module 12- amino acid synthesis

Question 1

what is the endpoint of nitrogen fixation

Answer 1

ammonium

Question 2

glutamate dehydrogenase

Answer 2

a-ketoglutarate -> glutamate

Question 3

glutamine synthetase

Answer 3

glutamate -> glutamine

Question 4

glutamate synthase

Answer 4

a-ketoglutarate -> 2 glutamate

Question 5

what is the regulatory enzyme of nitrogen metabolism

Answer 5

glutamine synthetase

Question 6

T or F: glutamine synthetase is present in all organisms

Answer 6

T

Question 7

ubiquitous enzyme

Answer 7

present in all organisms

Question 8

how is glutamine synthetase regulated (2)

Answer 8

covalent modification & allosterically

Question 9

how many allosteric inhibitors? how many come from glutamine and how many from amino acids

Answer 9

8 total, 6 from glutamine & 2 from amino acids

Question 10

concerted inhibition

Answer 10

effects are more than additive

Question 11

allosteric inhibitors are ( ) inhibition

Answer 11

concerted

Question 12

covalent modification of glutamine synthetase

Answer 12

adenylylation

Question 13

adenylylation

Answer 13

linking AM to tryosine

Question 14

glutamine synthetase is a ( ) structure

Answer 14

quaternary & has multiple subunits which each have an active site

Question 15

consequence of adenylylation

Answer 15

insensitive to allosteric inhibitors, need combination of covalent & allosteric to control activity

Question 16

SAM

Answer 16

adds methyl groups

Question 17

why is SAM used over methione?

Answer 17

methionine is not very reactive

Question 18

methyl groups are almost always transferred to a ( ) or ( ) atom

Answer 18

nitrogen or oxygen

Question 19

N-methyltransferase

Answer 19

SAM transfers nitrogen to norepinephrine

Question 20

what is tetrahydrofolate derived from

Answer 20

vitamin B9 (folate)

Question 21

what does N5 & N10 indicate?

Answer 21

indicate specific atoms in tetrahydrofolate to which carbons are attached

Question 22

source of one-carbon units

Answer 22

serine or formate, oxygen, nitrogen

Question 23

T or F: tetrahydrofolate is a carrier of very diverse types of one-carbon units

Question 24

aspargaine synthetase

Answer 24

aspartate -> asparagine

Question 25

T or F: both glutamine & glutamate act as amino group donors at different steps of the synthetic pathway for histidine in plants

Answer 25

T

Question 26

what 3 metabolic pathways supply the intermediates that amino acids are synthesized from?

Answer 26

glycolysis, pentose phosphate, CAC

Question 27

conditionally essential amino acids

Answer 27

essential only during specific points

Question 28

what are the 5 non-essential amino acids

Answer 28

alanine, asparagine, aspartate, glutamate & serine

Question 29

what amino acids can be derived from oxaloacetate

Answer 29

aspartate, asparagine, methionine, lysine, & threonine

Question 30

what amino acids can be derived from pyruvate

Answer 30

alanine, valine, leucine & isoleucine

Question 31

what is used as an amino group donor in lysine pathway

Answer 31

glutamate

Question 32

product inhibition

Answer 32

end product acts as allosteric inhibitor of 1st step

• prevents unnecessary production of F when levels are sufficient

Question 33

sequential inhibition

Answer 33

branched into 2 end points, F & G inhibit 1st committed step

F & G inhibit the conversion of C to D and E, and C acts back on A to B

Question 34

concerted inhibition

Answer 34

F & G inhibit A to B

Question 35

enzyme multiplicity

Answer 35

2 isoenzymes are inhibited by F or G

allows fine tuning

Question 36

what 2 molecules provide entry points for the assimilation of ammonium into biomolecules

Answer 36

glutamine & glutamate

Question 37

what process does glutamate donates its amino groups for the synthesis of other amino acids?

Answer 37

transamination

Question 38

what 2 molecules provide 1 carbon units for the synthesis of biomolecules

Answer 38

tetrahydrofolate derivatives & SAM

Question 39

oxaloacetate is a direct precursor for which animo acid?

Answer 39

aspartate