DNA replication models I semiconservative , conservative and dispersive model I

The model that Watson and Crick proposed in 1953 to describe the molecular structure of DNA was a landmark discovery. But at the time, many scientists weren't convinced that the model was right. Along with their structural model of DNA, Watson and Crick also proposed a model to describe how DNA is copied inside a cell. Many scientists thought their model of DNA production didn't make sense, and it led some people to doubt whether they were even right about the double helix. Let's learn more about the science behind DNA discoveries to find out how this problem was solved.

Scientists had known for a very long time that organisms make copies of their DNA. Making extra copies of the instructions in DNA allows an organism to grow and reproduce. The scientific word for 'copy' is 'replication.' So when we talk about DNA making copies of itself, we call it DNA replication.

Three Different Models for DNA Replication
Watson and Crick had proposed that in order to copy itself, DNA would have to open down the center, sort of like a zipper coming apart, so that a new DNA strand could be built on top of the exposed strands. Following the rules of complimentary base pairing, adenine would pair with thymine, and cytosine would pair with guanine. This idea was called a template model, since one DNA strand serves as the template for a new one.

Watson and Crick figured that this model would result in two new double strands of DNA, each one with one strand of parent (or template) DNA and one strand of daughter (or newly-synthesized) DNA. They called this the semi-conservative model, because half of the parent DNA was conserved in each new DNA molecule.

Scientists looked at the double helix of DNA and wondered how in the world it could possibly open itself up without getting tangled or torn apart. So they thought up some other ideas about how DNA replication works. One hypothesis, called the dispersive model, suggested that DNA only copied itself for short chunks at a time, producing new strands that alternated parent and daughter DNA. Another idea, called the conservative model, argued that DNA didn't split open at all, but somehow kept the parent strands intact while creating an entirely new and separate copy.

Nobody knew for sure how DNA replication really worked until two scientists named Matthew Meselson and Franklin Stahl devised an ingenious experiment in 1958. They realized that they could test all three models at once by keeping track of what happens to one parental DNA strand as it generates a series of copies.

[neelyclendenin]

So hard to find anything quick and simple one the internet. Especially on things like this. I appreciate you making it available in such an easy way to comprehend!

[charles-philippegilbert]

Using only the red and black lines really simplified it, thank you man I understand this now.

[muskangarana]

Sir, you didn't explained f2 generation

[akhilageorge]

In conservative mode, how the new copy of DNA gets formed?

[safaebenaata]

from morocco thank u a lot for your explication

[riffatrehmat]

Thanks ap ki video achii or helpful ha but ap thoda peachy khary hua Karin hum ny screenshot lyna hota ha plzzz

[ranshanikorawa]

I understood everything ! Thank you so so much

[abdullahikram]

Very well explained, thank you so much!

[basitahmad]

Bhai urdu main class lena chahian
Ap k videos ya to india main ya pakistan main log dekan gain .
Is main aise students bhi hoge jo jisko english samaj nahi ati hogi..

[alishashashasha]

Tysm sir, it was easy to understand and well explained!!

[sanketsingh]

awesome video..helped just before exams

[mahinmahi]

Sir what is the advantage of semi coservative replication?

[adreeskambo]

Sir can you explain in Urdu or Hindi ?

[sujuoudmohammad]

Thank you alot really so benefit you are amazing... keep goin

[aadilazad]

Change yr marker color before teaching replication of DNA, the red & blue is not clear combination in dna Duplex, and not clearly seen