omega 3 derived from?

A

Linolenic Acid

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21
Q

How many FA groups do phospholipids have?

A

2

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22
Q

Why is a phospholipid known as amphipathic?

A

Because it has both a polar and non-polar part

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23
Q

What are phospholipids a component of?

A

The plasma membrane

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24
Q

Where is the main site of lipid digestion?

A

Small intestine

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25
What enzyme breaks down lipids?
Pancreatic lipase
26
What do bile salts do to lipids?
Act as a detergent forming emulsions
27
What does lipase break TAG down to?
Monoacylglycerol and 2FA
28
What can cross the microvilli?
Short and medium FA
29
What is steatorrhea?
Lipid malabsorption
30
What is steatorrhea cause by?
Defects in bile, pancreatic or intestinal function
31
What does steatorrhea cause?
Excess fat in faeces
32
Once the FA have been absorbed the the small intestine what happens?
They are resynthesised back to TAG
33
What are lipids transported in the blood in?
Chylomicrons
34
Where are chylomicrons released?
Into lymph then into the blood stream
35
Why does bile break down larger fats?
To make smaller fragments | Create a larger surface area for lipase enzymes
36
What happens in the chylomicrons?
TAG is hydrolysed to FA and glycerol
37
What enzyme hydrolyses TAG in the chylomicrons?
Lipoprotein lipase
38
Where do the remnants of the chylomicrons go?
To the liver
39
Where does the glycerol eventually go?
Back to the liver to be converted to G-3-P
40
What is the nature of the core of a lipoprotein?
Hydrophobic
41
What is the nature of the surface of a lipoprotein?
Hydrophilic
42
What does HDL do?
Transports cholesterol from tissues to liver
43
What does LDL do?
Transports cholesterol from liver to tissues
44
What do chylomicrons do?
Transport TAG from intestine to tissue
45
What does VLDL do?
Transport TAG from liver to tissue
46
Can unlimited LDL be taken up by tissues?
No only a certain amount can
47
What can too much LDL cause?
Athersclerosis
48
How does too much LDL cause atherosclerosis?
It wont be taken up by cells Is deposited in vessels Forms plaques
49
What are the 3 stages of beta oxidation?
Activation Transport Degradation
50
Where are FA in beta oxidation activated?
In the cytosol
51
What are fatty acids activated to form?
Acyl CoA
52
Why can't Acyl CoA just enter the mitochondria?
Too big
53
How does Acyl CoA enter the mitochondria?
Carnitine shuttle
54
Describe the carnitine shuttle
``` Acyl CoA replaces CoA with carnitine Becomes Acyl carnitine Acyl carnitine can enter the mitochondrial matrix Converted back to Acyl CoA Carnitine leaves the matrix ```
55
What can inhibit the carnitine shuttle?
Malonyl CoA
56
How many steps does degradation of B oxidation occur in?
4
57
What are the 4 steps of degradation in B oxidation?
Dehydrogenation Hydration Dehydrogenation Thiolysis
58
What does the 1st dehydrogenation of degradation produce?
FADH2
59
What does the 2nd (but 3rd step of degradation) dehydrogenation produce?
NADH
60
What is produced in the 4th step of degradation in B oxidation?
Acetyl CoA
61
How many ATP is formed from B oxidation?
15 ATP
62
Where does the Acetyl CoA from B oxidation enter?
The CAC
63
Why can the Acetyl CoA form beta oxidation not be converted back to glucose?
Because of the irreversible pyruvate to acetyl CoA step
64
What forms ketone bodies?
Excess Acetyl CoA
65
How many Acetyl CoA combine to form Ketone bodies?
2
66
What does the brain use as a source of energy?
Ketone bodies
67
Where uses ketone bodies as an energy source?
Skeletal muscle Cardiac muscle Brian
68
Where are ketones formed?
In the liver
69
Where can ketones not be used as an energy source?
The liver
70
What does excess ketones do to blood pH?
Drops the pH as it is acidic | Can lead to coma then death
71
What is the effect of diabetes ketosis?
Cells really need glucose Breakdown fats Causes an excess of acetyl CoA Causes an excess of ketones
72
Where does FA synthesis occur?
Liver Lactating mammary gland Adipose Tissue
73
Where do we get our FA?
From our diet | From synthesis of excess carbohydrates and protein
74
Where is acetyl CoA formed?
Mitochondria
75
Where are FA formed?
Cytosol
76
How is Acetyl CoA shuffled into the cytosol?
Using the citrate shuttle
77
What enzymes are required for FA synthesis?
Acetyl CoA carboxylase | Fatty Acid Synthase
78
When does the citrate shuttle work?
When Citrate conc. is high | Meaning no more Acetyl CoA is needed
79
What enzyme is needed to form malonyl CoA?
Acetyl CoA carboxylase
80
What is the committed step in the synthesis of FA?
The formation of Malonyl CoA
81
Malonyl CoA stops.... but is needed for....?
Stop degradation | But is needed for synthesis
82
What activates Acetyl CoA carboxylase?
High conc. of citrate | Insulin
83
What deactivates acetyl CoA carboxylase?
High conc. of palmitoyl CoA (the end product) | Glucagon, epinephrine
84
Why does glucagon and epinephrine inhibit acetyl CoA carboxylase?
Suggests the body is quickly needing energy- doesn't want to waste energy synthesising FA
85
What is the first reaction in FA synthesis?
Elongation
86
What are the 3 opposite reaction from FA degradation in FA synthesis?
Reduction Dehydration Reduction
87
What is used instead of NADH in FA synthesis?
NADPH
88
How many times is the elongation cycle repeated?
6 more times
89
What is the end product of the elongation cycle?
Palmityl-ACP
90
What happens after the elongation cycle?
The palmityl CoA is cleaved from the ACP
91
Where does the ACP come into play?
The intermediates in FA synthesis are covalently linked to this protein
92
How many enzymes is fatty acid synthase composed of?
7
93
What is fatty acid synthase the enzyme a good example of?
Quaternary structure
94
Where does most of the NADPH for FA synthesis come from?
The pentose phosphate pathway
95
Why do FA synthesis and degradation not run at the same time?
Why create something to just destroy it again
96
What is cholesterol?
The starting material for the synthesis of steroid hormones
97
How many carbons are eicosanoids derived from?
20
98
What is cholesterol a component of?
The cell membrane
99
Where is cholesterol synthesised mainly?
In the liver
100
How do statins work?
They interfere with the reductase enzyme to stop cholesterol being made
101
What do statins lower?
LDL levels | Risk of developing atherosclerosis
102
What are eicosanoids precursors for?
Prostaglandins Thromboxanes Leukotrienes
103
What is cholesterol a precursor for?
Steroids
104
What cleaves the ACP from the Palmityl CoA?
Thioesterase
105
Where does most of the NADP for the synthesis of Palmitoyl-coA come from?
Pentose phosphate pathway
106
What is a storage fate after the synthesis of FA?
Storage

Science for Medicine (13 decks)

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