Nucleotide synthesis

Question 1

what are 2 pathways for the synthesis of nucleotides

Answer 1

de novo synthesis and salvage pathway

Question 2

what is de novo synthesis

Answer 2

(literally means anew or from the beginning): Biochemical
pathway where nucleotides are synthesised from new simple precursor molecules

Question 3

what is salvage pathway

Answer 3

Used to recover purine or pyrimidine compounds formed during the degradation of RNA/DNA that would be otherwise lost

Question 4

what key metabolite plays a role in de novo and salvage

Answer 4

PRPP: Phosphoribosyl pyrophosphate

Question 5

what is the equation for PRPP

Answer 5

ATP + Ribose-5-phosphate ↔ PRPP + AMP

Question 6

what occurs in the De novo biosynthesis of purines

Answer 6

1. Ribose-5-phosphate is the starting material
2. Reacts with ATP to form phosphoribosyl pyrophosphate (PRPP)
3. PRPP is the first intermediate in a 10-step pathway in production of IMP

Question 7

what occurs in De novo biosynthesis of purines: GMP and AMP

Answer 7

there is a GMP and an AMP pathway and they are converted to triphosphates by 2 successive phosphorylations. Conversion firstly to diphosphates involves specific ATP-dependent kinases. ATP is phosphate donor to convert GDP (nucleoside diphosphates) to triphosphates - nucleoside diphosphate kinase (NDP kinase)

Question 8

what is the salvage pathway

Answer 8

salvage pathways are the recycling of products of nucleic acid breakdown/ dietary supply
* Requires less energy than de novo pathway
* Starts with free bases