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49 Cards in this Set

  • Front
  • Back
What are the activated precursors of DNA and RNA synthesis? x 2
1. NTP
2. dNTP
ATP is made from what?
Sugar
How do NTP's regulate protein function? x 2
1. Through phosophorylation
2. Binding and hydrolysis
A nitrogenous base + sugar = ?
Nucleoside
A nitrogenous base + sugar + phosphates = ?
Nucleotide
Name all the nitrogenous bases.
1. Adenosine
2. Cytosine
3. Guanine
4. Thymine
5. Uracil
Name all the nucleosides.
1. Adenosine
2. Cytidine
3. Guanosine
4. Uridine
Name all the deoxy nucleosides.
1. Deoxyadenosine
2. Deoxycytidine
3. Deoxyguanosine
4. Deoxythymidine
5. Deoxyuridine
Name all the nucleotides.
1. Adenylate
2. Cytidylate
3. Guanylate
4. Uridylate
Name all the deoxy nucleotides.
1. Deoxyadenylate
2. Deoxycytidylate
3. Deoxyguanylate
4. Deoxythymidylate
5. Deoxyuridylate
What are the derived components from which Purine ring is made from? 5
1. Formate
2. Glutamine
3. Glycine
4. Carbon Dioxide
5. Aspartate
What is the first step in purine synthesis?
Ribose 5 Phosphate + ATP --> PRPP.

Enzyme - PRPP synthetase
What is the first COMMITTED step in purine synthesis?
PRPP + glutamine --> Phosphoribosylamine

Enzyme - Glutamine-PRPP amidotransferase
What is the first purine made in purine biosynthesis?
Inosine
What is the base of inosinate (IMP)?
hypoxanthine
IMP with the addition of ATP becomes what?
GMP
IMP with the addition of GTP becomes what?
AMP
What is the precursor for AMP and GMP?
IMP
If ATP is higher than GTP, more IMP will be converted to what?
GMP
If GTP is higher than ATP, more IMP will be converted to what?
AMP
What are the inhibitors of PRPP synthetase?
IMP
AMP
GMP
What are the inhibitors of Glutamine-PRPP amidotransferase?
IMP
AMP
GMP
What are the inhibitors of adenylosuccinate synthetase?
AMP
What are the inhibitors of IMP dehydrogenase?
GMP
The pyrimidine ring is made from what components?
Carbamoyl phosphate and Aspartate
What is the first step of pyrimidine synthesis?
Glutamine + 2 ATP + HCO3- --> Carbamoyl Phosphate

Enzyme - Carbamoyl Synthetase II
Carbamoyl synthetase II is found where?
Cytosol
What is the first COMMITTED step in pyrimidine synthesis?
Carbamoyl Phosphate + Aspartate --> N-Carbamoylaspartate

Enzyme - Aspartate transcarbamoylase
What does the enzyme dihydroorotase do?
Ring closure of pyrimidine
What is CAD?
Trimer enzyme containing Carbamoyl synthetase, Aspartate Transcarbamoylase, and Dihydroorotate.
What is dihydrooroate?
Closed off ring of pyrimidine synthesis
What part of pyrimidine synthesis occurs in the mitochondria?
Dihydroorotate diffuses into mitochondria where it is oxidized by dihydroorotate dehydrogenase to become orotate.
What happens first to orotate in the cytosol?
In the presnece of PRPP, becomes subject to orotate-phosphoribosyl transferase, to become orotidylate.
What happens to orotidylate?
Becomes subject to orotidylate decarboxylase to become UMP (Uridylate)
What is unique about the enzymes orotate phosphoribosyl transferase and orotidylate decarboxylase?
On the same enzyme
What is the disorder associated with the defect in Orotate Phosphoribosyl Transferase AND Orotidyl Decarboxylase?
Oroticaciduria type I
What is the disorder associated with the defect in Orotidylate Decarboxylase?
Oroticaciduria type II
What are the markers for patients with oroticaciduria?
Anemia and high levels of orotate.
Uridylate (UMP) becomes UTP how?
Kinases
UTP becomes CTP (Cytidine) how?
Addition of glutamine under the subjection of cytidylate synthetase.
In animals, what are the activators of Carbamoyl Synthetase II?
PRPP and ATP
In animals, what are the inhibitors of Carbamoyl Synthetase II?
UTP and CTP
In animals, what is the enzyme that needs to be regulated in pyrimidine synthesis?
Carbamoyl Synthetase II
In bacteria, what is the enzyme that needs to be regulated in pyrimidine synthesis?
Aspartate Transcarbamoylase
What is the reasoning behind the rare incidence where the first committed step is not the regulated step?
Because carbamoyl phosphate is also made in the urea cycle.
Why do some Urea cycle disorders increase orotate levels.
B/c carbamoyl phosphate is common to both urea cycle and pyrimidine synthesis. A urea cycle disorder will lead to carbamoyl phosphate diffusing out of the mitochondria, leading to increased pyrimidine synthesis.
What pathways are involved in carbamoyl synthetase?
Carbamoyl synthetase I - Urea cycle

Carbamoyl synthetase II - Pyrimidine synthesis
Where would you find the carbomoyl synthetases?
Carbamoyl Synthetase I - in mitochondria

Carbamoyl Synthetase II - in cytosol
What do the Carbamoyl Synthetases use?
Carbamoyl Synthetase I - uses NH4 + HCO3-

Carbamoyl Synthetase II - uses glutamine and HCO3-