nitrogen metabolism

Question 1

Where do we get nitrogen?

Answer 1

Plants and Animals

Question 2

How do we get nitrogen from plants?

Answer 2

obtained from nitrogen-fixing bacteria (N2 to NH3)

Question 3

Do plants use amino acids for energy?

Answer 3

no

Question 4

How do we get nitrogen from animals?

Answer 4

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

Question 5

What are the enzymes to break down dietary proteins?

Answer 5

Pepsin and zymogens

Question 6

Where is pepsin found?

Answer 6

in stomach

Question 7

Where are zymogens released?

Answer 7

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

Question 8

What are the three zymogens from the pancreas?

Answer 8

Trypsinogen, Chymotrypsinogen, and Procarboxypeptidase

Question 9

What is the pro-form of pepsin?

Answer 9

Pepsinogen

Question 10

What are the three cleaved active zymogens?

Answer 10

trypsin, chymotrypsin, and carboxypeptidase

Question 11

What do ketogenic amino acids enter the TCA cycle as?

Answer 11

acetyl coA

Question 12

What do glucogenic amino acids enter the TCA cycle as?

Answer 12

oxaloacetate

Question 13

What are the true ketogenic amino acids?

Answer 13

leucine, lysine

Question 14

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

Answer 14

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

Question 15

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

Answer 15

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

Question 16

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

Answer 16

phenylalanine and tyrosine
glucogenic

Question 17

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

Answer 17

Isoleucine, methionine, threonine, and valine
Glucogenic

Question 18

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

Answer 18

arginine, glutamine, histidine, and proline
Glucogenic

Question 19

What is an ammonotelic and an example of an organism?

Answer 19

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

Question 20

What is a ureotelic and an example of an organism?

Answer 20

Organism that excretes urea
example: humans and sharks

Question 21

What is a uricotelic and an example of an organism?

Answer 21

Organism that excretes uric acid
example: birds and reptiles

Question 22

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

Answer 22

glutamate

Question 23

Where does the processing of ammonia to products primarily occur?

Answer 23

In the liver

Question 24

What is the role of Glutamine?

Answer 24

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

Question 25

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

Answer 25

glutamate

Question 26

What facilitates the transfer of oxygen group to ammonia group?

Answer 26

glutamine synthetase

Question 27

What inhibits glutamine synthetase?

Answer 27

Alanine, Glycine, AMP, and Carbamoyl Phosphate

Question 28

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

Answer 28

alanine aminotransferase

Question 29

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

Answer 29

alanine aminotransferase

Question 30

What coenzyme does aminotransferase need?

Answer 30

PLP (pyridoxal phosphate) form of a vitamin B6

Question 31

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

Answer 31

glutamate dehydrogenase

Question 32

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

Answer 32

carbamoyl phosphate synthetase I

Question 33

How many ATP to make carbamoyl phosphate?

Answer 33

2 ATP

Question 34

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

Answer 34

Krebs Bicycle - Aspartate-argininosuccinate shunt

Question 35

What is the function of the malate aspartate shuttle?

Answer 35

regenerate NADH in the mitochondira

Question 36

What is the main point of regulation in the Urea Cycle

Answer 36

N-Acetylglutamate

Question 37

Regulation of the Urea cycle with fasting?

Answer 37

protein breakdown

Question 38

Regulation of the Urea cycle with High protein diet?

Answer 38

extra nitrogen decomposed & excreted

Question 39

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

Answer 39

Albinism

Question 40

What is the defective enzyme of Albinism?

Answer 40

Tyrosine 3-monooxygenase

Question 41

What are the symptoms of Albinism?

Answer 41

Lack of pigmentation; white hair, pink skin

Question 42

What defect is the defective process of urea synthesis?

Answer 42

Carbamoyl phosphate synthetase I deficiency

Question 43

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

Answer 43

carbamoyl phosphate synthetase I

Question 44

What are the symptoms of carbamoyl phosphate synthetase I deficiency?

Answer 44

lethargy; convulsions; early death

Question 45

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

Answer 45

Maple syrup urine disease

Question 46

What is the defective enzyme of maple syrup urine disease?

Answer 46

branched-chain a-keto acid dehydrogenase complex

Question 47

What are the symptoms are maple syrup urine disease?

Answer 47

vomiting; convulsions; intellectual disability; early disease

Question 48

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

Answer 48

Phenylketonuria

Question 49

What is the defective enzyme of phenylketonuria?

Answer 49

phenylalanine hydroxylase

Question 50

What are the symptoms of phenylketonuria?

Answer 50

neonatal vomiting; intellectual disability

Question 51

What are alternative pathways for nitrogen excretion?

Answer 51

treat with benzoate and/or phenylbutyrate

Question 52

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

Answer 52

glycine 1 nitrogen

Question 53

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

Answer 53

glutamine 2 nitrogens

Question 54

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

Answer 54

build up of a-keto acids and loss of nitrogens

Question 55

What does phenylalanine hydroxylase mediate?

Answer 55

The transfer of and OH from phenylalanine to make tyrosine

Question 56

What pathway requires extensive e- transfers?

Answer 56

Nitrogen fixation

Question 57

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

Answer 57

16 ATP

Question 58

What is the starting transfer in the fixation of nitrogen?

Answer 58

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

Question 59

What is the end transfer in the fixation of nitrogen?

Answer 59

N2 + 2H to 2NH4 + H2

Question 60

Amino acid synthesis summarized?

Answer 60

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

Question 61

Can animals synthesize essential amino acids?

Answer 61

NO