Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
14 Cards in this Set
- Front
- Back
|
True or False? Pyrimidines are synthesized as nucleotides.
|
False, Pyrimidines are NOT synthesized as nucleotides. Pyrimidines are completed before ribose-5-P is added. |
|
|
Carbamoyl Phosphate synthetase II (CPS II) is what type of enzyme?
|
Cystolic |
|
|
What are the precursors of the 6 atoms of the pyrimidine ring?
|
Carbamoyl-phosphate and aspartate |
|
|
What is the 1st committed step for Pyrimidine biosynthesis?
|
Synthesis of Carbamoyl phosphate from Glutamine+CO2+2ATP |
|
|
What is the 2nd step for pyrimidine synthesis?
|
Synthesis of Carbamoyl Aspartate. Carbamoyl phosphate and Aspartate are joined together by Aspartate Transcarbamoylase (ATCase) which makes Carbamoyl Aspartate. |
|
|
In the 3rd step, Dihydroorotase catalyzes Carbamoyl Aspartate to form what kind or structure?
|
A ring, dihydroorotate |
|
|
In the 4th step what causes dihydroorotate to become orotate?
|
Dihydroorotate dehydrogenase |
|
|
In the 5th step acquisition of what occurs with the aid of orotate phosphoribosyl-transferase?
|
Acquisition of ribose phosphate moiety to yield orotidylate (OMP)
|
|
|
In step 6 Orotidylate becomes what?
|
Uridylate (UMP) with OMP decarboxylase
|
|
|
In step 7 what is synthesized?
|
UTP= Uridine 5'-triphosphate |
|
|
CTP synthetase makes what out of UTP?
|
CTP= Cytidine 5'-triphosphate |
|
|
What are the advantages of multifunctional enzymes?
|
2. movement time between active sites is shortened 3. Substrates aren't diluted 4. Chemically reactive intermediates are protected 5. Intermediates don't accumulate 6. Intermediates are shielded from other enzymes |
|
|
What is the difference in pyrimidine synthesis between bacteria and mammals?
|
2. ATP is an allosteric regulator in both, but mammals are also regulated by PPRP. 3. In E. Coli, CTP and ATP compete for a common allosteric site |
|
|
How are pyrimidines degraded in humans?
|
Pyrimidines are recycled from nucleosides, free pyrimidine bases are NOT salvaged
|
