MCM - Nucleotide Metabolism Flashcards Preview

Biochemistry > MCM - Nucleotide Metabolism > Flashcards

Flashcards in MCM - Nucleotide Metabolism Deck (47):
1

Nucleosides vs. Nucleotides

Nucleosides have a Base and a Sugar

Nucleotides have: Base, Sugar, and Phosphate

2

How is Adenine bonded with the Ribose Sugar

Via a Glycosidic Bond

3

How many Carbons does a Purine have in its ring

9

4

How many carbons does a Pyrmadine have in its carbon ring

6

5

Which bases are in DNA

Adenine
Guanine
Cytosine
Thymine

6

Which bases appear in RNA

Guanosine
Uracil
Adenine
Cytosine

7

What are some other roles of Nucleosides and Nucleotides

ATP & GTP

Cosubstrates

Components of Co-Factors
CoA
FAD
FMN
UDP-Glc
NAD+
NADP+

Regulatory Role
cAMP
gAMP
m7GTP

Important Biomolecules;
Vitamin B12

8

Are the carbon sources for Purine and Pyrmadine Ring formation the same

No

9

Purine Synthesis Basic Steps

Sugar Molecule Synthesis

AND THEN

Ring Formation

10

Pyrmadine Synthesis Basic Steps

Ring Formation

AND THEN

Sugar Formation

11

How many phases of De Novo Synthesis does it take to make a Purine

4 stages

12

What are the 4 stages of the De Novo Synthesis for Purine Formation

  1. Ribose-5-P Activation; phosphorylation of Ribose-5-P to Phospho-Ribosyl-Pyro-Phosphate (PRPP)
  2. Conversion of PRPP to Phosphoribosylamine (PRA); the rate limiting step of the De Novo Synthesis of Purines
  3. Conversion of PRA to an Inosine Monophosphate (IMP) (Ring)
  4. Conversion of IMP to Adenosine or Guanosine

13

What does Methotrexate inhibit in the De Novo Synthesis

The synthesis of the IMP ring for Purine Synthesis

14

What is IMP converted to

Guanosine
or
Adenosine;

Depending on GMP/AMP Levels

15

Sulfa drugs effect on Folate

Inhibit the Bacterial DHPS and DHFR; so the bacterial, viral, or fungal cells cannot make folate from PABA

16

What is the feedback inhibition on the De Novo Synthesis of Purines

Accumulation of PRPP
Accumulation of PRA
Accumulation of GMP/AMP

17

What is the rate limiting step in the synthesis of Pyrmidine Ring

Carbamoyl Phosphate + Aspartate --->
Carbamoylaspartate

Enzyme: Aspartate Transcarbamoylase

18

How many Steps is the Synthesis of a Pyrmidine

3 Steps

19

What are the Steps of synthesizing a Pyrmidine Ring

  1.  Fabrication of orotate ring
  2. Attachment of PRPP to form UMP
  3. Convert UMP to uridine, cytosine, and thymidine

20

What are the two major regulatory steps in Pyrmidine Synthesis

Carbamoyl Phosphate Synthetase

And

Aspartate Transcarbamoylase

21

What inhibit Carbamoyl Phosphate Synthetase

UMP
And
Purines

22

What Stimulates Carbamoyl Phosphate Synthetase

PRPP

23

What does CTP Inhibit via Feedback Inhibition

Aspartate Transcarbamoylase

 

24

What is the cancer drug for Pyrmidine Synthesis

Adrucil
(5-Fluorouracil)

Mechanism not clear; likely inhibits Thymidylate Synthase

25

What are the two defective enzymes in Oroctic Aciduria

Orotate phosphoribosyl transferase

and

Oritidine Carboxylase

26

How does Acyclovir work

Acts as a Nucleoside; which binds a phosphate

Leads to DNA Polymerase being blocked by a false nucleotide; the name of the kinase that is blocked is Thymidine Kinase, only in virally infected cells

 

27

What is Acyclovir generally used for

Herpes Lesions
and
Chicken Pox

28

Where does Pyrmidine Synthesis Occur

In the Cytosol
And
The Mitochondria

29

What do Ribonucleases do

Convert RNA to short oligomers

30

What do Deoxyribonucleases do

Convert DNA to short oligomers

31

What do Phosphodiesterases do

Convert short oligomers to NMP's or dNMP's

32

What does a Nucelotidase do

Converts dNMP/NMP into nucelosides and deoxynucelosides

33

What do Nucleosidases do

Remove Ribose group and converts them into Pyrmidines or Purines

34

What is Uric Acid a product of

Purine Nucleotide Catabolism

35

What does a build up of Adenosine Deaminase do

Causes hemolytic anemia

36

What does underproduction of Adenosine Deaminase do

Associated with the second most common form of sever combined immunodeficiency (SCID)

37

What is Gout caused by 

A build up of Uric Acid from eating to many high protein foods and drinking too much wine

38

How are Uric Acid Crystal Formed

Urate binds with sodium to make Monosodium Urate; which is not water soluble

This precipitates out of solution are forms Uric Acid Crystals

39

What does Pyrmidine Nucleotide Catabolism Produce

Malonyl-CoA; Can go into Fatty Acid Synthesis
or
Methylmalonyl-CoA and Succinyl-CoA; Can go into TCA Cycle

40

What is used in the Catabolism of Pyrmidine Nucleotides to determine DNA Turnover

ß-Aminoisobutyrate

41

What is the Pyrmidine Nucleotide Salvage Pathway

Takes Pyrmidines to their respective -TP molecule

42

What is the Purine Salvage Pathway

Takes a Purine into their respective -MP 

43

Lesch-Nyhan Syndrome Cause

Defect in the HGPRT enzyme in the Purine Salvage Pathway

44

What does the defect in HGPRT Produce in Lesch-Nyhan Syndrome

Overproduction of Uric Acid

45

How do patients present with Lesch-Nyhan Syndrome

Hyperuricemia and Hyperuricosuria

46

What are the symptoms of Hyperuricemia and Hyperuricsuria

Urate Kidney Stones, Poor Muscle Control, Mental Retardation, and tendency FOR SELF MUTILATION

47