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unit 6: MCP > Fatty acids and ketones 11 > Flashcards

Fatty acids and ketones 11 Flashcards

1
Q

What does insulin promote in adipocytes: fat uptake or glucose uptake?

A

both !

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2
Q

How is the glycerol backbone generated to synthesize TGs?

A

via glycolysis - G3P

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3
Q

Acyl transferases catalyze the transfer of acyl groups from what substrates to G3P?

A

fatty acyl-coA

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4
Q

Hormone sensitive lipase releases FA preferentially from what?

A

DG and MG (releases FA more slowly from TG)

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5
Q

What activates HSL?

A

catecholamines and glucagon

cAMP dependent protein kinase phosphorylates HSL so that it is more active

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6
Q

What inhibits lipolysis?

A 
NEFAs (via product inhibition)
 and insulin (via phosphatase)
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7
Q

What lipase catalyzes the rate limiting step in lipolysis?

A

adipose triglyceride lipase

- formation of DG from TG

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8
Q

What happens in mice if these enzymes are deficient:

  1. HSL
  2. Adipose triglyceride lipase
A
  1. not obese
  2. obese
    - –indicates its the rate limiting step
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9
Q

What are peripillins?

A

proteins that coat the surface of peripheral lipid droplets

-prevent access of lipases

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10
Q

What disrupts the perilipin sheet, allowing lipase access?

A

phosphorylation by cAMP dependent kinase

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11
Q

What step is the key regulation event in lipolysis?

A

phosphorylation of perilipins

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12
Q

What is lipotransin?

A

protein on the droplet surface that helps HSL dock

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13
Q

How are NEFAs transported in the blood?

A

bound to albumin ALWAYYYYYS

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14
Q

What transporter does glycerol use to leave the cell?

A

AQPad

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15
Q

Describe the delta system

A

Total C: double bond: delta: positions of first C in each double bond

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16
Q

Describe the omega system

A

Total carbons: number of double bond: omega: first C from the methyl side

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17
Q

True or false: all members can be synthesized from the parent member

A

true

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18
Q

True or false: A FA of one class can easily be converted to another by humans

A

FALSEEE

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19
Q

What is the omega formula for Plamitoleic acid?

A

16:1ω-7

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20
Q

What is the omega formula for oleic acid?

A

18:1ω-9

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21
Q

What is the omega formula for linoleic acid?

A

18:2ω-6

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22
Q

What is the omega formula for linolenic acid?

A

18: 3 ω-3

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23
Q

Which fatty acids of this list are essential: oleic, linoleic, linolenic, palmitic?

A

linoleic and linolenic

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24
Q

Can beta oxidation occur with short and medium fatty acids?

A

yes!

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25
Q

What enzyme is involved in activating fatty acids to fatty acyl-coA?

A

thiokinase

26
Q

If the Overall ΔG°’ for activating fatty acids is near 0, what drives the reaction?

A

pyrophosphatase

27
Q

How many ATPs are used to activate a fatty acid for B-oxidation?

A

2

28
Q

What enzyme in the outer mitochondrial membrane, catalyzes the transfer of a LCFA from coA to carnitine?

A

CPT1

29
Q

The carnitine acylcarnitine transporter transports what two molecules which ways? where is this located?

A

inner mito membrane

acylcarnitine into mitochondria
carnitine out of mitochondria

30
Q

Acyl coA is regenerated by what enzyme on the inner mitochondrial membrane?

A

CPTII

31
Q

What three other pathways besides beta oxidation exist to oxidize FA?

A
  1. B ox of LCFAs and polyunsat FA in peroxisomes
  2. alpha-ox of branched chain FAs in mito
  3. omega-ox in ER
32
Q

What is CTP1 inhibited by?

A

malonyl coA

-first product of committed step in FA synthesis

33
Q

What is the first step of beta oxidation?

A

oxidize the alpha-B bond to a double bond
dehyrogenation by acyl-coA dehydrogenase

e- from FADH2 are passed down e- chain

acyl coA –> trans enoyl coA

34
Q

What is the second step of beta oxidation?

A

hydration across the alpha-B double bond

-2,3 enoyl -coA hydrase

trans enoyl coA ->B hydroxyacyl-coA

35
Q

Whats the third step of beta oxidation?

A

dehydrogenation

3- hydroxyacyl coA dehydrogenase

B-hydroxyacyl coA –> B -Ketoacyl coA

36
Q

What is the fourth step in beta oxidation?

A

thiolysis

thiolase

B-ketoacyl CoA –> acyl coA 2 C shortened + acetyl coA

37
Q

What steps involve a trifunctional protein?

A

2, 3, 4

38
Q

How many FADH and NADHs are produced in each round of beta oxidation?

A

one each

39
Q

How many ATP is produced by one FADH?

A

two ATP

40
Q

How many ATP is produced by one NADH?

A

three ATP

41
Q

What is the net gain of ATP in beta oxidation?

A

129 ATP per 16 Carbons –> 8 ATP/C

42
Q

What percent of free energy is converted to heat , what percent to ATP in beta oxidation?

A

60% heat

40% ATP

43
Q

How many ATP/C are produced in glycolysis?

A

36 ATP per 6C –> 6ATP/C

44
Q

If a beta gamma double bond is present, what is the cost?

A

1 FADH2 –> 2 ATP

45
Q

If a delta 4 double bond is present, what is the cost?

A

1 NADPH –> 3 ATP

46
Q

Linoleic acid E will be reduced by how many ATP compared to stearic acid?

A

5 ATP

47
Q

Where and when are ketone bodies produced?

A

liver mitochondria during fasting and starvation

overproduced in type 1 Diabetes

48
Q

Are ketone bodies used as fuel in the liver?

A

NOOO

49
Q

Which ketone bodies can be used as fuel by many tissues including the brain?

A

acetoacetate, B-hydroxybutyrate

50
Q

What ketone body is a metabolic dead end?

A

acetone

51
Q

What do high levels of acetyl coA do?

A

inhibits pyruvate dehydrogenase
activates pyruvate carboxylase

-OAA increases and diverted to glycolysis

52
Q

What is the effect of high levels of NADH in mitochondria from B-oxidation?

A

inhibits isocitrate dehydrogenase
-citrate accumulates

  • OAA is converted to malate
  • malate leaves the mito and used for gluconeogenesis
53
Q

What happens to the excess acetyl coA from B-oxidation?

A

used for making ketone bodies

-does not enter the TCA cycle

54
Q

When are high levels of acetyl coA encountered?

A

during fasting, heavy alcohol, high fat/low carb diets, diabetes

55
Q

In ketone metabolism:
acetyl coA + acetyl coA –> acetoacetyl coA

what enzyme?
what type of reaction?

A

B-ketothiolase

condensation reaction

56
Q

In ketone metabolism:
acetoacetyl coA + acetoacetyl coa –> HMG coA

what enzyme?
what type of reaction?

A

HMG COA synthetase

condensation

57
Q

HMG - COA –> acetyl coA + acetoacetate

what enzyme?

A

HMG-coA lyase

58
Q

What two products are formed from acetoacetate?

A

acetone and b-hydroxybutyrate

59
Q

Why cant extra-hepatic tissues synthesize KBs?

A

lack high levels of HMG-coA synthetase

lack HMG coA lyase

60
Q

What happens in ketoacidosis?

A

more KBs are produced than the extrahepatic tissues can burn and more than kidneys can excrete

lots of glucagon , no insulin

61
Q

Can ketoacidosis happen in type 2 diabetes?

A

nopeeeeee

theres still insulin present

unit 6: MCP (17 decks)

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