Question

for the formation of the leading strand and the lagging strand RNA primer formed by RNA primase is used rite .?
the only difference is that :
1)lagging strand is of continuos synthesis by lagging strand of discontinuous synthesis
2)leading strand has a polarity of 3^'-5^' so the new strand base paired in 5^'-3^' direction
but the lagging strand has polarity of 5^'-3^'direction how does the fragments form ?

Answer 1

Dear student.

The main enzyme involved in DNA replication is the DNA-dependent DNA polymerase. This enzyme catalyses the polymerisation of deoxynucleotides along the 5′ → 3′ direction, and hence, replication is continuous along the 3′ → 5′ strand (leading strand) and discontinuous along the template, i.e., the 5′ → 3′ direction (lagging strand).

Okazaki fragments are short DNA segments on the lagging strand, formed in the 5’ – 3’ direction, starting from RNA primers. A separate RNA primer is needed for the synthesis of each Okazaki fragment. These discontinuously synthesized fragments are later joined by the enzyme DNA ligase.

The polarity of template strand is always 3' to 5' and while that of coding stand is 5' to 3'.

Regards.