Mechanism of DNA Replication (Advanced)

Knowing the structure of DNA, scientists speculated and then proved that DNA is the template for copying the genetic code. See how information in DNA is copied to make new DNA molecules.
Originally created for DNA Interactive ( http://www.dnai.org ).
TRANSCRIPT: During DNA replication, both strands of the double helix act as templates for the formation of new DNA molecules. Copying occurs at a localized region called the replication fork, which is a Y shaped structure where new DNA strands are synthesised by a multi-enzyme complex. Here the DNA to be copied enters the complex from the left. One new strand is leaving at the top of frame and the other new strand is leaving at bottom. The first step in DNA replication is the separation of the two strands by an enzyme called helicase. This spins the incoming DNA to unravel it: at ten thousand RPM in the case of bacterial systems. The separated strands are called three prime and five prime, distinguished by the direction in which their component nucleotides join up. . The 3' DNA strand, also known as the leading strand, is diverted to a DNA polymerase and is used as a continuous template for the synthesis of the first daughter DNA helix. The other half of the DNA double helix, known as the lagging strand, has the opposite 3' to 5' orientation and consequently requires a more complicated copying mechanism. As it emerges from the helicase, the lagging strand is organised into sections called Okazaki fragments. These are then presented to a second DNA polymerase enzyme in the preferred 5' to 3' orientation. These sections are then effectively synthesised backwards. When the copying is complete, the finished section is released and the next loop is drawn back for replication. Intricate as this mechanism appears, numerous components have been deliberately left out to avoid complete confusion. The exposed strands of single DNA are covered by protective binding proteins. And in some systems, multiple Okazaki fragments may be present. The molecular reality is very different from the iconic image of the double helix neatly separating into two DNA copies as so often depicted.

Category:

Education

Tags:

• dna replication animation
• dna double helix
• dna polymerase
• dna molecules
• computer animation
• location code
• jet engine
• assembly line
• using computer
• narration
• end result
• strands
• strand
• cells

[TheMordyS]

SLOW DOWN!!

[saguhh00]

Why does this video have dislikes? Are there people who don't believe in DNA?

[saguhh00]

@nez191 That's not a reason for disliking the video.

[nez191]

@saguhh00 b/c they need more details

[alelp]

@RodAGTotoro Wow, thanks for the information man, keep it up : D

[boblee666]

@ackilla86 NO THE GREATEST MATHEMATICIAN.

[clairebehun]

love the video man

[ackilla86]

our Creators are THE greatest scientists ever!

[qrais]

@RodAGTotoro thank you very much for your answer. Thank you.

[RodAGTotoro]

@vldk29 I guess your last question was asked in my first reply. The light green structure being the primase and the dark green being the clamps. The primase adds a new primer and then dissociates. The clamp closes around the the new template primer, the core polymerase gets the clamp with the DNA associated to it and DNA synthesis keeps on going and going and going on forever. Well... at least until the end of the chromosome is reached.

[RodAGTotoro]

@qrais It depends on which species and which polymerase are you talking about. In E. coli there are at least 5 polymerases, the one depicted here is the DNA pol 3, which is made up of at least 10 subunits.

E. coli DNA pol 1 is made of 1 subunit and E coli DNA pol II is made of 7 different subunits.