Nucleic Acid Synthesis

Nucleic Acid SynthesisThe making of what defines us

Nucleic acids Function primarily as informational molecules for the

storage and retrieval of information regarding the primary sequence of polypeptides in proteins found within a cell.

2 typesdeoxyribonucleic acids(DNA)Ribonucleic acids(RNA)

DNA cellular database Store immense amount of info regarding all possible

polypeptides a cell can make RNA mRNA, tRNA, rRNA Needed to convert DNA to polypeptide sequences

Nucleotide anatomy Nucleic acid built from nucleotides Nucleotide 3 components1. Ring shaped molecule purine/pyrimidine2. Pentose sugar 3. 1 or more phosphate groups

Nitrogenous bases Either:1. Purines (2 ring-shaped)2. Pyrimidines (1 ring-shaped) DNA 1. Adenine 2. Guanine Large purines3. Cytosine4. Thymine smaller pyrimidines

Nitrogenous bases RNA same as in DNA except Uracil

replaces Thymine.

Pentose sugars Nucleic acids pentose sugars with 5 c

atoms RNA ribose Normal sugar with 1 oxygen atom

attached to each carbon atom. DNA modified sugar Lack one oxygen atom (de-oxy) Difference is important for enzymes

which recognise DNA and RNA, allowing these 2 easily distinguished

Pentose sugar

Phosphate groups Joined together to form phosphodiester

bonds Nucleotides 1(monophosphate),

2(diphosphate), 3(triphosphate) Source of phosphate ATP or GTP Phosphate groups tendency to repel

each other high concentration of negative charge

Nucleotide phosphate Nucleoside nitrogenous base covalently

bonded to a sugar. Adenine added to sugar deoxyribose

deoxyadenosine nucleoside name Nucleotidenitro+sugar+1 t0 3 phosphate

groups Nucleotides named by combining

nucleoside name with number of phosphates

E.g Deoxyadenosine monophosphate= dAMP

Synthesis of DNA Monomers Nucleotides Strand of DNA backbone of alternating

units of phosphate and deoxyribose. Purine and pyrimidine pairs attached to

the 5C deoxyribose sugar and form base pairs with purine and pyrimidine from opposite strand.

Adenine always bind with ThymineGuanine always bind with Cytosine

DNA strand

RNA synthesis Monomers Ribonucleotides RNA single stranded Backbone consisting of alternating units

of phosphate and ribose sugar. Purine and pyrimidine bases attached to

the 5C ribose sugar.

Building blocks of nucleic acids Nucleoside combination of a base and

a sugar. 1st carbon atom of sugar linked to the

nitrogen in the: 9th position in a purine base 1st nitrogen in a pyrimidine base

Building blocks of nucleic acids Phosphoric acid forms an ester linkage

with one of the free hydroxyl groups in the pentose sugar which is a ribose or deoxyribose

1 phosphate molecule joins 2 nucleoside units by forming an ester linkage with hydroxyl group on the 3’ C atom of 1 sugar molecule and another ester linkage with the 5’ hydroxyl of the sugar of the adjacent nucleotide.

This is called the phosphodiester bond

Purine synthesis

PRPP- Phosphoribosyl-alpha-pyrophosphate PRA- Beta-5-Phosphoribosylamine GAR- Glycinamide Ribotide FGAR- Formylglycinamide Ribotide FGAM--Phosphoribosylformylglycinamidine AIR- 5-Aminoimidazole Ribotide CAIR- Carboxyaminoimidazole Ribotide SAICAR-

succinylaminoimidazolecarboxamide ribotide

AICAR- aminoimidazole carboxamide ribotide

FAICAR-Formaminoimidazole carboxamide ribotide

Pyrimidine synthesis

Orotidylate