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biochem exam 4 > nitrogen metabolism > Flashcards

nitrogen metabolism Flashcards

1
Q

Where do we get nitrogen?

A

Plants and Animals

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2
Q

How do we get nitrogen from plants?

A

obtained from nitrogen-fixing bacteria (N2 to NH3)

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3
Q

Do plants use amino acids for energy?

A

no

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4
Q

How do we get nitrogen from animals?

A

Carnivores, Herbivores, and Cellular proteins (amino acid catabolism)

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5
Q

What are the enzymes to break down dietary proteins?

A

Pepsin and zymogens

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6
Q

Where is pepsin found?

A

in stomach

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7
Q

Where are zymogens released?

A

released from exocrine cells in pancreas and get processed into active proteases

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8
Q

What are the three zymogens from the pancreas?

A

Trypsinogen, Chymotrypsinogen, and Procarboxypeptidase

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9
Q

What is the pro-form of pepsin?

A

Pepsinogen

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10
Q

What are the three cleaved active zymogens?

A

trypsin, chymotrypsin, and carboxypeptidase

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11
Q

What do ketogenic amino acids enter the TCA cycle as?

A

acetyl coA

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12
Q

What do glucogenic amino acids enter the TCA cycle as?

A

oxaloacetate

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13
Q

What are the true ketogenic amino acids?

A

leucine, lysine

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14
Q

What amino acids enter as acetyl-coA and what is their classification?

A

leucine, lysine, phenylalanine, tryptopahn, tyrosine, isoleucine, and threonine
Ketogenic Amino acids

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15
Q

What amino acids enter as oxaloacetate and what is their classification?

A

alanine, cysteine, glycine, serine, threonine, and tryptophan, asparagine, and aspartate
Glucogenic

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16
Q

What amino acids enter as fumarate and what is their classification?

A

phenylalanine and tyrosine
glucogenic

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17
Q

What amino acids enter as Succinyl-coA and what is their classification?

A

Isoleucine, methionine, threonine, and valine
Glucogenic

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18
Q

What amino acids enter as glutamate to a-ketoglutarate and what is their classification?

A

arginine, glutamine, histidine, and proline
Glucogenic

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19
Q

What is an ammonotelic and an example of an organism?

A

organism that excretes N2 in the form of ammonia
example: bony fish, except sharks

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20
Q

What is a ureotelic and an example of an organism?

A

Organism that excretes urea
example: humans and sharks

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21
Q

What is a uricotelic and an example of an organism?

A

Organism that excretes uric acid
example: birds and reptiles

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22
Q

What is the primary intermediate amino acid before entering the urea cycle

A

glutamate

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23
Q

Where does the processing of ammonia to products primarily occur?

A

In the liver

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24
Q

What is the role of Glutamine?

A

replaces the O- with ammonia group m(NH3), by removing acid acting properties of glutamate

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25
Q

What does not transport well in the blood due to the carboxyl R group?

A

glutamate

26
Q

What facilitates the transfer of oxygen group to ammonia group?

A

glutamine synthetase

27
Q

What inhibits glutamine synthetase?

A

Alanine, Glycine, AMP, and Carbamoyl Phosphate

28
Q

What facilitates the transfer of an amino group from glutamate onto pyruvate to give alanine?

A

alanine aminotransferase

29
Q

What facilitates the transfer from alanine onto a-ketoglutarate to glutamate and creates pyruvate?

A

alanine aminotransferase

30
Q

What coenzyme does aminotransferase need?

A

PLP (pyridoxal phosphate) form of a vitamin B6

31
Q

What enzyme removes ammonia from glutamate and releases a-ketoglutarate?

A

glutamate dehydrogenase

32
Q

What enzyme facilitates the addition of the ammonia group onto a carbon skeleton producing carbamoyl phosphate?

A

carbamoyl phosphate synthetase I

33
Q

How many ATP to make carbamoyl phosphate?

A

2 ATP

34
Q

What is the main connection between the Urea and TCA cycle?

A

Krebs Bicycle - Aspartate-argininosuccinate shunt

35
Q

What is the function of the malate aspartate shuttle?

A

regenerate NADH in the mitochondira

36
Q

What is the main point of regulation in the Urea Cycle

A

N-Acetylglutamate

37
Q

Regulation of the Urea cycle with fasting?

A

protein breakdown

38
Q

Regulation of the Urea cycle with High protein diet?

A

extra nitrogen decomposed & excreted

39
Q

What birth defect is the defective process of melanin synthesis from tyrosine?

A

Albinism

40
Q

What is the defective enzyme of Albinism?

A

Tyrosine 3-monooxygenase

41
Q

What are the symptoms of Albinism?

A

Lack of pigmentation; white hair, pink skin

42
Q

What defect is the defective process of urea synthesis?

A

Carbamoyl phosphate synthetase I deficiency

43
Q

What is the defective enzyme of Carbamoyl phosphate synthetase I deficiency?

A

carbamoyl phosphate synthetase I

44
Q

What are the symptoms of carbamoyl phosphate synthetase I deficiency?

A

lethargy; convulsions; early death

45
Q

What defect is the defective process of isoleucine, leucine, and valine degradation?

A

Maple syrup urine disease

46
Q

What is the defective enzyme of maple syrup urine disease?

A

branched-chain a-keto acid dehydrogenase complex

47
Q

What are the symptoms are maple syrup urine disease?

A

vomiting; convulsions; intellectual disability; early disease

48
Q

What is the defective process of the conversion of phenylalanine to tyrosine?

A

Phenylketonuria

49
Q

What is the defective enzyme of phenylketonuria?

A

phenylalanine hydroxylase

50
Q

What are the symptoms of phenylketonuria?

A

neonatal vomiting; intellectual disability

51
Q

What are alternative pathways for nitrogen excretion?

A

treat with benzoate and/or phenylbutyrate

52
Q

What amino acid is used with benzoate and how many nitrogens are excreted?

A

glycine
1 nitrogen

53
Q

What amino acid is used with Phenylbutyrate and how many nitrogens are excreted?

A

glutamine
2 nitrogens

54
Q

What is the build up and loss of molecules in maple syrup urine disease?

A

build up of a-keto acids and loss of nitrogens

55
Q

What does phenylalanine hydroxylase mediate?

A

The transfer of and OH from phenylalanine to make tyrosine

56
Q

What pathway requires extensive e- transfers?

A

Nitrogen fixation

57
Q

How many ATP are required per N2 molecule in Nitrogen fixation?

A

16 ATP

58
Q

What is the starting transfer in the fixation of nitrogen?

A

4 coA + 4 pyruvate to 4 CO2 + 4 acetyl-coA

59
Q

What is the end transfer in the fixation of nitrogen?

A

N2 + 2H to 2NH4 + H2

60
Q

Amino acid synthesis summarized?

A

Make carbon skeleton first, then transamination reaction to add amino group

61
Q

Can animals synthesize essential amino acids?

A

NO

biochem exam 4 (3 decks)

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