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Biochemistry > Nucleotide Biosynthesis L4 > Flashcards

Nucleotide Biosynthesis L4 Flashcards

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1
Q

what are the nucleotide biosynthesis function

A 
Precursors of RNA and DNA
Currency of energy
Activators of biosynthesis 
Signal transduction pathways
components of co-enzymes
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2
Q

what are the universal currencies of energies

A

ATP
GTP
NAD

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3
Q

what are the components of major coenzymes

A

NAD
FAD
CoA

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4
Q

what are the activated intermediates in biosynthesis

A

UDP-glucose

CDP-diacylglyverol

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5
Q

what are the essential components of signal-transduction pathway

A

cAMP
cGMP second messengers within and between cells
ATP = donor of phosphoryl groups by kinases

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6
Q

which are the purines

A

PUGA – purines are guanine and adenine

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7
Q

what are purines

A

double ring

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8
Q

which are the pyrimidines

A

Cytosine
Uracyl
Thymine

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9
Q

what are pyrimidines

A

single ring

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10
Q

which are the nitrogenous bases

A 
Adenine
Guanine
Cytosine
Uracil
Thymine
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11
Q

how does the name of a base change when a sugar is attached to it

A 
becomes a nucleoside
Adenosine
Guanosine
Uridine
Cytidine
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12
Q

how does the name of base change when a sugar and phosphate ester attached

A

Adenylate (ATP)
Guanylate (GTP)
Urydylate (UTP)
Cytidylate (CTP)

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13
Q

what is chemical energy for

A

For synthesis of complex biological molecules

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14
Q

what is transport energy

A

Cells often live in dilute environments

need to expend energy to transport that nutrient into the cell

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15
Q

what is mechanical energy for

A

cells may be able to change their physical location

all cells need to move structures (DNA replication, wound repair etc…) within them

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16
Q

What happens in electron transport in aerobic conditions

A

NADH donates two electrons to electron transport chain, NADH becomes NAD+
In the membrane electron passed through a series of different proteins
Electrons combine with oxygen and protons to form water, an additional proton is pumped across
Causes an imbalance in the cell – high proton concentration out of the cell – used to fuel ATP production

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17
Q

what is the redox couple reaction

A

NAD+ NADH

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18
Q

how is water formed in electron transport

A

NADH donates electron to oxygen to form water

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19
Q

Why is aerobic respiration the most efficient

A

Oxygen is at the bottom of the tower – further down tower, more energy released

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20
Q

What is an alternative electron acceptor

A

Nitrate

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21
Q

What is nitrate reduced to

A

NO2-, N2O, N2

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22
Q

what are some of the largest monomers

A

nucleotides

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23
Q

what does the nucleotide synthesis involve

Study These Flashcards
A

many steps and large amounts of energy

24
Q

what is the control of biosynthesis of nucleotides

Study These Flashcards
A

once have enough, will stop producing as don’t waste energy
need to make right amount of each base
too much is made, energy wasted, too little, DNA replication and cellular metabolism come to a halt
cell sensitive to presence of pre-made nucleotides in environment, down regulate de novo synthesis pathways use what is already present in surroundings

25
what are bacteria capable of
interconverting purines (adenine and guanine) and interconverting pyrimidines (thymidine, cytidine and uracil)
26
what is de novo
making from new
27
what is salvage
have got something already, saving it, taking something that was going to be destroyed
28
What does the synthesis of purine start with
PRPP
29
How is PRPP made in synthesis of purine
Ribose 5-phosphate + ATP | Two phosphates from ATP transferred to ribose 5-phosphate
30
What is PRPP also used in biosynthesis of
``` Purines Pyrimidines NAD histidine tryptophan ```
31
what does Purine synthesis start with
addition of an ammonia from glutamine to PRPP
32
what happens in the six steps of purine synthesis
five membered ring of purines in synthesised with a net cost of five ATP
33
what is the final product of de novo synthesis of purines
CAIR
34
What is CAIR converted to
IMP
35
How is CAIR converted to IMP
4 steps including use of ATP
36
How is GMP made from IMP
2 steps using one ATP
37
How does IMP and GMP differ
GMP adds an amino group (nothing removed off IMP)
38
Which are the central donors of amino groups in synthesis of everything
Glutamine and asparagine
39
What happens in the synthesis of purines
Add ATP C=O gains phosphate group Form first activated group React with anything as reactive due to phosphate Donor group e.g. HH3 reacts with it will form an intermediate group Lose phosphate C=O replaced with NH2
40
what happens in the salvage reaction of purines
Salvage system already have purine in diet | Take phosphate groups out and reattach to PRPP
41
How does purine and pyrimidine synthesis differ
Ring synthesized first in pyrimidines
42
how is glutamate, 2 ADP and carbamoylphosphate formed in synthesis of pyrimidines
combining glutamine, 2 ATP and bicarbonate
43
how is carbamoylaspartate made in synthesis of pyrimidines
Aspartate reacts with carbamoyl phosphate
44
what happens to carbamoyl asparate in synthesis of pyrimidines
carbamoyl asparate is cyclised to form the recognisable 6 membered ring of pyrimidines
45
what happens to PRPP in synthesis of pyrimidines
combined with the six membered ring
46
what happens when an amino group is added to UTP
formation of CTP
47
what is used in UTP synthesis
4 ATP (not counting PRPP formation)
48
What happens if too much CTP
CTP feeds back to step before which is causes inhibition | Carbamoyl phosphate to carbamoyl aspartate inhibited by CTP
49
What are the blocking steps in pyrimidine synthesis
Only thymidylate synthetase can synthesis dUMP to dTMP if mutated will cause problem
50
What inhibits Dihydrofolate reductase
Aminopterin | Amethopterin
51
What happens if excess of pyrimidine
Degraded by TCA cycle
52
What happens to excess purines
Degraded, released in urea of some species
53
What is the effect of allopurinol
Prevent excess uric acid | If too much will cause problems
54
What happens if uric acid is in excess
Will precipitate out
55
what is the benefit of uric acid
may contribute to longer life span and lowering incidence of cancer
56
examples of clinical applications
Pellagra, Gout, anti-Cancer drugs, Leisch Nyhan syndrome

Biochemistry (13 decks)

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