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Biochemistry > Lecture 33 - Lipid Metabolism II > Flashcards

Lecture 33 - Lipid Metabolism II Flashcards

1
Q

Fatty acid synthesis occurs in the (liver/all cells)

A

liver

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2
Q

Fatty acid break down occurs in (liver/all) cells

A

all

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3
Q

Enzymes for FA synthesis are localized in the (cytoplasm/mitochondria)

A

cytoplasm

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4
Q

Enzymes for FA degradation are localized in the (cytoplasm/mitochondria)

A

mitochondria

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5
Q

Acetyl-CoA is converted to _________ as the first step of FA synthesis.

A. malonyl-CoA
B. Acetoaceyl-CoA
C. Malonate
D. 3-D-hydroxybutyrate

A

A. malonyl-CoA

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6
Q

Synthesis of acetyl CoA for FAs occurs when ____ is produced in the mitochondria.

A

citrate

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7
Q

Citrate is formed in the mitochondria utilizing what two enzymes?

A

Pyruvate carboxylase (to form oxaloacetate)

PDH (to form acetyl-CoA)

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8
Q

Following citrate formation, it is shuttled to the mitochondria to be broken down into OAA and Acetyl-CoA. What enzyme is used for this breakdown?

A. malic enzyme
B. PDH
C. citrate lyase
D. pyruvate carboxylase

A

C. citrate lyase

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9
Q

For continued generation of Acetyl-Coa, malate is transformed back into pyruvate via ______, which also produces NADPH

A

malic enzyme

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10
Q

Addition of CO2 to acetyl-CoA produces ______ via acetyl-CoA carboxylase.

A

malonyl-CoA

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11
Q

Rate limiting step in FA synthesis

A

Acetyl-CoA to malonyl-CoA

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12
Q

(+) allosteric regulator of ACC

A. Insulin
B. glucagon
C. High carb diet
D. Citrate

A

D. citrate (precursor to the citrate-> OAA/Acetyl-CoA reaction)

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13
Q

(-) allosteric regulator of ACC

A. Citrate
B. Long chain FAs
C. Epinephrine
D. High carbohydrate diet

A

B. Long chain FAs

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14
Q

Control of ACC by dephosphorylation

A

insulin (high insulin indicates a large carbon pool, forcing dephosphorylation of ACC, producing more FAs)

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15
Q

Phosphorylation of ACC is caused by what compounds?

A

epinephrine and glucagon (indicate low energy state, no need to take “time” to produce FAs)

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16
Q

In the presence of low blood glucose, epinephrine and glucagon are released. These molecules inhibit acetyl-coa carboxylase, and prevent the formation of fatty acids. The Acetyl-CoA is instead utilized to make what compounds for energy?

A

Ketone bodies

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17
Q

Malonyl-CoA undergoes addition of two carbon fragments by the enzyme _____ until _____ is formed.

A

Fatty Acid Synthase Complex;

palmitate (16:0)

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18
Q

The fatty acid synthase complex contains what residue that is important for addition of CO2 to malonyl-CoA?

A

phosphopantetheine residue (PP)

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19
Q

PP of the acyl carrier protein on one FAS domain is attached to the _____ of the other FAS domain.

A

cysteinyl sulfhydryl group

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20
Q

The first step of FA synthesis is the _____ step.

A. condensation
B. reduction
C. Dehydration

A

A. condensation (adding of acetyl-CoA to malonyl-CoA to form acetoacetyl-CoA)

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21
Q

The second step of FA synthesis is the ___ step.

A. condensation
B. reduction
C. Dehydration

A

B. reduction (formation of ketoalcohol with production of NADP+)

22
Q

The third step of FA synthesis is the ____ step.

A. condensation
B. reduction
C. Dehydration

A

C. dehydration (loss of water to form double bond)

23
Q

The final step in FA synthesis is the ___ step.

A. condensation
B. reduction
C. Dehydration

A

B. Reduction (FA lengthened by two carbons)

24
Q

FAS is stimulated by what allosteric effect?

A

Presence of phosphorylated sugars (indicates large amounts of carbohydrates)

25
Q

Like ACC, FAS is also stimulated at the genetic level by ______.

A

high carbohydrate, low fat diets

26
Q

Desaturation of FAs occurs with what three enzymes?

A

NADH-Cytochrome B5 reductase

Cytochrome B5

Stearoyl CoA desturase

27
Q

De Novo synthesis of Triacylglycerols occurs in what two cells types?

A

Hepatocytes

Adipocytes

28
Q

Hepatocytes utilize _____ to form G-3-P

A. glycerol
B. glucose
C. glycogen
D. DHAP

A

A. glycerol

29
Q

Adipocytes utilize ___ to help form G-3-P in conjuction with hepatocytes.

A. glycerol
B. glucose
C. glycogen
D. DHAP

A

B. Glucose

30
Q

Following formation ofo G-3-P, ___ is cleaved to form phosphatidic acid.

A

2x Acyl-CoA

31
Q

G-3-P + Acyl-CoA forms ____

A

Phosphatidic acid

32
Q

Following the removal of the inorganic phosphate from phosphatidic acid, a ___ is produced.

A. ketone
B. diacylglycerol
C. monoacylglycerol
D. triacylglyercol

A

B. diacylglycerol

33
Q

The addition of acyl group to the DAG molecule in TAG synthesis produces _______.

A

TAG (triacylglycerol)

34
Q

TAGs are packaged into _____ in the liver.

A

VLDL

35
Q

Oxidation of arachidonic acid produces _______.

A

eicoisanoids

36
Q

What are the 4 families of eicosanoids?

A

1) prostaglandins
2) prostaclycins
3) thromboxanes
4) leukotrienes

37
Q

What two phospholipids are produced by reaction of a CTP-Head group with DAGs?

A

Phosphatidylcholine

Phosphatidylethanolalmine

38
Q

What two phospholipids are produced from CDP-DAGs?

A

Phosphatidylinositol

Cardiollipin

39
Q

Ethanolamine can be produced by ______ of phosphatidylserine.

A

decarboxylation

40
Q

phosphatidyleserine can be formed adding _____ to ehtanolamine.

A

serine

41
Q

Phosphatidyletanolamine can be methylated to form _____

A

phosphatidylcholine

42
Q

Biosynthesis of cholesterol is regulated primarily by ______.

A. content of cholesterol in the PM
B. dietary intake
C. lysis of cell PMs

A

B. dietary intake

43
Q

Approximately __ of cholesterol is produced by the liver daily.

A

1 gram

44
Q

Acetyl-CoA is converted to mevalonate by ______.

A

HMG CoA Reductase (rate limiting step of cholesterol biosynthesis)

45
Q

Production of the cholesterol ring begins at what intermediate?

A. mevalonate
B. dimethylallyl pyrophosphate
C. lanosterol
D. squalene

A

D. squalene

46
Q

HMG CoA reductase forms HMGCoA by combining ____ and _____.

A

acetoacetyl-CoA

acetyl-CoA

*Similar as the formation of FAs, but utilizing a different enzyme

47
Q

The major carbon source for fatty acid synthesis is ____.

A. TAGs
B. Cholesterol
C. Amino Acids
D. Dietary carbohydrates

A

D. Dietary carbohydrates

48
Q

Which of the following contains the highest TAG content?

a. TAG
b. VLDL
c. LDL
D. HDL

A

a. TAG

49
Q

Which of the following contains the largest amount of cholesterol?

a. TAG
b. VLDL
c. LDL
D. HDL

A

C. LDL

50
Q

Which of the following contains the largest amount of protein/phospholipids?

a. TAG
b. VLDL
c. LDL
d. HDL

A

D. HDL

Biochemistry (43 decks)

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