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DMD 5242 > Amino Acids and urea cycle (Watt's questions too) (complete) > Flashcards

Amino Acids and urea cycle (Watt's questions too) (complete) Flashcards

1
Q
  1. An 16 C fatty acid is called hexadecenoic acid. If there is one cis bond between the 9th and 10th carbons the name of the fatty acid would be
A

a. (*) 16:1(Δ9) cis-9-hexadecenoic acid
b. 16:2(Δ9,10) cis-9-hexadecenoic acid
c. ω9 Δ9) cis-ohexadecenoic acid
d. ω9,10 cis-hexadecenoic acid

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2
Q
  1. The melting temperature of Fatty acids
A

a. (*) Increases with chain length
b. Decreases with chain length
c. Is not influenced by chain length
d. None of the above

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3
Q
  1. Unsaturated fatty acids are
A

a. (*) less ordered than saturated fatty acids
b. More ordered than saturated fatty acids
c. Do not form micelles
d. Always found with trans bonds

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4
Q
  1. Glycerol phospholipids are composed of:
A

a. A glycerol backbone
b. 2 fatty acid chains
c. a polar head group
d. (*) all of the above

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5
Q
  1. Plasmologen differs from normal glycerol phospholipids because the fatty acid is linked to the glycerol backbone by:
A

a. Amide linkages
b. Thiol linkages
c. (*) Ether linkages
d. Ceramide linkages

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6
Q
  1. The lipid sphingomyelin is important in:
A

a. Beta oxidation
b. Lipid synthesis
c. (*)Neuron stabilization
d. Pentose phosphate pathway

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7
Q
  1. Lipid digestion is aided by bile salts from the
A

a. Pancreas
b. Liver
c. (*) Gall bladder
d. Splene

They are stored in the gall bladder before they are sent to the small intestine

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8
Q
  1. Lipid breakdown in cells that causes perilipin phosphorylation and activation of lipases that break down glycerol fatty acids is activated by:
A

a. (*) Glucagon
b. Insulin
c. Cholesterol
d. Glucose

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9
Q
  1. Beta oxidation of fatty acids follows the following steps:
A

a. 1) Oxidation by an NAD dehydrogenase, 2) hydration of a double bond, 3) oxidation by a FAD dehydrogenase, 4) cleavage of acetyl CoA by thiolase.
b. (*) 1) Oxidation by an FAD dehydrogenase, 2) hydration of a double bond, 3) oxidation by a NAD dehydrogenase, 4) cleavage of acetyl CoA by thiolase.
c. 1) Oxidation by an NAD dehydrogenase, 2) oxidation by a FAD dehydrogenase 3) hydration of a double bond, 4) cleavage of acetyl CoA by thiolase.
d. None of the above.

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10
Q
  1. Double bonds in fatty acids:
A

a. Completely inhibit fatty acid beta oxidation
b. (*) Require additional enzymes to create correct stereochemistry for complete beta oxidation
c. Have no effect on Beta oxidation
d. Cause oxidative stress

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11
Q
  1. Odd numbers of carbons in fatty acids
A

a. Are not substrates for any beta oxidation reactions
b. Are processed normally leaving a single carbon unit in the last step
c. (*) Are eventually converted to succinyl CoA for entry into the TCA cycle.
d. Never occur in nature

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12
Q
  1. Vitamin B12 is a prosthetic group in enzymes that
A

a. Allows rapid electron transfer reactions like heme
b. (*) stabilizes radical reactions
c. binds magnesium ions
d. cleaves double bond in fatty acids during beta oxidation

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13
Q
  1. The formation of Ketone bodies
A

a. Are toxic
b. Free up NAD for further redox reactions
c. (*) Free up Coenzyme A for further reactions
d. Stimulates glucose uptake

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14
Q
  1. The biotin cofactor:
A

a. Is linked to lysine in the active site of enzymes
b. Is a 1 C transfer prosthetic group
c. Gets its C from HCO3- in solution
d. (*) All of the above

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15
Q
  1. Fatty acid synthase catalyzes the elongation of 2 C units by
A

a. Condensation of the growing chain with activated acetate
b. Reduction of carbonyl to hydroxyl
c. Dehydration of alcohol to trans-alkene
d. Reduction of alkene to alkane
e. (*) All of the above

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16
Q
  1. NADPH and NADH have separate overall purposes
A

a. NADP(H) functions in anabolic reactions
b. NADH functions in catabolic reactions
c. NADPH and NADH are interchangeable
d. (*) answers A and B are true

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17
Q
  1. AMP is attached to a substrate in which cycle:
A

a. TCA cycle
b. (*) Urea Cycle
c. Lipid Beta oxidation
d. Glycolysis

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18
Q
  1. Ketone bodies come from one class of amino acids C skeletons. The carbon skeletons of other amino acids are used for:
A

a. Fatty acid synthesis
b. Protein synthesis
c. (*) Gluconeogenesis
d. Glycolysis

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19
Q
  1. Proteins are fragmented into their individual amino acids by:
A

a. Bacteria in the small intestine
b. The change of pH from the stomach to the small intestine
c. (*) Protease enzymes
d. Bile salts

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20
Q
  1. Protease enzymes play an important role in
A

a. Glycolysis
b. Glycogen hydrolysis
c. The citric acid cycle
d. (*) Digestion of proteins

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21
Q
  1. Amino Acids are absorbed by:
A

a. One specific transporter that recognizes all amino acids
b. (*) Transporters that transport amino acids based on their charges such as neutral amino acids, positively charged amino acids or negatively charged amino acids.
c. Absorbing the protein and hydrolyzing the protein inside the individual cells
d. Each amino acid has its own transport enzyme.

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22
Q
  1. Amino transferase enzymes in the serum function to:
A

a. Release ammonia in the serum
b. Add amino groups to glucose for absorption into cells
c. Signal for protein degradation as the priority fuel
d. (*) Indicate damage to organs such as liver or heart.

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23
Q
  1. Tissue damage is indicated by the presence of
A

a. (*) Amino transferase enzymes in serum
b. Insulin resistance in serum
c. Glycogen production in serum
d. Gluconeogenesis enzymes in the mitochondria

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24
Q
  1. Alanine plays an important role in Nitrogen metabolism related to exercise because it:
A

a. Transfers oxaloacetate to the liver
b. Transfers alpha keto glutarate to the spleen
c. (*) Comes from pyruvate in the muscle and delivers pyruvate to the liver
d. Is absorbed by the liver without an amino acid transporter.

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25
Q
  1. Arginine is involved in which cycle:
A

a. Glycolysis
b. Gluconeogenesis
c. The Urea cycle
d. The TCA cycle

C

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26
Q
  1. AMP is attached to a substrate in which cycle:
A

a. TCA cycle
b. Urea Cycle
c. Lipid Beta oxidation
d. Glycolysis

B

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27
Q
  1. Ketogenic amino acids are used for:
A

a. Ketolysis
b. Glycolysis
c. Forming glycogen
d. Making ketone bodies

D

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28
Q
  1. Ketone bodies come from one class of amino acids C skeletons. The carbon skeletons of other amino acids are used for:
A

a. Fatty acid synthesis
b. Protein synthesis
c. Gluconeogenesis
d. Glycolysis

C

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29
Q
  1. Protease enzymes play an important role in
A

a. Glycolysis
b. Glycogen hydrolysis
c. The citric acid cycle
d. Digestion of proteins

D

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30
Q
  1. Amino transferase enzymes in the serum function to:
    a. Release ammonia in the serum
    b. Add amino groups to glucose for absorption into cells
    c. Signal for protein degradation as the priority fuel
    d. Indicate damage to organs such as liver or heart.
A

D

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31
Q
  1. Arginine is involved in which cycle:
    a. Glycolysis
    b. Gluconeogenesis
    c. The Urea cycle
    d. The TCA cycle
A

C

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32
Q

NADPH vs. NADH one is anabolic, one is catabolic whichi is which

A

NADPH is anabolic

NADH is catabolic

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33
Q

What is the molecule that many things catabolise into, many things are anabolized from, and is used in the citric cycle

A

Acetyl-CoA

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34
Q

What are the reasons that our body will break down amino acids

A
  1. We have leftover amino acids
  2. Excess dietary amino acids
  3. When carbs are in short supply (for energy)
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35
Q

What are things that can cause us to have a short supply of carbs, and thus break down amino acids

A

Starvation

diabetes mellitus

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36
Q

Are peptide bonds relatively strong and stable, or weak and unstable

A

stable

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37
Q

are peptide bonds sensitive to acid

A

yes

38
Q

What is pepsin

A

a protease found in the stomach

39
Q

What is pepsinogen

A

the precursor to pepsin

40
Q

what turns our pepsinogen into pepsin

A

the acid in the stomach

41
Q

what does pepsin do

A

break down protein

42
Q

What are zymogens

A

inactive precursors to proteases

43
Q

why is it important to store proteases in an inactive form as zymogens

A

because if we had active proteases we would start degrading the proteins in our cells

44
Q

What causes acute pancreatis

A

the zymogens in the pancreas become active proteases and start degrading the protein of the pancreas

45
Q

What activates zymogens in the small intestine

A

other enzymes in the small intestine

46
Q

What is the first protease to degrade proteins

A

pepsin (cleaves proteins into peptides)

47
Q

What are the four proteases found in the small intestine

A
  1. trypsin
  2. chymotrypsin
  3. aminopeptidase
  4. Carboxypeptidases (A and B)
48
Q

What does trypsin do in the small intestine

A

takes proteins and large peptides and cleaves them into smaller peptides

49
Q

what does chmotrypsin do in the small intestine

A

takes proteins and large peptides and cleaves them into smaller peptides

50
Q

what does aminopeptidase do in the small intestine

A

takes small peptides and breaks them down into amino acids

51
Q

what do carboxypeptidases ( A and B) in the small intestine

A

takes small peptides and breaks them down into amino acids

52
Q

What is the process in which aminopeptidases and carboxypeptidases break down peptides into amino acids

A

they start at the ends of the peptides and take off one amino acid at a time

53
Q

what is the process by which trypsin and chymotrypsin take proteins and large peptides and break them down to smaller peptides

A

they just chain the peptide chain at certain points in the middle of the peptide

54
Q

What kinds of transport do amino acids use to enter the intestinal epithelial cells and then into the blood stream

A

both active and passive (facilitated) transport

55
Q

is there one amino acid transporter than allows amino acids to enter the intestinal epithelial cells

A

nope

56
Q

What are the different kinds of amino acid transporters

A
  • neutral amino acid transporters
  • basic amino acid transporters
  • acidic amino aciid transporters
  • proline transporter
57
Q

Are amino acid transporters Na+ dependent transporters

A

yes

58
Q

How is the process of absorbing amino acids into the intestnial epithelial cells active and facilitated

A

because ATP is used to pump sodium out of the cell and build the sodium gradient. then sodium brings the amino acids into the cell by going down sodium’s concentration gradient into the cell

59
Q

Is the process of taking amino acids from the intestinal epithelial cells into the blood active or passive

A

passive (facilitated)

60
Q

What are the steps in getting amino acids into the blood from the lumen of the intestine

A
  1. Create a Na+ gradient with ATP and the sodium potassium pump
  2. use the sodium dependent amino acid transporter to get the amino acid into the cell
  3. then transport the amino acid into the blood through another transporter
61
Q

is NH4+ toxic

A

yes

62
Q

What are some of the complications of having excess NH4+

A
  • brain toxicity
  • interferes with the neurotransmitter glutamate
  • causes water retention in the brain
63
Q

What is the first two steps of getting rid of NH4+

A
  1. attach it to amino acids

2. carry it to the liver

64
Q

What happens to the Amino Acids with NH4+ that enter the liver from the diet

A
  1. they donate the NH4+ to PLP
  2. the amino acid portion leaves as a keto-acid
  3. the NH4+ is picked up by alpha-ketoglutarate
  4. alphaketoglutarate becomes glutamate
65
Q

How is ammonia transported in the blood

A

as glutamine

66
Q

how long can glutamine store NH3 groups

A

short term

67
Q

What happens to the alanine from muscle usage that comes to the liver with an NH4

A
  1. it gives the NH4 to alpha-ketoglutarate (making glutamate)
  2. The alanine becomes pyruvate
68
Q

so if alanine can donate NH4 to make glutamate and pyruvate is formed can glutamate donate NH4 to pyruvate to make alanine

A

yes

69
Q

When is alanine synthesized from glutamate and pyruvate

A

in anerobic conditions where pyruvate levels get high

70
Q

What happens to the alanine, that was synthesized from glutamate and pyruvate in the muscle, after it has been transported to the liver

A
  1. the liver turns the alanine back into pyruvate (creating glutamate in the liver)
  2. the pyruvate is used in gluconeogenesis to make glucose
  3. the glucose is sent back to the working muscle
  4. glycolysis occurs providing energy
71
Q

What does Glutamine do when it comes to NH4

A

it transports it to the liver

72
Q

What is the difference between glutamine and glutamate

A

glutamine has one NH4 group, Glutamate carries 2 NH4 groups

73
Q

What is the only enzyme (in amino acid metabolism) that uses both NADH and NADPH

A

glutamate dehydrogenase

74
Q

What are the reasons that glutamate dehydrogenase will use both NADH and NADPH

A
  1. because at certain times proteins will be degraded (NADH) and other times proteins will be built (NADPH)
  2. also because it’ll use any energy source to get rid of NH4
75
Q

What does the glutamate dehydrogenase do

A

it takes glutamate and uses NAD(P) to remove the NH4 group resulting in NH4 and alphaketoglutarate

76
Q

Where does the glutamate dehydrogenase reaction occur

A

in the mitochondrial matrix

77
Q

What is the diagnostic value of plasma aminotransferases

A

elevated plama aminotransferases means that there is cellular damage (because they are intracellular enzymes)

78
Q

what sort of damage does high plasma levels of aminotransferases indicate

A
  1. liver disease
  2. Heart attack
  3. viral hepatitis
  4. muscle disorders
79
Q

What are the two main carriers of NH4+

A

glutamine and glutamate

80
Q

What happens to the glutamine (non-liver tissues) and Glutamate (liver)

A

They go to the mitochondria to get rid of their NH4+

81
Q

What happens to glutamine in the mitochondria

A

it gets rid of one NH4+ (glutaminase) and becomes glutamate

82
Q

What happens to glutamate in the mitochondria

A

it gets rid of its NH4 and becomes alpha-ketoglutarate

83
Q

Where does the NH4 from glutamine go

A

into the mitochondial matrix

84
Q

where does the NH4 from glutamate go

A

either into the mitochondrial matrix, or it is transferred to oxaloacetate which is then converted into aspartate (which has the NH4

85
Q

what happens to the aspartate that takes the NH4 from glutamate

A

it goes down and is a cofactor/substrate in the urea cycle

86
Q

What happens to the NH4 released by glutamine and glutamate into the mitochondrial matrix

A

it is converted into carbamoyl phosphate

87
Q

what enzyme catalyzes the synthesis of carbamoyl phosphate and what are the necessary substrates

A

carbamoyl phosphate synthetase 1

it uses 2 ATP, bicarbonate, and NH4

88
Q

what does the carbamoyl phosphate go on and do after it has been synthesized

A

it goes and reacts with ornithine to create citrulline

89
Q

What does the citrulline in the mitochondria go and do

A

it leaves the mitochondria and begins the urea cycle

90
Q

What are the intermediates in the urea cycle

A
  1. Citrullline (in mitochondia)
  2. Citrulline (in cytosol)
  3. Citrullyl-AMP intermediate
  4. Aspartate (the one that took NH4 from glutamate)
  5. Argininosuccinate (aspartate + citrullyl AMP)
  6. Arginine
  7. Fumarate (argininosuccinate breaks down into arginine and fumarate
  8. Ornithine (in cytosol)
  9. Urea (arginine breaks down into ornithine and urea)
  10. Ornithin (in mitochondria)
91
Q

What happens with the fumarate created by the urea cycle

A

it can go back into the mitochondria to be converted into oxaloacetate

DMD 5242 (10 decks)

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