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KCU Biochem Exam 3 > Exam 3 Review Zaidi > Flashcards

Exam 3 Review Zaidi Flashcards

1
Q

Where does fatty acid synthesis take place?

A

Primarily in the liver, but also occurs in adipose tissue, brain, kidneys and lactating mammary glands

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2
Q

What does fatty acid synthesis require?

A

Coordination between cytosolic and mitochondrial reactions

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3
Q

What is the end product of fatty acid synthesis?

A

Palmitic acid

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4
Q

What is the precursor of fatty acid synthesis?

A

Acetyl CoA

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5
Q

What is the first phase of fatty acid synthesis?

A

Cytosolic entry of acetyl CoA

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6
Q

What is the second phase of fatty acid synthesis?

A

Generation of Malonyl CoA (rate limiting reaction)

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7
Q

What is the third phase of fatty acid synthesis?

A

Fatty acid chain formation (enzyme fatty acid synthase catalyzes 7 reactions that incorporate acetyl CoA, Malonyl CoA into palmitate (a C16 fatty acid))

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8
Q

What is the shuttle system that moves reactants into the cytosol?

A

Citrate Shuttle which moves citrate to the cytosol where it is formed to oxalocetate by ATP citrate lyase where acetyl CoA is a byproduct

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9
Q

What is used as a co-factor in the conversion of acetyl CoA to Malonyl CoA?

A

Biotin

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10
Q

What is the function of Malonyl CoA?

A

Regulator that inhibits carnitine acyltransferase

Prevents fatty acid synthesis and degradation from occurring simultaneously

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11
Q

Where does fatty acid synthesis take place?

A

Fatty Acid Synthase complex

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12
Q

What is fatty acid synthase composed of?

A

2 identical dimers, 7 enzyme activities and an acyl carrier protein

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13
Q

What is the formula for fatty acid synthesis?

A

1 Acetyl CoA+7 Malonyl CoA+14 NADPH+14 H+

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14
Q

What is the order of cycles of fatty acid synthase?

A

Condensation, reduction, dehydration, reduction performed 7 times before product release

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15
Q

What are the points of regulation for fatty acid synthesis?

A

ATP citrate lyase Phase 1
Acetyl CoA carboxylase Phase 2 (rate limiting step)
Fatty acid synthase Phase 3

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16
Q

How is ATP citrate lyase regulated?

A

Stimulated by phosphorylation
Expression induced by glucose/insulin
Induction of gene expression counteracted by PUFAs and leptin

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17
Q

How is acetyl CoA carboxylase regulated?

A

Allosterics
Phosphorylation and dephosphorylation
Induction

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18
Q

How is FAS regulated?

A

Allosterics- presence of phosphorylated sugars increase activity
Induction and repression at genetic level

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19
Q

How is fatty acids elongated?

A 
Occurs in mitochondria or SER
Lengthened 2 carbons at a time
NADPH used as reducing power
SER uses malonyl CoA as carbon donor
Mito uses acetyl CoA as carbon donor
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20
Q

What is desaturation?

A

Introduction of double bonds in fatty acids

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21
Q

Where does desaturation occur?

A

SER using NADPH or NADH and oxygen catalyzed by acyl CoA desaturases

22
Q

How many desaturases do humans have and where do they induce double bonds

A

4

Between carbons 4-5, 5-6, 6-7, 9-10

23
Q

Can fatty acids with double bonds beyond C9 and 10 be synthesized in humans?

A

No, must be consumed in diet, known as essential fatty acids ie Omega 3 and Omega 6

24
Q

What is the precursor that must be ingested to form arachidonic acid?

A

Linoleic acid, used to make eicosanoids

25
Q

What is the precursor that must be ingested to form eicosapentanoic acid?

A

Linolenic acid, used to make eicosapentanoic acid and docosahexanoic acid

26
Q

What class of horomone is arachidonate and what is it used for?

A

Eicosanoid hormone, used as a precursor to several classes of signal molecules

27
Q

What is the general make up of a prostaglandin?

A

20 carbon fatty acid containing a 5-carbon ring

28
Q

How many classes are there of prostaglandin?

A

9, designated PGA-PGI

29
Q

Eicosanoids are considered long or short lived?

A

Short and are called local hormones because they are short lived

30
Q

What does prostaglandins stimulate?

A

Inflammation, regulate blood flow to particular organs, control ion transport across membranes, modulate synaptic transmission, induce sleep

31
Q

How does aspirin work?

A

Blocking the enzyme that converts arachidonate into PGH, which accounts for its wide range effects on inflammation, fever, pain, blood clotting

32
Q

What is a TAG?

A

Triacylglycerol, major storage form of fatty acid

33
Q

What are the sources of TAGs?

A

Dietary: processed in intestinal cells, De Novo in hepatocytes and adipocytes

34
Q

What is perilipin?

A

Family of proteins that coat lipid droplets in adipocytes and muscle cells, regulate liolysis by controlling physical access to lipid breakdown enzymes

35
Q

What does the overexpression of perilipin 1 inhibit?

A

Lipolysis and its knock-out has converse effect

36
Q

What is a major target of obesity treatments?

A

Perilipin

37
Q

What is the first phase of fatty acid break down?

A

Fatty acid activation, occurs in cytosol

38
Q

What is the second phase of fatty acid break down?

A

Beta oxidation, primarily occurs in mito-matrix

39
Q

What is the rate limiting step of fatty acid break down?

A

Carnitine acyltransferase 1, inhibited by malonyl CoA

40
Q

What is the four steps of beta-oxidation?

A

Oxidation, hydration, oxidation, thiolysis

41
Q

What is the first enzyme of fatty acid breakdown?

A

Acyl CoA dehydrogenase

42
Q

What is the second enzyme of fatty acid breakdown?

A

Enoyl CoA hydratase

43
Q

What is the third enzyme of fatty acid breakdown?

A

Beta hydroxyl acyl CoA dehydrogenase

44
Q

What is the fourth enzyme of fatty acid breakdown?

A

Acyl CoA transferase or ketothiolase

45
Q

How much ATP is released from beta-oxidation of palmitic acid?

A

131- 2 used during activation of palmitate= 129

46
Q

What is the saying describing the link between lipid and carbohydrate oxidation?

A

Fats burn in the flame of carbohydrates

47
Q

What happens to excess unused Acetyl CoA?

A

Condenses to form ketone bodies

48
Q

What describes ketone bodies?

A

Water-soluable and acidic compounds

49
Q

Where are ketone bodies produced?

A

Liver only

50
Q

What do ketone bodies provide?

A

Provides energy for peripheral tissues and brain during starvation

KCU Biochem Exam 3 (3 decks)

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