Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biochemistry > Biosynthesis of Amino Acids L7 > Flashcards

Biosynthesis of Amino Acids L7 Flashcards

1
Q

what happens in the nitrogen cycle

A

Nitrogen assimilation
Nitrogen in atmosphere fixed in soil
Some plants have special root nodules that fix nitrogen
Nitrogen transferred to several compounds in plant
Animals eat plant and receive nitrogen
Plants and animals die, nitrogen returned to soil
Bacterias in soil break apart nitrogen compounds and release into atmosphere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is NH4+

A

ammonium salt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is NO2-

A

nitrite

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what is NO3-

A

nitrate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what happens in the global nitrogen cycle - terrestrial biotic community

A

Nitrogen in atmosphere fixed by bacteria attached to plants in nodules
Transform nitrogen into ammonium salt
Ammonium salt oxidised to nitrite
Nitrite oxidised to nitrate
Nitrate used by plants (plants die and return nitrogen)
Denitrifying bacteria convert nitrate to nitrogen gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what happens in global nitrogen cycle - aquatic biotic community

A

Some nitrate into seas – runoff
Cyanobacteria fixing nitrogen in ocean convert nitrogen gas to ammonium salt
Ammonium salt to nitrate which feeds phytoplankton
phytoplankton feed fish
fish decompose free ammonium
Denitrifying bacteria convert nitrate to nitrogen gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

how can plants visibly show nitrogen deficiency

A

Yellow older leaves beneath green ones on top – nitrogen deficient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is the incorporation of nitrogen into living organisms

A

biochemically difficult in terms of energy and complexity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the percentage of carbon in living dry matter

A

50%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the percentage of oxygen in living dry matter

A

30%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the percentage of hydrogen in living dry matter

A

3%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the percentage of nitrogen in living dry matter

A

9%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what happens in the industrial nitrogen fixation

A

ammonia –> nitrites –> nitrates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what happens in biotic nitrogen fixation

A

protein (plants and microbes) decay and animal protein –> ammonia –> nitrites –> nitrates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

how is nitrogen fixed into naturally

A

Lightning can fix nitrogen gas – deposition of nitrates into soil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

why is nitrogen hard to assimilate

A

Nitrogen triple bond is extremely stable, so very difficult to break

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is nitrogen gas like

A

inert and difficult to incorporate into living organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what are the main producers / procedures to fix nitrogen of ammonia and ammonium salts

A

microorganisms 67%
lightning 10%
industry 23%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

how does industry make ammonia

A

haber process

N2 + H2 –> NH3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what does the Haber process require

A

High pressure 300 atm
High temperature 500°C
Fe catalyst

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what happens in industrial fixation

A

nitrogen from air distillation and hydrogen from methane + steam
N2+H2 form ammonia (NH3)
NH3 forms nitric acid which forms nitrates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what are the nitrate products of industrial fixation

A

plastics
explosives
fertiliser

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

how does nitrogen fixation occur

A

symbiotic bacteria live in root nodules of plants (legumes) and exchange NH4+ for carbohydrate precursors and a supply of leghaemoglobin maintains anaerobic conditions, as O2 inactivates nitrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what does nitrogenase do

A

catalyses a redox reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

how is nitrogen reduced to ammonia

A

Electrons flow from ferredoxin to reductase (iron protein) to nitrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what drives conformational change

A

ATP hydrolysis within reductase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

how do microorganisms fix nitrogen

A

eight high-potential electrons come from reduced ferredoxin, generated by photosynthesis or oxidative processes
Two molecules of ATP are hydrolyzed for each electron transferred
at least 16 molecules of ATP are hydrolyzed for each molecule of N2 reduced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what is nitrogenase

A

heterotetramer made of two α subunits and two β subunits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what is the nitrogen-reduction site

A

FeMo cofactor contains an open centre that is likely site of nitrogen binding and reduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

what are microbial nitrogenases for

A

complex enzymes that reduce N2 to NH4+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what is needed in the inversion process of nitrates to nitrites

A

nitrate reductase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

what is needed in the inversion process of nitrites to ammonia

A

nitrite reductase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

what are the main goals of nitrogen fixation

A

transfer nitrogen fixing genes to non-leguminous plants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

ammonium salt examples

A

sulphide and chloride

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

what happens in conversion of ammonium salt to amino acids

A

Use ammonium salt, alpha-ketoglutarate and lots of energy

Need to form glutamate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

what is alpha-ketoglutarate used in

A

krebs cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

how is glutamate synthesised

A

Glutamate is synthesized from NH4+ and alpha-ketoglutarate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

what aids ammonium salts to amino acids

A

glutamate dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

what happens in glycolysis

A

glucose is broken down into pyruvate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

what happens in krebs cycle

A

Pyruvate forms acetyl-CoA, CO2 and NADH molecule
Acetyl-CoA enters Krebs cycle (in mitochondrion)
Acetyl-CoA transferred to a 4 carbon molecule to 6 carbon compound
CoA molecule released
CO2 released forming a 5 carbon compound (NAD+ –> NADH)
4 carbon molecule made as NADH, CO2 and ATP made
Original 4 carbon molecule regenerated as NADH and FADH2 are formed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

how many times does the krebs cycle happen to remove glycolysis products

A

Krebs cycle happens twice to break down the two pyruvate molecules made in glycolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

where are most of intermediate products are derived from

A

krebs cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

what do alpha-ketoglutarate and ammonium salt form

A

intermediate compound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

where does the ammonium salt bind to when forming amino acids

A

bind to C=O, remove O

45
Q

what does glutamate dehydrogenase do

A

protonated Schiff base is reduced by transfer of a hydride ion from NADPH to form glutamate

46
Q

what does Glutamate dehydrogenase do

A

puts first nitrogen on

47
Q

what does Glutamine synthetase do

A

puts second nitrogen on

48
Q

where are glutamate dehydrogenase and glutamine synthetase found

A

present in all organisms

most prokaryotes also contain an evolutionarily unrelated enzyme, glutamate synthase

49
Q

what drives amidation

A

hydrolysis of ATP

50
Q

what happens to the second ammonium ion in biosynthesis of amino acids

A

incorporated into glutamate to form glutamine by action of glutamine synthetase

51
Q

how is glutamine formed

A

ATP phosphorylates side chain of glutamate, form an acyl-phosphate intermediate, reacts with ammonia to form glutamine

52
Q

what is an allosteric enzyme

A

Glutamine synthetase is a highly regulated ‘allosteric’ enzyme in bacteria

53
Q

what dictates rate of reaction

A

rate of reaction of ‘ordinary’ enzymes is largely dictated by concentration of substrate

54
Q

what do allosteric enzymes respond to

A

levels of activators and inhibitors

55
Q

why is glutamine important

A

nitrogen source to form many things such as histidine purines, pyrimidines and tryptophan

56
Q

what happens if end products e.g. histidine purines, pyrimidines and tryptophan made excessively

A

act as allosteric inhibitors - conformational change which will stop enzyme producing more glutamine
inhibit reaction to make glutamine
Pathway shut down when is not needed as has enough – feedback inhibitors

57
Q

what enzymes are necessary for initial steps of ammonium salts –> amino acids

A

Glutamate dehydrogenase and Glutamine Synthase

58
Q

what is the problem with ammonium salts

A

toxic

59
Q

what drives the formation of asparagine from aspartate

A

ATP hydrolysis

60
Q

what drives the formation of glutamine from glutamate

A

ATP hydrolysis

61
Q

what is the nitrogen donor for asparagine

A

glutamine

62
Q

what is glutamate a precursor of

A

glutamine, proline, arginine and main ‘N’ donor for other amino acids

63
Q

what is serine important for

A

can lead to production of many different molecules

64
Q

how are different amino acids formed

A

Depending on what ‘starting material’ you have can form different amino acids

65
Q

what can pyruvate form

A

alanine
valine
leucine

66
Q

what is the production of amino acids like

A

multi step biosynthetic system

Metabolic precursor will instruct the Biosynthetic family

67
Q

what is a co-factor

A

Enzyme is not functional unless something else is attached to it

68
Q

what do tranaminases require

A

co-factor PYRIDOXAL PHOSPHATE

69
Q

what is formed when an amino group added to oxaloacetate and pyruvate

A

Aspartate and alanine

70
Q

what is pyridoxal phosphate

A

a temporary ‘holder’ of nitrogen

Conveys nitrogen to other molecules

71
Q

what is PMP

A

pyridoxamine phosphate

72
Q

what happens when a carbon is added to molecule - S-Adenosylmethionine

A

SAM donates methyl group
When SAM donates a methyl group forms homocysteine
Reforms a methyl again
Repeats in a cycle

73
Q

what happens when a carbon is added to molecule - Tetrahydrofolate

A

Mammals synthesise pteridine ring, unable to conjugate it to the other two units. They obtain tetrahydrofolate from their diets or from microorganisms in their intestinal tracts

74
Q

How does deoxyribose monophosphate (dUMP) and deoxyribose monophosphate (dTMP) differ

A

deoxyribose monophosphate dtMP has a methyl group

75
Q

how can some synthesis reactions still occur even if enzyme is mutated

A

various cascades to reach same end product, therefore more than one enzyme can do job
If there is a mutation in an enzyme the other enzyme can still produce the product

76
Q

what is amino acid catabolism

A

degradation
too much amino acids does not frequently happen as require a lot of energy to make amino acids
Highly regulated as when start to make too much – allosteric inhibition

77
Q

examples of specific protein degradation

A

ubiquitin system

78
Q

what is most of the cellular energy consumed in

A

95% of cellular ‘energy’ in animals is consumed by protein biosynthesis

79
Q

what energy is recovered from protein breakdown

A

very little ‘energy’ is recovered by protein breakdown

80
Q

what is gluconeogenesis

A

generation of glucose from non-carbohydrate carbon substrates such as lactate

81
Q

what happens in amino acid catabolism

A

amino acid broken to form useful carbon skeletons and unwanted NH4

82
Q

what is the major site of amino acid degradation in mammals

A

liver

83
Q

are amino acids part of the krebs cycle

A

Certain amino acids broken and get into krebs cycle

84
Q

how does the krebs cycle make glucose

A

Krebs cycle assimilate broken down carbon skeleton and make glucose

85
Q

what is the strategy of amino acid degradation

A

transform carbon skeletons into major metabolic intermediates that can be converted into glucose or oxidized by krebs cycle

86
Q

what ate ketogenic amino acids

A

Amino acids that are degraded to acetyl CoA or acetoacetyl CoA

87
Q

what do ketogenic amino acids make

A

they can give rise to ketone bodies or fatty acids

88
Q

what are glucogenic amino acids

A

amino acids that are degraded to pyruvate, alpa-ketoglutarate, succinyl CoA, fumarate, or oxaloacetate

89
Q

what is the first step of amino acid catabolism

A

removal of unwanted NH4

90
Q

what catalyses the removal of NH4

A

aminotransferases and glutamate dehydrogenase

91
Q

what is ammonotelic

A

ammonium as final product

92
Q

what is Uricotelic

A

uric acid as final product

93
Q

what is Ureotelic

A

urea as final product

94
Q

how is excess nitrogen removed

A

excreted as urea

integration of nitrogen metabolic and Urea cycle

95
Q

what is the second step in amino acid catabolism

A

the urea cycle

96
Q

what is some of the NH4+ formed in the breakdown of amino acids used in

A

consumed in the biosynthesis of nitrogen compounds

97
Q

where does the urea cycle occur

A

cytoplasm and inside mitochondria

98
Q

what processes are Metabolic Integration of Nitrogen Metabolism

A

urea cycle

krebs cycle

99
Q

how are the urea and krebs cycle linked

A

transamination of oxaloacetate are linked by fumarate and aspartate

100
Q

what percent of amino acids are reused

A

About 75% of liberated AA are reutilised

101
Q

what percentage os body proteins do humans turn over

A

each day 1-2%

102
Q

what happens to amino acids that are not immediately incorporated into new proteins

A

rapidly degraded

103
Q

where is urea mainly excreted

A

through kidney in urine

some transported to intestine

104
Q

where is ammonia released, how is it removed

A

Ammonia release at intestine goes back to liver for reconversion to urea

105
Q

when is lactate formed

A

made in muscles when ATP demand exceeds capacity of oxidative phosphorylation

106
Q

what happens when lactate is formed

A

Lactate is then circulated through blood to liver where lactate is converted to glucose
Glucose feeds the muscle

107
Q

does all amino acids degradation occur in liver

A

no

muscles lack urea cycle

108
Q

what are amino acids used in

A

Feedback into the Krebs cycle+ glycolysis
Backbone of many other important biomolecules
Nitric Oxide biosynthesis

109
Q

why are amino acids important

A

precursors of many important Biomolecules

Biochemistry (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions