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Biochemistry > Exam 3 Zaidi > Flashcards

Exam 3 Zaidi Flashcards

1
Q

source of carbon for FA synthesis

A

dietary carbs

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2
Q

FA synthesis facts

A

mainly in liver, but also adipose tissue, brain, kidney
cytosolic and mitochondric reactions
precursor: acetyl coa

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3
Q

3 phases of FA synthesis

A
  1. cytosolic entry of acetyl coa
  2. generation of malonyl coa
  3. FA chain formation
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4
Q

rate limiting step/enzyme of FA synthesis

A 
acetyl coa --> malonyl coa
acetyl coa carboxylase (ACC) 
inactive as dimer
active as polymer 
cofactors: use ATP and Biotin
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5
Q

FAS complex

A

Fatty acid synthase complex
multienzyme complex
2 homodimers; head to tail conformation
7 enzyme activities and ACP

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6
Q

ACP

A

acyl carrier protein
part of FAS complex
flexible arm

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7
Q

reactions catalyzed by FAS

A

condensation –> reduction –> dehydration –> reduction
^^ all one cycle
6 cycles

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8
Q

FA synthesis steps

A

acetyl ACP –> malonyl ACP –> acetoacetyl ACP –> D3 hydroxbutyryl ACP –> crotonyl ACP –> butyryl ACP

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9
Q

regulation in all 3 phases of FA synthesis

A
  1. ATP citrate lyase
  2. acetyl coA carboxylase
  3. fatty acid synthase
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10
Q

ATP citrate lyase regulation

A

up: phosphorylation, glucose, insulin
down: PUFA, leptin

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11
Q

acetyl coa carboxylase regulation

A

up: citrate, insulin, high carb/low fat
down: long FA, epi, glucagon, AMP

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12
Q

fatty acid synthase regulation

A

up: phosphorylation, insulin, glucocorticoid hormones, high carb/low fat
down: high fat, starvation, high PUFA

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13
Q

elongation of FA

A

palmitate to longer in SER and mitochondria
SER: use malonyl coa
mitochondria: use acetyl coa

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14
Q

desaturation of FA

A

means: increase # of dbl bonds
in SER
by acyl coa desaturases (4 in humans: 4,5,6,9)
FA w dbl bonds beyond C9 and C10 cannot be synthesized in humans!!!!!!!
precursors for it ^^: essential FA

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15
Q

linoleic acid –>

A

arachidonic acid (w6)

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16
Q

linolenic acid –>

A 
eicosapentanoic acid (EPA: w3)
docosahexonoic acid (DHA: w6)
17
Q

energy comparison: carbs and TAGs

A

TAGs give off more energy than carbs

most TAGs are in fat and muscle!!

18
Q

triacylglycerol synthesis

A

dietary: intestinal cells

de novo: hepatocytes and adipocytes

19
Q

triacylglycerol synthesis in liver

A

glucose and glycerol –> glycerol 3 phosphate
Free FA added to G3P –> TAG synthesis
steps:
glycerol 3 phosphate –> lysophosphatidic acid –> phosphatidic acid –> diacyl glycerol –> triacyl glycerol –> VLDL –> blood

upregulated by: excess carbs

20
Q

triacylglycerol synthesis in adipocytes

A

glucose –> G3P
Free FA from chylomicrons/VLDL breakdown
steps: SAME AS IN LIVER

upregulated by: excess carbs AND fat

21
Q

capillary lipoprotein lipase

A

breaks down chylomicrons and VLDL to free FA

22
Q

3 (4) major lipases for FA breakdown

A

Hormone sensitive lipase (HSL)
lipoprotein lipase (LPL)
monoacylglycerol lipase (MAG Lipase)
adipose triglyceride lipase (ATGL) new.

23
Q

what promotes and inhibits TAG mobilization (breakdown)

A

promotes: hunger and exercise
inhibit: fed state

24
Q

HSL regulation

A

glucagon and epinephrine –> phosphorylate/activate HSL –> lipolysis

insulin –> inactivate HSL –> inhibit lipolysis

25
Q

2 phases of FA breakdown

A
  1. activation and transport to mitochondrial matrix

2. beta oxidation

26
Q

T/F: outer and inner mitochondrial membranes are impermeable to FACoA.

A

true.

27
Q

perilipin

A

protein that coats lipids in adipocytes and muscle cells
regulation via PKA
lipolysis regulation: control physical access to HSL

if too much, inhibits lipolysis.

28
Q

fatty acyl coa synthetase

A

phase 1 breakdown enzyme
in outer mit membrane
activates long chain FA with ATP
forms thioester bond –> FACoA

29
Q

carnitine palmitoyltransferase 1 (CPT1)

A

phase 1 breakdown enzyme
aka carnitine acyltransferase
in intermembrane space
form FA- carnitine

RATE LIMITING ENZYME AND REACTION
INHIBITED BY MALONYL COA

30
Q

carnitine-acylcarnitine translocase (CACT)

A

phase 1 breakdown enzyme
antiporter:
FA-carnitine in, carnitine out

FA-carnitine to inner membrane space

31
Q

carnitine palmitoyaltransferase II (CPTII)

A

phase 1 breakdown enzyme
in inner membrane
forms FA-CoA

*now FA-CoA is in mit matrix

32
Q

phase 2 of FA breakdown - beta oxidation steps and what it makes

A

4 steps:

  1. oxidation via acyl coa dehydrogenase (ACAD)
  2. hydration via enol coa hydratase
  3. oxidation via 3-hydroxyacyl coa dehydrogenase
  4. thiolysis via acetyl coa acetyltransferase (B-keto thiolase)

makes: FADH2, NADH, Acetyl CoA

33
Q

ATP from beta ox of palmitic acid

A

makes 7 FADH2, 7 NADH, 8 ACETYL COA, 7 H+

FADH2 = 14 ATP
NADH = 21 ATP
ACETYL COA = 96 ATP
- 2 ATP from palmitate activation

NET: 129 ATP

34
Q

Ketone bodies (3)

A

acetoacetate
b-hydroxybutyrate
acetone

1 forms 2 and 3.

produced in liver ONLY

35
Q

physiological ketoacidosis

A

mild to moderate increase in ketone bodies

36
Q

pathological ketoacidosis

A

glucagon:insulin ratio increases

therefore, FA breakdown

37
Q

increase gluconeogenesis causes

A

decrease OAA

Biochemistry (5 decks)

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