DNA replication :
The process by which DNA makes a copy of itself during cell division is called DNA replication.
1) ‘unzip’ the double helix structure of the DNA molecule is the first step in DNA replication.
2) Helicase enzyme breaks the hydrogen bonds holding the complementary bases of DNA together (C with G, A with T).
3) The two single strands of DNA separates to creates a ‘Y’ shape called a replication ‘fork’. This two separated strands will act as templates for making the new strands of DNA.
4) 1 strands is oriented in the 3’ to 5’ direction, this is called leading strand. But the other strand is oriented in the 5’ to 3’ direction ,this is known as lagging strand. Due to their different orientations, the two strands are replicated separately.
1) ‘unzip’ the double helix structure of the DNA molecule is the first step in DNA replication.
2) Helicase enzyme breaks the hydrogen bonds holding the complementary bases of DNA together (C with G, A with T).
3) The two single strands of DNA separates to creates a ‘Y’ shape called a replication ‘fork’. This two separated strands will act as templates for making the new strands of DNA.
4) 1 strands is oriented in the 3’ to 5’ direction, this is called leading strand. But the other strand is oriented in the 5’ to 3’ direction ,this is known as lagging strand. Due to their different orientations, the two strands are replicated separately.
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| DNA replication |
Replication of leading and lagging strands of DNA:
Leading Strand:
A primer (a short piece of RNA ) comes along and binds to the end of the leading strand. This primer is the starting point for DNA synthesis.
Add new complementary nucleotide bases (A, T, G and C) to the strand of DNA in the 5’ to 3’ direction.
Lagging strand:
1. It is also a replicated strand of DNA, but it is formed in short segments called Okazaki fragments. Its growth is discontinuous.
1. It is also a replicated strand of DNA, but it is formed in short segments called Okazaki fragments. Its growth is discontinuous.
2. For joining Okazaki fragments DNA ligase enzyme is required .
"DNA replication " "Replication of leading and lagging strands of DNA"