3rd hour
-
Upload
hidayatul-illah -
Category
Technology
-
view
1.857 -
download
0
Transcript of 3rd hour
![Page 1: 3rd hour](https://reader033.fdocuments.in/reader033/viewer/2022060117/55847ec7d8b42aa9028b4729/html5/thumbnails/1.jpg)
![Page 2: 3rd hour](https://reader033.fdocuments.in/reader033/viewer/2022060117/55847ec7d8b42aa9028b4729/html5/thumbnails/2.jpg)
DNA REPLICATION Replication begins at special sites called
origin of replication
A stretch of DNA having a specific sequence of nucleotides
Protein that initiate DNA replication recognize this sequence and attach to the DNA
Two strands of DNA separate and opening up a replication ‘bubble’
![Page 3: 3rd hour](https://reader033.fdocuments.in/reader033/viewer/2022060117/55847ec7d8b42aa9028b4729/html5/thumbnails/3.jpg)
The Process Of DNA Replication
1)Unwound DNA strandEnzymes involved Function
DNA helicase enzymes
Separating the two strand of DNA
Helix-destabilizing proteins
bind to single DNA strand, preventing re-formation of the double helix until strands are
copied
Topoisomerase/girase
prevent the formation of knots during replication
![Page 4: 3rd hour](https://reader033.fdocuments.in/reader033/viewer/2022060117/55847ec7d8b42aa9028b4729/html5/thumbnails/4.jpg)
2. DNA Synthesized
Leading Strand
DNA synthesize: start from 5’ end 3’end toward replication fork.
![Page 5: 3rd hour](https://reader033.fdocuments.in/reader033/viewer/2022060117/55847ec7d8b42aa9028b4729/html5/thumbnails/5.jpg)
require an RNA primer first synthesised at the
point of initiation of replication.
Enzyme : primase
Then primase is displaced by DNA polymerase later will synthesize DNA.
![Page 6: 3rd hour](https://reader033.fdocuments.in/reader033/viewer/2022060117/55847ec7d8b42aa9028b4729/html5/thumbnails/6.jpg)
Ribonuclease will digest the RNA primer.
DNA replication is
continuous.
![Page 7: 3rd hour](https://reader033.fdocuments.in/reader033/viewer/2022060117/55847ec7d8b42aa9028b4729/html5/thumbnails/7.jpg)
Lagging strand
DNA synthesize: start from 5’ end
3’end Away from the
replication fork. DNA replication is
discontinuous.
![Page 8: 3rd hour](https://reader033.fdocuments.in/reader033/viewer/2022060117/55847ec7d8b42aa9028b4729/html5/thumbnails/8.jpg)
require an RNA primer first synthesized at the point of initiation of
replication. synthesized by a protein complex known
as primase.
Then primase is displaced by DNA polymerase later will synthesize DNA.
![Page 9: 3rd hour](https://reader033.fdocuments.in/reader033/viewer/2022060117/55847ec7d8b42aa9028b4729/html5/thumbnails/9.jpg)
Lagging Strand Only short piece
can be synthesize because DNA Polymerase would need to move far away from the fork.
These short segments called Okazaki fragments.
![Page 10: 3rd hour](https://reader033.fdocuments.in/reader033/viewer/2022060117/55847ec7d8b42aa9028b4729/html5/thumbnails/10.jpg)
2)DNA Synthesize (continue)
3’ end 5’end
Leading strand Lagging strand
Start synthesizing from the 3’ strand end
Start synthesizing from the 5’ strand end
*The fragment joined together by DNA ligase.*Lastly, two double helix strand are formed.
![Page 11: 3rd hour](https://reader033.fdocuments.in/reader033/viewer/2022060117/55847ec7d8b42aa9028b4729/html5/thumbnails/11.jpg)
![Page 12: 3rd hour](https://reader033.fdocuments.in/reader033/viewer/2022060117/55847ec7d8b42aa9028b4729/html5/thumbnails/12.jpg)
![Page 13: 3rd hour](https://reader033.fdocuments.in/reader033/viewer/2022060117/55847ec7d8b42aa9028b4729/html5/thumbnails/13.jpg)
Enzymes involved in DNA Replication DNA helicase : Unwind the double helix Primase : Synthesize RNA primer and
initiates the replication. DNA Polymerase : Synthesizes DNA. DNA Ligase : Joins the ends of DNA
segments.