Nitrogen

Question 1

Nitrogen fixing requires

Answer 1

nitrogenase

lots of energy

Question 2

nitrogenase is inactivated by

Answer 2

oxygen

Question 3

Leguminous plants produce leghemoglobin which binds O2 allowing the concentration to be…

Answer 3

low enough to allow nitrogenase to work

Question 4

nitrogen fixation produces

Answer 4

ammonia

Question 5

once ammonia is fixed it is converted into ……..

a usable form of nitrogen taken up by plants and microbes

Answer 5

nitrate

Question 6

Flow of nitrogen from ammonia to other biomolecules occurs through

Answer 6

glutamate

eg Urea

Question 7

Transamination

Answer 7

transferring amino groups between different molecules

in order to conserve nitrogen

Question 8

a chemical reaction that transfers an amino group to a ketoacid to form new amino acids.

Answer 8

transamination

Question 9

aminotransferases

Answer 9

intracellular enzymes

Question 10

glutamate can only ‘lose’ nitrogen by

Answer 10

transamination

Question 11

Humans excrete nitrogen as

Answer 11

urea and uric acid

Question 12

Ammonia is transported in the bloodstream safely as

Answer 12

glutamate

Question 13

Glutamate can donate ammonia to ………. to make …………

Answer 13

pyruvate

alanine

(or can be made into glutamine)

Question 14

Glycolysis yields

Answer 14

pyruvate

if not eliminated LACTIC ACID will build up

Question 15

excess pyruvate can be converted to………. for transport to the

Answer 15

alanine

liver

Question 16

what charge does glutamate have?

Answer 16

negative

-ve

Question 17

what charge do alanine and glutamine have?

Answer 17

no charge

Question 18

charged molecules don’t pass through membranes so easy - they have to be converted to

Answer 18

uncharged molecules

Question 19

Catabolism of amino acids involves transfer of the amino group via PLP-dependent aminotransferase to a donor such as………. to yield

Answer 19

alpha-ketoglutarate

glutamine

Question 20

toxic ammonia is quickly recaptured into carbamoyl phosphate and passed into

Answer 20

the urea cycle

Question 21

L-glutamine can be used to create new …………. or it can dispose of……..

Answer 21

amino acids

excess nitrogen via ammonia

Question 22

Most inherited metabolic disorders are

Answer 22

autosomal recessive inheritance

Question 23

there are ….. inherited disorders of the urea cycle

Answer 23

6

Question 24

urea cycle defects are most common in ………………… deficiency

Answer 24

ornithine transcarbamoylase (OTC)

Question 25

OTC has …………. inheritance

Answer 25

x - linked

Question 26

Phenylketonuria

Answer 26

absence of phenylalanine hydroxylase (PAH)

increased phenylalanine levels

Question 27

Phenylketonuria treatment

Answer 27

low protein diet supplemented with protein substitute