ZOOHCC - 501: Molecular Biology (Theory)



Unit 2: DNA Replication









The three models for DNA replication :-



Conservative



In the process, DNA self-replicates to create multiple copies. In
conservative replication, two DNA copies are created from the original DNA,
which serves as a template. Of these two, one is brand new DNA and the other
is the old DNA strand. This type of DNA replication is biologically
irrelevant.










Semi-Conservative



DNA replication is semi-conservative because the resulting DNA helix is
​​composed of both new and old strands in the replication process. This is
caused by complementary base pairs. That is, each nitrogenous base pairs
only with its complementary pair. These two strands are identical to the
first double helix. Each strand becomes a template for synthesizing new
strands. - DNA replication is the process of replicating DNA. - The 1958
Meselson-Stahl experiment confirmed that DNA replication is
semi-conservative. - In the semi-conservative DNA model, each DNA strand
acts as a template to generate a new complementary strand, resulting in two
DNA molecules with an old strand and a new strand. -His three different
models have been proposed for DNA replication, but the semi-conservative
model was the most popular among scientists at the time. His two other
models were called conservative and decentralized.










Dispersive replication



Dispersive replication. In the dispersal model, DNA replication produces
her two DNA molecules, which are mixtures or "hybrids" of parent and
daughter DNA. In this model, each individual strand is a patchwork of
original and new DNA.











The difference between conservative and semi conservative dna
replication

























































No
Conservative
Semiconservative Replication
1
Conservative replication is one of
the three types of DNA
replication.


Semiconservative replication is the DNA



replication mode proposed by Watson



and Crick in 1953.



2
One helix is entirely carried new DNA while the other helix
carries entirely old DNA.
Each newly formed double helix contains one new and one old
strand.


3


Not found to be biologically



significant.
Biologically significant
4
DNA doesn't split open at all.


DNA unwinds and opens for DNA replication.



5


Not clear


Each strand in the DNA double helix acts as a



template for the synthesis of a new.



complementary strand.