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BMS test 2 > Biochem: Lipids > Flashcards

Biochem: Lipids Flashcards

1
Q

Lipids can be broken down structurally into 2 main classes:

A
  1. those based on fatty acid structure
  2. those based on isoprenoid structure
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2
Q

is unsaturated fatty acid, the ones with double bonds or no double bonds

A

has the double bonds

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3
Q

Does cis or trans form create a “bend” in the structure which increases the membrane fluidity?

A

cis

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4
Q

does cis bonds allow for looser and tighter packing of phospholipids?

A

looser, more fluidity

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5
Q

where does fatty acid synthesis occur?

A

cytoplasm

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6
Q

what are the substrates of fatty acid synthesis?

A

acetyl CoA and Malonyl CoA

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7
Q

what is malonyl CoA?

A

Acetyl CoA with an extra CO2 group added

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8
Q

what enzyme do you need for fatty acid synthesis?

A

fatty acid synthase

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9
Q

how many fatty acid chains can be made at once with one fatty acid synthase?

A

2 fatty acid chains can be made

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10
Q

the fatty acid synthase contains 2 S groups which are from?

A

one from cysteine and one from B5

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11
Q

Cysteine binds with what?

A

acetyl groups

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12
Q

B5 binds with what?

A

malonyl groups

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13
Q

what are some Coenzymes for fatty acid synthesis?

A

B7, B5, and B3

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14
Q

what does B7 (biotin) do?

A

helps add CO2 to acetyl CoA to make malonyl CoA

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15
Q

what is the enzyme that converts acetyl CoA to Malonyl CoA?

A

Acetyl CoA Carboxylase

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16
Q

Explain the steps of the fatty acid synthesis

A
  1. acetyl group joins
  2. malonyl group joins
  3. acetyl and malonyl groups combines with loss of CO2
  4. oxygen removed as water, NADPH donates H’s
  5. fatty acid chain shifts over
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17
Q

how do you get to a 16 carbon chain?

A

you keep adding malonyl CoA until you get to 16 carbon

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18
Q

when you get the desired number of carbons, how do you get the chain off the enzyme?

A

use water to break the bond by hydrolysis

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19
Q

how do you make odd-numbered fatty acid chains?

A

starting with propionyl CoA (3C) rather than acetyl CoA (2C) in step one can make odd numbered chains

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20
Q

what is the enzyme to create double bonds hence creating unsaturated fatty acids?

A

desaturase enzymes

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21
Q

what are the 3 hormones that regulate fatty acid synthesis?

A

glucagon, insulin, epinephrine

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22
Q

how does glucagon and epinephrine regulate fatty acid synthesis?

A

both inhibit acetyl CoA carboxylase

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23
Q

how does insulin regulate fatty acid synthesis?

A

activates acetyl CoA carboxylase

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24
Q

what are triglycerides

A

3 fatty acids attached to a glycerol backbone via an ester link

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25
Q

which packs tighter and therefore stores energy more efficiently? triglycerides or glycogen?

A

triglycerides

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26
Q

what is the process called for triglyceride synthesis?

A

lipogenesis

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27
Q

where does lipogenesis happen?

A

liver and adipocytes: in the cytosol

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28
Q

what are the steps of lipogenesis?

A
  • make the substrates
  • transfer 2 fatty acid chains to the backbone sequentially
  • replace the phosphate on the backbone with the 3rd fatty acid chain
29
Q

what enzyme adds a phosphate to glycerol to create glycerol-3-phosphate? (glycerol backbone)

A

glycerol kinase

30
Q

what is a way adipose tissue and the liver make the glycerol backbone?

A

Convert DHAP to glycerol-3-phosphate using glycerol-3-phosphate dehydrogenase

31
Q

after making the back bone, what do you make?

A

make the fatty acyl CoA

32
Q

fatty acids are added to a CoA carrier using what?

A

ATP

33
Q

what does the CoA do to the fatty acid?

A

carry the fatty acid chains to the backbone and transfer them over

34
Q

how many fatty acid chains do you add to the glycerol-3-phosphate

A

2 fatty acid chains

35
Q

what is the last step to triglyceride synthesis?

A

removing the P and adding the last fatty acid chain

36
Q

what do both phospholipids and glycosphingolipids both contain:

A
  1. a backbone
  2. lipid
  3. head group
37
Q

how are phosphoglyceride formed?

A

you start with a phospholipid and then an ethanol amine is added to it

38
Q

how to add a head group to a phosphoglyceride?

A

first, a CMP is added to create a good leaving group. Next, the CMP is removed and head group is attached via nucleophilic substitution

39
Q

what is sphingomyelin?

A

phospholipid that is a sphingolipid

40
Q

what is different between sphingolipids and phospholipids?

A

the backbone, for sphingolipids, the backbone is sphingosine

41
Q

what type of lipids are cerebrosides and gangliosides?

A

sphingolipids

42
Q

what are the headgroups of gangliosides?

A

1 or more sialic acid plus 1 or more additional monosaccharides

43
Q

what are the headgroups of cerebrosides?

A

monosaccharide head group

44
Q

accumulation of sphingolipids leads to what?

A

sphingolipid storage diseases

45
Q

what’s Tay-Sachs Disease?

A

GM2 accumulates in lysosomes due to an enzyme deficiency
- most severe excesses occur in the brain, build up leads to neuronal cell damage

46
Q

what are eicosanoids?

A

derived from arachidonic acid or similar 20 carbon fatty acids

47
Q

prostaglandins is a ?

A

eicosanoid

48
Q

what are some physiological functions of eicosanoids?

A
  • vasodilation
  • vasoconstriction
  • platelet aggregation
49
Q

what are waxes?

A

mixtures of non-polar molecules, including fatty acids linked to long-chain hydrocarbon alcohols via ester bonds

50
Q

what are the categories of isoprenoids?

A
  1. terpenes
  2. mixed terpenes
  3. steroids
51
Q

what are terpenes?

A

isoprene units linked together

52
Q

what is the smallest terpene?

A

2 isoprene units linked together = monoterpene

53
Q

diterpene

A

4 isoprene

54
Q

squalene

A

a triterpene

55
Q

beta carotene

A

tetraterpene

56
Q

what is a mixed terpene

A

terpenes with a non-terpene component attached

57
Q

what is steroids

A

complex molecules made from 6 isoprene units and contain 4 fused rings with various substituents
- made from cholesterol

58
Q

what are the steps to cholesterol synthesis??

A

3 acetyl CoA -> HMG-CoA -> HMG-CoA reductase creates mevalonate -> sqalene -> cholesterol

59
Q

what is the rate limiting enzyme for cholesterol synthesis?

A

HMG-CoA reductase

60
Q

what does high cholesterol do to HMC-CoA reductase?

A

it inhibits it from creating more cholesterol

61
Q

what is a cholesterol-lowering drug?

A

atorvastatin (lipitor)

62
Q

what does the liver use cholesterol for?

A
  • make bile
  • make lipoproteins (LDL) to carry cholesterol to the tissues
63
Q

how does LDL turn to cholesterol at the tissue cells

A

LDL binds to receptor on the cell and is internalized
LDL is broken down inside the cell and cholesterol is released

64
Q

what is familial hypercholesteremia?

A

an inherited defect in LDL-receptors which leads to an increase in circulating LDL, and therefore cholesterol in the blood which increases the risk of myocardial infarction

65
Q

cholesterol is a precursor to what?

A

steroid hormones

66
Q

how does cholesterol convert to steroid hormones?

A

cholesterol is first converted to pregnenolone, which is then converted to other steroid hormones

67
Q

plant sterols can compete with intestinal cholesterol absorption which in turn do what?

A

helps lower LDL cholesterol levels

68
Q

cardiac glycosides are derivatives of what?

A

plant sterols

BMS test 2 (11 decks)

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