3. DNA REPLICATION
•Presented By :- Nimra Tasleem
•Reg. No. :- 2k15-PD-210
•Assigned By :- Dr. Shabana Memon
(Associate Professor Dept. of Plant Breeding & Genetics).
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8. THE LAGGING STRAND
• The lagging strand runs from 3’ to 5’.
• Before DNA replication begins there must be an RNA primer.
• The RNA primer is made by adding complimentary RNA nucleotides to the
lagging DNA strand by hydrogen bonding of the bases.
• RNA has uracil instead of thymine.
• RNA primase then bonds the RNA nucleotides together.
9. • After RNA primer is in place DNA nucleotides are added by DNA polymerase III.
• Eventually , the segment of DNA will run into another RNA primer.
• The DNA segments are called Okazaki fragments
• Once Okazaki fragments are formed DNA polymerase I replaces the RNA primer
with DNA nucleotides.
• DNA ligase links the fragments together.
