Lecture 49 Flashcards Preview

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Flashcards in Lecture 49 Deck (19)
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1
Q

_____ is the precursor for Cytosine, Thymine, and Uracil.

A

OROTIC ACID

2
Q

_____ phosphate synthetase II is specific to Pyrimidine biosynth and is located in the _____, whereas _____ phosphate synthetase I is specific to the _____ cycle and is located in the ____ _____.

A

CARBAMOYL phosphate synthetase II is specific to Pyrimidine synthesis and is located in the CYTOSOL, whereas CARBAMOYL phosphate synthetase I is specific to the UREA cycle and is located in the MITOCHONDRIAL MATRIX.

3
Q

_____ is a carbon source and _____ is an amino source for Carbamoyl phosphate for pyrimidine synthesis. It is also an amino source in ____ synthesis.

A

HCO3 is a carbon source and GLUTAMINE is an amino source for Carbamoyl phosphate for pyrimidine synthesis. It is also an amino source for PURINE synthesis.

4
Q

Carbamoyl Phosphate synthetase is inhibited by _____ and activated by _____ and _____.

A

It is inhibited by UTP, and activated by ATP and PRPP.

5
Q

Pyrimidine synthesis differs from Purine synthesis in that Pyrimidine synth begins with _____ formation followed by link to _____. This is opposite in Purine synth.

A

Pyrimidine synthesis begins with RING formation followed by link to RIBOSE.

6
Q

CAD is a single polypeptide with 3 domains, each with a different catalytic activity, including ______ ______ ______ (C), ______ ______(A), and ______ (D)

A

Including Carbamoyl Phosphate Synthetase, Aspartate Transcarbamylase, and Dihydroorotase.

7
Q

The second enzyme complex involved in pyrimidine synth is _____ synthase, which is composed of orotate phosphoribosyl transferase that adds _____ to Orotate forming OMP and then OMP decarboxylase forming ____ from OMP.

A

The second enzyme complex is UMP-synthase, which is composed of orotate phosphoribosyl transferase that adds PRPP to Orotate forming OMP and then OMP decarboxylase forming UMP from OMP.

8
Q

Low UMP synthase activity (in either one of the 2 enzyme components) leads to _____ aciduria, showing symptoms such as _____ anemia and abnormal growth. It can be treated with a _____-rich diet.

A

It leads to OROTIC aciduria, showing symptoms such as MEGALOBLASTIC anemia and abnormal growth. It can be treated with a URIDINE-rich diet.

9
Q

____ is the AA that is unique to purine synthesis; both Glutamine and Apartate are shared.

A

GLYCINE is unique.

10
Q

____ synthetase forms Cytosine from Uracil (UTP) and requires _____ and Glutamine.

A

CTP synthase forms Cytosine from Uracil and requires ATP and Glutamine.

11
Q

Pyrimidine degradation products are ____, so there are no equivalent disorders as in Purine degradation, which can lead to Gout.

A

They are SOLUBLE.

12
Q

______ ______ and ______ ______ are the 2 enzymes required to convert RNA to DNA.

A

THYMIDYLATE SYNTHETASE and RIBONUCLEOTIDE REDUCTASE

13
Q

Ribonucleotide Reductase reduces the C at the _____ position, forming a C-H bond instead of the C-OH that was there originally.

A

It reduces the C at the 2’ position.

14
Q

_____ is a general inhibitor of Ribonucleotide reductase and _____ is a general activator.

A

dATP is a general inhibitor, and ATP is a general activator.

15
Q

Ribonucleotide reductase only recognizes the _____phosphate forms of the Nucleotides.

A

It only recognizes the DIphosphate forms.

16
Q

Before being converted to dTTP, dUDP is first converted to _____, which then gains a Carbon unit from ____ to form _____, which is then phosphorylated to dTTP.

A

dUTP is first converted to dUMP, which then gains a Carbon unit from THF to form dTMP, which is then phosphorylated to form dTTP.

17
Q

______ synthase coverts dUMP to dTMP using THF, (which is oxidized to form DHF) for the one Carbon unit. THF regains its electrons from _____ via the enzyme DHF reductase and regains its Carbon from _____ transhydroxymethylase.

A

THYMIDYLATE synthase converts dUMP to dTMP using THF. THF regains its electrons from NADPH via the enzyme DHF reductase and regains its Carbon unit from SERINE transhydroxymethylase.

18
Q

5-FU and Methotrexate are used as chemotherapies by inhibiting ______ synthase.

A

They inhibit THYMIDYLATE synthase.

19
Q

Chemotheraputic index = maximum tolerable dose / minimum dose that will cure the disease

A

The higher the theraputic index, the better.