lecture 10

Question 1

what is nitrogen

Answer 1

critical part of amino acids and nucleotides

Question 2

nitrification by soil bacteria

Answer 2

oxidative process

Question 3

denitrification

Answer 3

anaerobic process

Question 4

nitrogen fixation by some bacteria

Answer 4

reduction of atmos N2

Question 5

N2 + 10H+ +8e- +16 ATP

Answer 5

2NH4+ + 16 ADP +H2

Question 6

per e

Answer 6

2 ATP peer cycle

Question 7

2 ATP binding

Answer 7

shifts reduction potential

Question 8

clusters of

Answer 8

Fe-S

Question 9

iron Molybdenum

Answer 9

cofactor for nitrogenase

Question 10

8 electrons

Answer 10

6 for N2, 2 for H2

Question 11

nitrogenase

Answer 11

perfoms nitrogen fixation

Question 12

plant derived leghemoglobin

Answer 12

Oxygen toxicity to bacterial nitrogenase

Question 13

glutamine synthetase

Answer 13

Catalyzes assimilation of NH4+ into glutamate to yield glutamine

Question 14

how many subunits does glutamine synthetase have

Answer 14

12 identical subunit active sites

Question 15

how does regulation of nitrogen metabolism occur

Answer 15

allosteric regulation
covalent modification

Question 16

allosteric regulation

Answer 16

Ala, Gly, etc. are allosteric inhibitors of enzyme. All 8 molecules needed to effectively block enzyme activity. .

Question 17

what do adjustments of glutamine react to

Answer 17

immediate metabolic requirements

Question 18

covalent modification

Answer 18

adenylation of enzyme tyrosine residue (Tyr397)

Question 19

adenylation

Answer 19

covalent, inhibitory

Question 20

AT

Answer 20

Adenylyltransferase

Question 21

Uridylyation of Tyr(PII-UMP)

Answer 21

stimulates deadenylation

Question 22

amino acid carbon skeletons are derived from

Answer 22

glycolysis
TCA
pentose phosphate pathway

Question 23

for pathways

Answer 23

know key precursors &
intermediates that give rise to specific
AA synthesized

Question 24

alpha-ketogluterate

Answer 24

glutamate
glutamine
proline
arginine

Question 25

pyruvate

Answer 25

alanine valine leucine isoleucine

Question 26

3-phosphoglycerate

Answer 26

serine glycine cysteine

Question 27

phosphoenolpyruvate/erythrose 4-phosphate

Answer 27

tryptophan phenylalanine tyrosine

Question 28

oxaloacetate

Answer 28

aspartate asparagine methionine threonine lysine

Question 29

ribose 5-phosphate

Answer 29

histidine

Question 30

allosteric regulation of isoleucine

Answer 30

feedback inhibition

Question 31

threonine dehydratase

Answer 31

inhibited by end product by isoleucine

Question 32

coordinated regulatory mechanisms in eColi

Answer 32

have aspartate as precursor

Question 33

isozymes

Answer 33

can have or not have allosteric regulation

Question 34

fates of amino group and carbon skeleton

Answer 34

take separate but interconnected paths

Question 35

fate of amino group nitrogen

Answer 35

removed from AA by aminotransferases to yield ammonia (nitrogen not used in energy-producing pathways)

Question 36

fate of rest of carbon skeleton of AA

Answer 36

enter metabolic pathways as precursors of glucose or Krebs cycle intermediates.

Question 37

In many aminotransferase reactions

Answer 37

a-ketoglutarate is the amino group acceptor

Question 38

all aminotransferases have

Answer 38

pyridoxal phosphate as a cofactor

Question 39

fate of ammonium ions

Answer 39

Some used in synthesis of nitrogen compounds (amino acids, nucleotides)

Question 40

excess ammonium ions converted into

Answer 40

ammonia, urea, or uric acid (depends on organism) and then excreted

Question 41

what do we derive a small amount of from catabolism of amino acids

Answer 41

oxidative energy

Question 42

what are amino acids derived from

Answer 42

breakdown of cellular proteins, ingested proteins, & body proteins (when other forms of fuel aren’t available)

Question 43

what do proteins degrade

Answer 43

ingested proteins in stomach & small intestine

Question 44

early step in catabolism

Answer 44

separation of amino group from carbon skeleton

Question 45

amino group transferred to a-ketoglutarate

Answer 45

to form glutamate (REquires PLP)

Question 46

Ammonia from other tissues transported to liver as

Answer 46

1) amide nitrogen of glutamine 2) amino group of alanine (from skeletal muscle)

Question 47

pyruvate can be produced by

Answer 47

deamination of alanine (liver)

Question 48

pyruvate produced by deamination of alanine

Answer 48

is converted to glucose ( transported back to muscle)

Question 49

glucose-alanine cycle

Question 50

amino group catabolism

Answer 50

depends on the organism NH4 is excreted in different forms

Question 51

urea cycle

Answer 51

Arginine to ornithine to citruline to arginosuccinate carbomoyl phosphate enters right before citruline aspartate enters right before arginosuccinate numerate exits after argininosuccinate urea is produces when water enters after arginine

Question 52

aspartate- argininosuccinate shunt

Answer 52

links urea to krebs

Question 53

fumerate from urea cycle

Answer 53

becomes malate which enters the Krebs

Question 54

what does alanine serve as

Answer 54

a carrier of ammonia & a carbon skeleton of pyruvate from skeletal muscle to the liver

Question 55

pyruvate produced by deamination of alanine

Answer 55

is converted to glucose

Question 56

ammonia

Answer 56

is excreted

Question 57

phenylketonuria

Answer 57

defective process- conversion of phenylalanine to tyrosine

Question 58

phenylalanine hydroxylase

Answer 58

error in this enzyme cause phenylketonuria

Question 59

Ammonia

Answer 59

most aquatic vertebrates, such as bony fishes and the larvae of amphibia

Question 60

urea

Answer 60

many terrestrial vertebrates, also sharks

Question 61

uric acid

Answer 61

birds, reptiles