Topic 9

Question 1

nitrogen fixation

Answer 1

when atmospheric nitrogen is converted to a form that the body can use
turning N2 into something
ammonia is most usable form of nitrogen in the body
nh3+ NO3 N2

Question 2

nitrate utilization

Answer 2

reduction of NO3 into NH4
plants and fungi do this

Question 3

nitrogen economy

Answer 3

how organism maintain their nitrogen supply
organisms cannot store nitrogen

Question 4

protein turn over and degradtion

Answer 4

regulates protein levels and gets rid of damamged ones
each protein has its own metbaloic half life
varys depending on role of protein and the environment its in
things like enzymes, anitbodies etc have a short half life so their function can be abruptly stopped
structual proteins have a longer half life

Question 5

site of protein degradation

Answer 5

lysosome - and protease in cytosol

Question 6

signalling for protein breakdown

Answer 6

ubiquitination - ubiquinone is a protein that tags other proteins with a poryubiquinon chain
PEST sequennce - proteins with this sequence like enzymes, indicate that the protein should be broken down quickly
N-terminal residue - amino acids on the n-terminals also dictate their half life
Oxidation of amino acid residue - some AA are more suseptiable to oxidation - when this happens it dgerades them

Question 7

AA degradition

Answer 7

when theres too much protein amino acids are degraded in. two steps - amino group is removed and carbon skeleton is destroyed
1) removal of amino group - makes a-keto acid and ammonia - process is called transaminatino, a-keto acid is donated to glutarate which forms a-ketoglutarate which is used in the krebs cycle
2) ammonia detoxification

Question 8

ammonia detoxification

Answer 8

ammonia is a by-product of aa degradtion
is transported to the liver and is excreted as urea

Question 9

Biosynthesis of AA

Answer 9

1) transaminatinon reaction where amino acid to a-keto acid

Question 10

glutamate and derivatives

Answer 10

glutamate is converted to glutamic-asemialdehyde - which is a precourser for proline and ornithine

Question 11

collagen protein

Answer 11

gultamic-asemialdehyde - proline - hydroxyproline - collagen
needs vit c to do this - id theres a diffencey you get scruvy which is a connective tissue disorder

Question 12

ornithine

Answer 12

ornithine - arginine - urea

Question 13

biosynthesis of sulfur containing amino acids

Answer 13

methionine form diet - SAM - homocystiene - cysteine

Question 14

poryphorin biosynthesis

Answer 14

glycine reacts with succiynl-coa to form ALA and CO2
in plants this process is done with glutamate instead
- then two moles of ALA come together to form porphobilonogen
- four of these molecules bind together to form uroporphynigoen 111
-IRON is added via ferrrocheltase

Question 15

breakdown of heme

Answer 15

• heme ring breaks down
  -iron is removed
• converted to billirubin
  -transported to liver via albumin
  excreted into bile

Question 16

serotonin synthesis

Answer 16

tryptophan is hydroxylated then decarboxalted to form serotonin

Question 17

catecholamine synthesis

Answer 17

starts with tyrosine
is hydroxylated then decarboxylated to from dopa
dopa is converted to dopamine
dopamine is converted to NA and adredaline

Question 18

de novo synthesis

Answer 18

cells make nucliec acid from amino acids and sugars

Question 19

salvage pathway

Answer 19

cells building nucleotides from old degraded nucleotides