Understanding DNA Replication: Semi-Conservative Model and Process, Lecture notes of Genetics

Download Understanding DNA Replication: Semi-Conservative Model and Process and more Lecture notes Genetics in PDF only on Docsity!

DNA REPLICATION

Semi Conservative

Model

DNA REPLICATION

Semi Conservative

Model

DNA (^) RNA protein replication transcription translation

Central dogma

DNA (^) RNA protein reverse transcription

DNA Replication DNA Replication

 (^) Putting the DNA backbone together ◦ refer to the 3 and 5 endsof the DNA PO 4 O base 1  2  4  C 3  O 5 CH 2 O base

• O 1  P (^) O O 5 CH 2 4  2  3  2  OH 4  C 3  O By- Siddharth Isamaliya 7

Template: Substrate: Primer: double stranded DNA dNTP short RNA fragment with a free 3

´-OH end

DNA-dependent DNA polymerase (DDDP), other enzymes, protein factor

DNA replication system

double stranded DNA dNTP short RNA fragment with a free 3

´-OH end

DNA-dependent DNA polymerase (DDDP), other enzymes, protein factor Enzyme:

Semi-Conservative Replication

Semiconservative replication

Half of the parental DNA molecule is conserved in each new double helix, paired with a newly synthesized complementary strand. This is called semiconservative replication Half of the parental DNA molecule is conserved in each new double helix, paired with a newly synthesized complementary strand. This is called semiconservative replication

Bidirectional Replication

• Replication starts from unwinding the dsDNA at a particular point (called origin), followed by the synthesis on each strand.
• The parental dsDNA and two newly formed dsDNA form a Y-shape structure called replication fork.
• Replication starts from unwinding the dsDNA at a particular point (called origin), followed by the synthesis on each strand.
• The parental dsDNA and two newly formed dsDNA form a Y-shape structure called replication fork.

3 ' 5' 5' 3 ' 5' 3 '

Replication fork

3 ' 5' 5 ' 3' 5' 3 '

direction of

replication

Bidirectional replication

Replication of prokaryotes

The replication process starts from the origin, and proceeds in two opposite directions. It is named  replication. The replication process starts from the origin, and proceeds in two opposite directions. It is named  replication.

Semi-continuous Replication

The daughter strands on two template strands are synthesized differently since the replication process obeys the principle that DNA is synthesized from the 5 ´ end to the 3 ´end. The daughter strands on two template strands are synthesized differently since the replication process obeys the principle that DNA is synthesized from the 5 ´ end to the 3 ´end.

On the template having the 3 ´- end, the daughter strand is synthesized continuously in the 5 ’-3’ direction. This strand is referred to as the leading strand.

Leading strand

5' 3' 3' 5' 5' direction of unwinding 3' On the template having the 3 ´- end, the daughter strand is synthesized continuously in the 5 ’-3’ direction. This strand is referred to as the leading strand.