 - Salvage pathway (uses recycled bases)
- Attach these bases to activated ribose platform (PRPP)
- 5-phosphoribosyl-1-pyrophosphate (PRPP)
- - Makes a nucleotide
> More detailed information:
> 5-phosphoribosyl 1-pyrophosphate + guanine
> Yields: Guanosine monophosphate + pyrophosphate
> Enzyme catalyzed, driven forward by PPi -> 2 Pi


Salvage Pathway (uses recycled bases)

- Add PRPP + amino acids + ATP + CO2 + more
Makes a nucleotide

- 2 different strategies
> Pyrimidine rings are formed first and then are attached to activated ribose (PRPP)
Make UTP and then CTP
>Ribonucleotides that can be used to make RNA
>Then UTP can make TMP and CTP can make dCTP
>Deoxyribonucleotides that can be used to make DNA
 
> Purine rings are formed piece by piece right on the ribose-based structure (PRPP)
> They first make the intermediate IMP
> Then go to ATP and GTP
> Ribonucleotides that can be made into RNA
> ATP can make dATP and GTP can make dGTP
Deoxyribonucleotides that can be used to make DNA


De Novo Pathways (making bases)

- Salvage Pathway (uses recycled bases)
- De Novo Pathway (making bases)

Michigan State University

Nucleotide function

1. Precursors for nucleic acid synthesis: DNA, RNA

2. ATP is the prime energy source for biologic processes, GTP is sometimes used
Molecular motors, active transport of solutes across membranes

3. Nucleotides can activate biomolecules for synthetic reactions: 
 - UTP activating glucose, CTP activating alcohol head groups
 - ATP activation in several reactions

4. Nucleotides and derivatives are important parts of many second messenger systems (Cyclic AMP, cyclic GMP )

5. ATP is a source of phosphate for kinase reactions

Seen in regulation
Glycogen synthesis and degradation
Glycolysis


Nucleotides

THE STRUCTURE OF NUCLEOSIDES
- Ribonucleoside - ribose sugar + base
- Deoxyribonucleoside - deoxyribose sugar + base
 >Adenosine is an example of a nucleoside
 >Deoxyadenosine is a deoxynucleoside

1. Sugar - can have ribose or deoxyribose
2. Nitrogenous bases:
>Purines: Adenine, Guanine
> Pyrimidines: Cytosine, uracil, thymine

Nucleotides are nucleotides plus 1, 2, or 3 phosphates


Nucleosides

Nucleotide Synthesis

- The breakdown of nucleotides relies on three major classes of enzymes
- Nucleotidases: Convert nucleotides to nucleosides by removing a phosphate group
- Nucleoside phosphorylases: Nucleoside to a free base and ribose 1-P
- Phosphoribomutase (isomerization): Ribose 1-P to ribose 5-P
> Ribose 5-P can be recycled to make more nucleotides


Nucleotide Catabolism

Polymerase chain reaction (PCR) was discovered in 1985. It is technique usedin laboratories that allows for the synthesis of a lot of a specific fragment of DNA 

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Related

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