Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biochemistry Exam 3 > Chapter 28: Fatty Acid Synthesis > Flashcards

Chapter 28: Fatty Acid Synthesis Flashcards

1
Q

Most of our need for fats and lipids are met by our…

A

Diet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Fatty acid synthesis occurs in the…

A

Cytosol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

When glucose is abundant, a large amount of _____ is produced that can be used for FA synthesis in cytosol.

A

Acetyl CoA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The first of 3 stages of FA synthesis is:

A

The transfer of acetyl CoA out of the mitochondria into the cytoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

The second of 3 stages of FA synthesis is:

A

The activation of acetyl CoA to form malonyl CoA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The third of 3 stages of FA sythesis is:

A

The repetitive addition and reduction of two carbon units

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Citrate, synthesized in the _____, is transported to the _____ and cleaved by _____ to generate acetyl CoA for FA synthesis.

A

Synthesized in mitochondria and transported to the cytoplasm and cleaved by ATP-citrate lyase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

FA Synthesis requires reducing power in the form of…

A

NADPH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Some NADPH is formed from the oxidation of _____ to _____.

A

Oxaloacetate to Pyruvate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Additional NADPH comes from _____.

A

Pentose Phosphate Pathway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The formation of _____ is the committed step in FA synthesis.

A

Malonyl CoA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Malonyl CoA is synthesized by _____, a biotin-requiring enzyme.

A

Acetyl CoA carboxylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What catalyzes the irreversible rate-limiting step of FA synthesis?

A

Acetyl CoA carboxylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What catalyzes the formation of fatty acids?

A

Fatty acid synthase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

FA synthesis occurs on the _____, a polypeptide link to CoA.

A

Acyl carrier protein (ACP)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What attaches substrates to the ACP?

A

Transacylases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

FA Synthesis consists of a series of reactions. What are they?

A

Condensation, reduction, dehydration and reduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What catalyzes the condensation of acetyl ACP and malonyl ACP to form acetoacetyl ACP?

A

B-ketoacyl synthase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

The next 3 steps convert the keto group at carbon 3 to a methylene group, forming _____.

A

Butyryl ACP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

_____ are consumed as reducing power.

A

2 NADPH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Acetyl ACP to Malonyl ACP (required) convert to what via a condensation reaction?

A

Acetoacetyl ACP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Acetoacetyl ACP converts to _____ via a reduction reaction.

A

D-3-hydroxbutyryl ACP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

D-3-Hydroxbutyryl ACP converts to _____ via a dehydration reaction.

A

Crotonyl ACP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Crotonyl ACP converts to _____ via a reduction reaction.

A

Butyryl ACP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Elongation of FA Chain proceeds by addition of 2 carbons from _____.

A

Malonyl ACP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

The second round of synthesis begins with the condensation of _____ with the newly synthesized _____, forming _____.

A

Condensation of malonyl CoA with butyryl ACP, forming C6-beta-ketoacyl ACP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

The reduction, dehydration, reduction sequence is _____.

A

Repeated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Synthesis continues until _____, which is cleaved by thioesterase to yield _____.

A

C16-acyl ACP to yield palmitate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

The synthesis of palmitate requires?

A
  • 8 Acetyl CoA
  • 14 NADPH
    • 7 ATP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Mammalian FA synthase is composed of one large single polypeptide chain that consists of 2 compartments:

A
  1. Selecting and condensing compartment - condenses the acetyl and malonyl substrates
  2. Modification compartment - carries out the reduction and dehydration activities required for elongation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Tumors require large amounts of _____ to produce precursors for membrane synthesis.

A

Fatty acid synthase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Fatty acid synthase inhibitors…

A

Slow tumor growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Mice treated with fatty acid synthase inhibitors also showed dramatic _____ and may be used to treat _____.

A

Weight loss; obesity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Fatty acid synthase cannot generate fatty acids longer than _____.

A

C16 Palmitate

35
Q

In order to have longer fatty acids, they must be synthesized by _____.

A

Enzymes attached to the endoplasmic reticulum

36
Q

The enzymes that elongate fatty acids extend palmitate by _____, using _____ as a substrate.

A

Adding two carbon units, using malonyl CoA

37
Q

Membrane-bound enzymes generate _____.

A

Unsaturated fatty acids

38
Q

_____ cannot introduce double bonds during FA synthesis.

A

Eukaryotes

39
Q

What introduce double bonds into saturated FAs?

A

Enzymes bound to the endoplasmic reticulum

40
Q

Mammals lack the enzymes that introduce double bonds beyond _____.

A

Carbon 9

41
Q

What are the two essential fatty acids that must be obtained from the diet?

A

Linoleate (C18:2) and Linolenate (C18:3)

42
Q

What is a key regulator of Fatty Acid Metabolism?

A

Acetyl CoA Carboxylase

43
Q

There are 3 mechanisms of regulation of fatty acid metabolism. With Acetyl CoA Carboxylase being the key regulator, what is it inhibited by?

A
  • AMPK
  • Glucagon
  • Epinephrine
  • Palmitoyl CoA
44
Q

There are 3 mechanisms of regulation of fatty acid metabolism. With Acetyl CoA Carboxylase being the key regulator, what is it stimulated by?

A
  • Protein phosphatase 2A (PP2A)
  • Citrate
  • Insulin
45
Q

How does Glucagon and Epinephrine affect Acetyl CoA Carboxylase? Insulin?

A

Glucagon and epinephrine inhibit carboxylase by enhancing AMPK activity.

Insulin activates the carboxylase by causing its dephosphorylation.

46
Q

Excess ethanol consumption can cause _____.

A

Liver damage

47
Q

Ethanol cannot be excreted, it must be…

A

Metabolized in the liver

48
Q

One pathway for ethanol processing consists of two steps and leads to _____.

A

Excess production of NADH

49
Q

Excess NADH inhibits _____. This results in _____.

A
  • Inhibits gluconeogenesis
  • Results in: Hypoglycemia
50
Q

Excess NADH inhibits _____ and stimulates _____, leading to accumulation of fats in liver, known as _____.

A
  • Inhibits fatty acid degradation
  • Stimulates fatty acid synthesis
  • Results in: fatty liver
51
Q

Fatty Acid Synthesis committed step:

A

Acetyl CoA carboxylase

52
Q

Fatty Acid Degradation committed step:

A

Carnitine acyltransferase I

53
Q

FA Degradation inhibited by _____.

A

Malonyl CoA

54
Q

Liver converts some of the acetate to acetyl CoA, which cannot be processed by _____ due to inhibition by _____.

A

Citric acid cycle due to inhibition of NADH

55
Q

The build-up of acetyl CoA can lead to _____ by the liver, which exacerbates the _____.

A

Ketone body secretion which exacerbates the lactic acidosis

56
Q

If acetate cannot be processed, _____ accumulates.

A

Acetaldehyde

57
Q

Acetaldehyde is very reactive and modifies reactive groups of proteins, causing _____.

A

A loss of protein function

58
Q

As protein damage accumulates,

A

Liver function can fail

59
Q

3 Stages of liver damage by excess ethanol consumption:

A
  1. Fatty liver (Liver can be 2X the normal size)
  2. Alcoholic hepatitis
  3. Cirrhosis (More shrunken liver)
60
Q

Chronic ethanol ingestion alters carbohydrate metabolism and leads to a fatty liver due primarily to an increase in which of the following?

  • NADH
  • NADPH
  • ATP
  • ADP
  • None of the above
A

NADH

61
Q

Phospholipid synthesis does NOT require:

A

Sphinogsine

62
Q

Tay-Sachs disease is caused by an inability to degrade:

A

Gangliosides

63
Q

Fatty acid synthesis occurs in…

A

Occurs in the cytosol in all species

64
Q

. The rate limiting step for fatty acid synthesis is promoted by:

A

Acetyl CoA carboxylase

65
Q

During the chain elongation step of fatty acid synthesis, the newly added carbons come directly from:

A

Malonyl ACP

66
Q

T or F: Acetyl CoA carboxylase is found exclusively in the mitochondria.

A

False

67
Q

High concentrations of acetyl CoA in the mitochondria:

A

Lead to increased transport of citrate from the mitochondria to the cytosol

68
Q

T or F: High levels of insulin stimulate acetyl CoA carboxylase.

A

True

69
Q

T or F: Acetyl CoA carboxylase produces malonyl CoA.

A

True

70
Q

T or F: Acetyl CoA carboxylase catalyzes the rate-limiting step for fatty acid synthesis.

A

True

71
Q

T or F: Acetyl CoA carboxylase is regulated by phosphorylation and allosteric modification.

A

True

72
Q

Fatty acids are elongated and desaturated by…

A

Enzymes attached to the ER

73
Q

Excess NADH enhances _____. This results in _____.

A
  • Enhances lactate production
  • Results in: Lactic Acidosis
74
Q

Fatty acid oxidation is increased by:

  • Low insulin levels
  • Low carbohydrate levels
  • High epinephrine levels
  • High glucagon levels
A

All are correct

75
Q

Fatty acid oxidation…

A

Requires activation of fatty acids to the CoA form

76
Q

What is the purpose of the carnitine shuttle system?

A

To transport fatty acids from the cytosol to the mitochondrial matrix

77
Q

T or F about fatty acids in mammals:

Double bonds are added during the synthesis of fatty acids

A

False

78
Q

T or F: About fatty acids in mammals:

Fatty acids in triacylglycerols provide only limited energy storage

A

False

79
Q

T or F: about fatty acids in mammals:

Elongases must be used to synthesize fatty acids longer than 18 carbons

A

True

80
Q

T or F: about fatty acids in mammals:

Mammals can synthesize all the fatty acids they need

A

False

81
Q

T or F about fatty acids in mammals:

Fatty acids are rarely made in mammals

A

False

82
Q

Which statement comparing fatty acid synthesis to fatty acid degradation is TRUE about both processes?

  • They both occur in the cytosol
  • They both utilize intermediates covalently attached to ACP
  • They both can be regulated by insulin levels
  • They both require reduction steps
  • They both generate energy
A

They both can be regulated by insulin levels

83
Q

The building block for triacylglycerol synthesis is:

A

Glycerol 3-phosphate

Biochemistry Exam 3 (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions