DNA replication

Transfer of genetic information

a) inheritance (via copied DNA) replication

b) expression (via mRNA) transcription

DNA replication

• DNA, the genetic material of the cell, needs to be replicated every time the cell divides
• during mitosis and meiosis, cells divide to form two daughter cells and the DNA needs to be replicated
• DNA replication is the process of copying a parental DNA molecule to form two daughter DNA molecules

DNA replication is semi-conservative

• double stranded DNA is unwound by helicase
• each strand of the original double stranded DNA serves as a template for a new strand
• an exact copy of the parent molecule is made
• the new strands are called daughters strands
• a parental strand is present in both daughter strands

What is need for DNA replication

• the double helix needs to be unwound and separated to provide a template for copying
• the polymerase needs a primer to start copying the DNA
• dNTPS are needed to elongate the new strand
• to replicate double stranded DNA by a DNA polymerase, many proteins and enzymes are required which act in a coordinated and cooperative manner
• polymerase requires complementary nucleotides and primers

Components needed for replicating DNA

• DNA helicase
• SSBs
• topoisomerases
• primase
• DNA polymerase
• sliding DNA clamps
• RNAse H
• DNA ligase

Step one: separation of the two parental strands at the origin of replication

• in order for the two parental strands to be replicated they must first be separated (or melt) in…