For all the Geneticists in Da house.

bleeb

Lifer
Feb 3, 2000
10,868
0
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So in the S phase of Interphase, during DNA replication when the helicase enzymes untwist the DNA helix structures, replication forks appear; then NEW DNA strands are formed from the template, but HOW does the helicase enzyme know NOT to untwist on the duplicated DNA strand (the New strand)? In essense, how does it know NOT to replicate the duplicate?
 

NikPreviousAcct

No Lifer
Aug 15, 2000
52,763
1
0
The helicase enzyme is probably like Neo where he can see people actually built out of matrix code and some people are significant enough to glow different colors an'sh|t.

:p

I dunno, just need something to do while I wait around for my coworker to be able to leave so we can go grab some grub. Good luck. :)
 

Sgt.Speculum

Member
Oct 9, 1999
188
0
0
Newly synthesized DNA is not methylated. So the cell has the ability to distinguish between newly synthesized DNA and template DNA. I'm pretty sure, but if I'm wrong, someone feel free to correct me.

Ian

Also the helicase only unwinds DNA, DNA polymerase replicates the DNA
 

bleeb

Lifer
Feb 3, 2000
10,868
0
0
Originally posted by: Nik
The helicase enzyme is probably like Neo where he can see people actually built out of matrix code and some people are significant enough to glow different colors an'sh|t.

:p

I dunno, just need something to do while I wait around for my coworker to be able to leave so we can go grab some grub. Good luck. :)

You are definitely NOT new to the idea of NEFFING! NEFFER! :p
 

bleeb

Lifer
Feb 3, 2000
10,868
0
0
Originally posted by: Sgt.Speculum
Newly synthesized DNA is not methylated. So the cell has the ability to distinguish between newly synthesized DNA and template DNA. I'm pretty sure, but if I'm wrong, someone feel free to correct me.

Ian

I'm not familiar with methylated? What does that mean?
 

NikPreviousAcct

No Lifer
Aug 15, 2000
52,763
1
0
Originally posted by: bleeb
Originally posted by: Nik
The helicase enzyme is probably like Neo where he can see people actually built out of matrix code and some people are significant enough to glow different colors an'sh|t.

:p

I dunno, just need something to do while I wait around for my coworker to be able to leave so we can go grab some grub. Good luck. :)

You are definitely NOT new to the idea of NEFFING! NEFFER! :p

Text
Enjoy
 

bleeb

Lifer
Feb 3, 2000
10,868
0
0
Originally posted by: Nik
Originally posted by: bleeb
Originally posted by: Nik
The helicase enzyme is probably like Neo where he can see people actually built out of matrix code and some people are significant enough to glow different colors an'sh|t.

:p

I dunno, just need something to do while I wait around for my coworker to be able to leave so we can go grab some grub. Good luck. :)

You are definitely NOT new to the idea of NEFFING! NEFFER! :p

Text
Enjoy

hahah but I'm No Noob big dawg.

It's Official!
 

Mo0o

Lifer
Jul 31, 2001
24,227
3
76
The new strand is alreayd covalently bonded to the template strand so theres no replication
 

jagec

Lifer
Apr 30, 2004
24,442
6
81
Originally posted by: bleeb
Originally posted by: Sgt.Speculum
Newly synthesized DNA is not methylated. So the cell has the ability to distinguish between newly synthesized DNA and template DNA. I'm pretty sure, but if I'm wrong, someone feel free to correct me.

Ian

I'm not familiar with methylated? What does that mean?

It has methyl groups attached to it. It's been a while since I took biology, so I don't know when or how they appear.
 

bleeb

Lifer
Feb 3, 2000
10,868
0
0
Originally posted by: Mo0o
The new strand is alreayd covalently bonded to the template strand so theres no replication

Yes, but helicase enzymes untwist the strands so they can be separated for replication...but what stops them from untwisting the replicated strands and replicating the duplicates? A suggested answer was methylation but I don't know exactly what that is.
 

Gibsons

Lifer
Aug 14, 2001
12,530
35
91
Originally posted by: Sgt.Speculum
Newly synthesized DNA is not methylated. So the cell has the ability to distinguish between newly synthesized DNA and template DNA. I'm pretty sure, but if I'm wrong, someone feel free to correct me.

Ian

Also the helicase only unwinds DNA, DNA polymerase replicates the DNA


This is essentially correct. Especially the polymerase part.

Edit: methylation is when a methyl group (-CH3) gets covalently attached to a molecule (a base in this case). Sometimes cytosine gets methylated to form 5-methyl cytosine for instance.
 

Siva

Diamond Member
Mar 8, 2001
5,472
0
71
The DNA polymerase replicates the strand, and then DNA ligase stiches fragments together. When helicase is attaching, there is no new strand to attach to. Plus, why would replication start on the new, incomplete strand when its already begun on the old one?

methylated? maybe i'm wrong, i dunno, i'm retarted. this stuff's a semester old already
 

bleeb

Lifer
Feb 3, 2000
10,868
0
0
Originally posted by: Gibsons
Originally posted by: Sgt.Speculum
Newly synthesized DNA is not methylated. So the cell has the ability to distinguish between newly synthesized DNA and template DNA. I'm pretty sure, but if I'm wrong, someone feel free to correct me.

Ian

Also the helicase only unwinds DNA, DNA polymerase replicates the DNA


This is essentially correct. Especially the polymerase part.

Several enzymes work together to replicate the new strand but what exactly happens during methylation? A methyl group gets attached? To the DNA?
 

Gibsons

Lifer
Aug 14, 2001
12,530
35
91
er see my edit above.

When DNA gets replicated, the old DNA has methyl groups, but the new DNA does not. So you have a methylated strand annealed to a non-methylated strand. Duplex DNA in this state is said to be "hemi-methylated." There are specific proteins which recognize hemi-methylated DNA.

To answer your question more directly, there are specific origins of replication within a genome. There's a loose sequence conservation among them iirc, but it's probably more complicated than that. Anyway, when the signal to replicate is given, just those spots are opened up, and the DNA polymerase machinery jumps in. As long as each origin is only used once, you should get just one round of replication.