Nucleotides Pyr Flashcards Preview

MCB 2 Block 3 > Nucleotides Pyr > Flashcards

Flashcards in Nucleotides Pyr Deck (13):
1

Pyrimidine Ingredients

Gln, Asp, CO2, ATP, PRPP, FAD

2

Pyrimidine Synth step 1

Make carbomyl phosphate
Gln, CO2, ATP used
Enz = CPS 2 (same as CPS 1 but not in mito)
Rqrs PRPP inhib by UTP

3

Pyrimidine Synth step 2-4

Make orotic acid
From addition of Asp to Carbomyl phosphate, makes body of pyr

4

Pyrimidine Synth step 5-6

Finish body
Orotate binds PRPP to OMP to UMP
enz = UMP synthase

5

Pyrimidine Synth step 7

UMP to UDP
rqrs ATP, UDP to UTP or dUDP therefore number of P added determines UDP outcome

6

Pyrimidine Synth step 8a

UDP to CTP/dCTP
UDP to UTP to CTP (rqrs Gln)
CTP minus P (ribonucleotide reductase) to dCTP

7

Pyrimidine Synth step 8b

UDP to dUDP
enz = ribonucleotide reductase which reduces ribose sugar and is used for all DNA
act by ribonucleotides and inhib by deoxyribonucleotides (enough DNA)
Rqrs Thioredoxin and NADPH; irreversible

8

Pyrimidine Synth step 8c

dTDP
UDP to dUDP (ribonuc reductase) to dUTP (add P) to dUMP (minus PP) to dTMP (add CH3, via thymidylate synthase, rqrs THF-Me)

9

Pyrimidine Degrade

Degraded to soluble molecules which are converted to acetyl CoA, Succinyl CoA
No salvage pathway

10

Orotic Aciduria

Mut in subunits of UMP synthase; Orotate phosphoribosyl transferase or OMP decarboxylase
leads to poor growth, megoblastic anemia, orotic aciduria
Treatment is admin of uridine to improve anemia and decrease excretion of orotic acid as it inhibs CPS2

11

Xeroderma Pigmentosa

AR
Pyr dimerization due to UV dmg, no nucleotide excision repair

12

Methylated Cytosines

When cytosines are methylated by SAM, they can spont deaminate to Thymine
Screws up DNA sequence

13

5-Fluorouracil

Prevents dUMP methylation therefore inhib thymine buildup