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Dna replication ?!

Please can you explain DNA REPLICATION , im doing as biology edexcel B, im really stuck, I watched many videos and read text books but I cant seem to understand. They talk about the ligase, dna polymerase, Rna primers and ozaki fragments etc.. please can can you explain it in detail but in simple. Thank You.


this is one of the spec point: UNDERSTAND HOW DNA IS REPICATED SEMI CONSERTIVLEY ,INCLUDING THE ROLE OF HELICASE, POLYMERASE,LIGASE (RNA PRIMERS just incase )

Thank You.:frown: Sorry for my bad grammar, im stressed over biology.
Reply 1
Avatar for arandom
arandom
Helicase unwind the DNA, then primase uses the DNA as a template to produce RNA primer, then the DNA polymerase extends the primerligase are there to join the pieces of DNA togetherUse the link below (it contains more than you need, just ignore the part you don't need)http://www.wiley.com/college/pratt/0471393878/student/animations/dna_replication/index.html
Reply 2
Avatar for sxah
sxah
1
Original post by DaraPark
Please can you explain DNA REPLICATION , im doing as biology edexcel B, im really stuck, I watched many videos and read text books but I cant seem to understand. They talk about the ligase, dna polymerase, Rna primers and ozaki fragments etc.. please can can you explain it in detail but in simple. Thank You.


this is one of the spec point: UNDERSTAND HOW DNA IS REPICATED SEMI CONSERTIVLEY ,INCLUDING THE ROLE OF HELICASE, POLYMERASE,LIGASE (RNA PRIMERS just incase )

Thank You.:frown: Sorry for my bad grammar, im stressed over biology.


1. The helicase unwinds the DNA strand so it is open and the nucleotide bases are open. DNA polymerase breaks the hydrogen bonds holding the nucleotides together.
2. This is gunna act as the template to make an identical copy for another strand of DNA. Which is basically what semi conservative replication is. It's using an original strand of DNA copied over to make a new identical copy.
3. Then the mRNA lays down the complimentary base pairs to match with the nucleotides. This occurs on both strands but in opposite directions which is how the double helix is formed. Osaka fragments usually don't come up in exams but they are basically fragments of where complimentary base pairing occurs on the newly created strand of DNA. A part of DNA is paired then the next part then the next. It all occurs in pieces hence the name fragment.
4. Once both strands have all the correct nucleotides attached they are 2 identical copies ready for the a mitosis, meiosis or protein synthesis.

Hope this helped.
If your still confused I suggest you watch this vid for a visual understanding
http://youtu.be/8kK2zwjRV0M
Reply 3
Avatar for Kingafy
Kingafy
I have this DNA problem solving coursework tomorrow, and our teacher says its going to be calculation based. I understand that base pairing is complementary and that the pairs A-T, C-G equal each other and to 100%. However, she has asked us why in some cases they might not equal to 100% percent or equal to one another. I have thought about mutations, intron, exons & stop codons but she has said they are incorrect. any help?
Reply 4
Avatar for sxah
sxah
1
I'v had this question come up before unfortunately I don't have the answer but the question will say something like. 70% of the pair is G what percent makes up C. Unfortunately it isn't as easy as saying 30% it's some long calcualtion to get the correct answer D:

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