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Drew 922 > Block 3 Lecture 2 -- Dietary Lipids > Flashcards

Block 3 Lecture 2 -- Dietary Lipids Flashcards

1
Q

How long are FAs/TGs?

A

3-20 C, usually 17 or 15

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2
Q

What is the most common saturated fatty acid?

A

stearic acid

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3
Q

What is the structure of stearic acid?

A

18:0

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4
Q

What are examples of unsaturated FAs?

A

1) oleic

2) linoleic

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5
Q

Oleic acid structure

A

18:1 ∆9

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6
Q

Linoleic acid structure

A

18:2 ∆9,12

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7
Q

What is the natural configuration for glycerophospholipids and sphingolipids?

A

(R)-L

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8
Q

Where is lecithin found?

A

naturally in egg yolk & soybean

also as food additive or dietary supplement

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9
Q

How is lecithin metabolized in the body?

A

lecithin –> GPC –> acetylcholine

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10
Q

What does GPC stand for and where can it be found?

A

glycerophosphorylcholine, milk

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11
Q

Why are sphingolipids more stable than glycerophospholipids?

A

presence of amide bonds

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12
Q

From what are eicosanoids produced?

A

multi-unsaturated C20 arachidonic acid

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13
Q

What is the structure of arachidonic acid?

A

20:4 ∆5,8,11,14

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14
Q

What enzyme converts arachidonic acid to PGs and TXs?

A

PGH2/COX

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15
Q

What structures does arachidonic acid produce?

A

PGs and thromboxanes

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16
Q

What are the functions of eicosanoids?

A

1) BP
2) smooth muscle contractoin
3) pain, fever
4) coag
5) reproduction
6) coagulation
7) bronchoconstriction
8) metabolism regulation

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17
Q

How is naproxen supplied?

A

(s) only

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18
Q

How is ibuprofen supplied?

A

racemic (converted to S in vivo)

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19
Q

What is the backbone for cholesterol?

A

tetracyclic C17 alkane

    • 3 6-membered rings
    • 1 5-membered ring
    • B/C and C/D are always transfused
    • methyls at A/B and C/D fusion points
    • R’s at C12 and end of side chain
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20
Q

For which structures do steroids serve as precursors?

A

1) Vit D3
2) steroid hormones
3) bile acids

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21
Q

Where is cholesterol important?

A

membranes, liver, skin

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22
Q

For bile acids, what are the possibilities for the 2 side chains?

A

1) H or OH

2) OH, HNCH2COOH, or HN(CH2)2SO3H

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23
Q

Describe the structure of a liposome?

A

stable bilayered vesicle, relatively large (several 100 A)

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24
Q

What do corticoids do?

A

downregulate proinflammatory cytokines

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25
What enzyme do the sex hormones need?
aromatase for aromatization of the A ring
26
What is cortisone's side chain?
acetone
27
What are the side chains for the androgens?
trans hydroxyl
28
What are the side chains of the fat-soluble vitamins?
all iso-prenoid derivatives
29
Where are TGs mainly digested?
in intestine by pancreatic lipase
30
What are the products of TG digestion?
2 FA + MAG
31
Describe the action of pancreatic lipase
operates at ph 6; hydrolyzes 1,3 FAs
32
Describe the function of colipase.
makes PL more active (binds fat and another lipase)
33
Describe the action of phospholipase
digests phospholipids
34
Where are shorter FAs digested?
hydrolyzed by mouth/stomach lipases
35
Where are bile acids re-absorbed?
ileum
36
Describe the structure of a micelle
small (10 - 100 A) lipid monolayer complexes
37
When are bile acids not required?
for small FAs (4-12 C MCTs)
38
How are TGs absorbed?
as 2 FA + 2-MAGs packaged into micelles with other lipids
39
What happens in TG absorption after micelle absorption?
epithelial cells resynthesize TGs in SER
40
what is the major apo-protein of chylomicrons?
B-48
41
What is the major apoprotein of VLDL?
B100
42
Where are apoproteins synthesized?
RER of hepatocytes
43
How are lipids packaged for blood transport?
into lipoproteins
44
Describe structure of lipoproteins.
aphipathic phospholipids on surface | cholesterol, ADEK in lumen
45
Where are lipoproteins assembled?
golgi
46
Why are ADEK not found in VLDL?
VLDL not from diet
47
How are lipoproteins secreted?
into lymph via exocytosis
48
What proteins are present in HDL that are transferred for development of mature chylomicrons?
ApoE and ApoCII
49
What is the function of ApoE?
allows rEcognition by tissue membrane receptors
50
What is the function of ApoCII
aCtivates LPL attached to glycoproteins of capillary epithelium
51
What does LPL do?
digests TGs to FAs and glycerol
52
What do the TGs resulting form LPL do?
1) taken up by adipose for storage | 2) minorly taken up by muscle for beta-oxidation
53
What happens to glycerol resulting from LPL?
to liver for recycling or gluconeogenesis
54
What happens to the chylomicron remnans from LPL?
recycle by liver 1) liver receptors recognize apoE 2) endocytosis then phagolysosome
55
What happens to VLDL
converted --> IDL --> LDL
56
What happens to LDL
cellular LDL receptors recognize apoB100 and trigger clarithin coated endocytosis
57
What is the function of adipose lipase?
releases FAs from adipose during fasting
58
How are FAs transported in the blood when released from adipose?
complex with albumin
59
What is Km?
the michaelis constant; the substrate concentration at which the reaction rate is 1/2 Vmax (inverse measure of affinity)
60
How do Adipose LPL and Muscle LPL compare?
adipose LPL has higher Km
61
When is ALPL hydrolysis preferable to MLPL?
only in fed state with high [CM]
62
What factors activate AL?
glucagon, epinephrine, norepi, corticoadrenals
63
What factors inhibit AL?
insulin
64
What is the cause of abetalipoproteinemia?
genetic disorder in which b-apoproteins are not produced sufficiently
65
What are the consequences of abetalipoproteinemia?
- - can't form VLDL or CM - - TGs accumulate in intestine and liver - - can't burn dietary fat - - SCFAs can be burned - - fat-soluble things are not available
66
What is the cause of CF?
mucous secretions block the pancreatic duct and prevent excretion of exocrine enzymes
67
What are symptoms of CF?
steatorrhea, ADEK deficiency, eicosanoid deficiency

Drew 922 (12 decks)

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