Flashcards in Lecture 21 - Nucleotide Metabolism Deck (23)
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1
The committed step of purine synthesis is _____.
PRPP to phsophoribosylamine (activated by the addition of C1 amine group)
2
Closes the nitrogenous base in purine synthesis
tetrahydrofolate (specifically, N5-formyl THF)
3
Reduces NDPs to dNDPs
ribonuclease reductase
4
Inosinate is the intermediate in ___ and ___ production.
dATP and dGTP production
5
Between __ and ___, the N-base rings are built in purine synthesis.
phosphoribosylamine; inosinate
6
Closes the purine ring structure
N10-formyl THF
7
Feedback inhibition of purine synthesis:
PRPP and PR-amine is inhibited by _____
IMP/GMP/AMP
8
Step 1 of de novo purine synthesis occurs when ______ catabolizes ribose-5-phosphate to phosphoribosyl pyrophosphate
PRPP synthase
9
Why is purine salvage an important biochemical process?
Pyrimidine triphosphates are important energy carriers (ATP; GTP), so they are salvaged to "run" other processes.
10
Purine salvage involves the loss of ____ from ribose to attach the nitrogenous base.
C1 Pi (the inorganic phosphate from Carbon 1)
11
Catalyst for AMP salvage
adenine phosphoribosyl-transferase (APRT)
12
Catalyst for guanine salvage
Hypoxanthine-guanine phosphoribosyl-transferas (HGPRT)
13
Pyrimidines are salvaged by ______.
Phorphorylases
14
Phosphoribosyl-5-pyrophosphate (PRPP) is important as it is critical in the production of _______ ______.
A. ATP molecules
B. GTP molecules
C. FAD molecules
D. Purine nucleotides
D. purine nucleotides (A & G)
15
GTP and ATP production use what for energy?
ATP for GTP production
GTP for ATP production
16
IMP production is inhibited by _____.
AMP/GMP
17
GMP production is stimulated by _____.
ATP (ATP needs more GMP to bind to)
18
AMP production is stimulated by _____.
GMP (GMP needs more ATP to bind to)
19
What is produced first in pyrimidine synthesis?
Carbamoyl phosphate (made by carbamoyl phosphate synthase II)
20
Carbamoyl phosphate is transformed into carbamoyl-aspartate by _________.
ATCase (Aspartate-trascarbamylase)
21
Dihydroorotate is changed to orotate in the _____.
mitochondria
22
Orotate and ____ join to begin the final pyrimidine structure.
PRPP
23
