5 End And 3 End

DNA-polymerase can merely work from the five'-cease to the 3'-end.

I remember in society to sympathize, but think of the structure of a nucleotide.

dna

1) A nucleotide has a free 5' phosphate end and a free 3' OH stop.

2) A strand in 5' to three' direction indicates a costless 5' phosphate at ane end and a free 3' OH at the other finish.

3) Deoxyribonucleic acid polymerase requires a free 3' OH end to add the incoming nucleotide. Nucleotides monomers are added to the 3' OH end of the growing strand one by one by Deoxyribonucleic acid polymerase. That is the bonding is between the 3' OH end of the first nucleotide and 5' P end of the incoming nucleotide (and is the phosphodiester bond) . There fore new polynucleotide concatenation is always synthesised in 5'-iii' direction.

iv) Dna pol III involved in replication cannot add the first nucleotide to beginning the synthesise of daughter DNA strand.

How DNA polymerisation is initiated?

DNA polymerase cannot initiate a synthesis but information technology requires a primer called primase, an RNA polymerase.

DNA replication leading and lagging strand

It synthesise a primer or a short sequence of nearly 10 RNA nucleotides complementary to parental Dna strand. Information technology is called primer RNA. DNA pol III recognises the primer that provide a gratuitous 3'OH finish and adds Dna nucleotide to construct new DNA strand. Later RNA primer is replaced by Dna nucleotides by DNA pol I.