## RF and DNA fragment

Discussion of all aspects of biological molecules, biochemical processes and laboratory procedures in the field.

kitty2
Garter
Posts: 5
Joined: Wed Dec 14, 2005 6:07 pm

### RF and DNA fragment

If I am given the RF let say .7, and there is an equation (use any example of equation, you like) for the threadline in the graph. Then the RF is on the y axis. The log 10 base pair is on the x axis.

How do I find the lenght of a DNA fragment? This is confusing. How do I do this?

canalon
Inland Taipan
Posts: 3909
Joined: Thu Feb 03, 2005 2:46 pm
Easy... if you first have a reference curve (set of DNA fragments with known molecular weight and their RF) You just plot them on your graph, make sure that your fragment is in the range of the marker (It is not really recommended to extrapolate a curve beyond the extreme reference points) and you just read the X vale for your given Y et voila
Patrick

Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)

kitty2
Garter
Posts: 5
Joined: Wed Dec 14, 2005 6:07 pm
But I don't know the molecular weight. You mean that the molecular weight of RF .7 is 5.01?

Yes, but this assignment does not give me the molecularweight. It is only a graph, and it give me:
RF
Log10 Base Pair
the equation of the tread line

If I have the RF value and the y=.89834x-.3984
Then how would I find the length of the base pair? I do not understnad. Make it simple for me. Is the molecularweight the basepair?

kitty2
Garter
Posts: 5
Joined: Wed Dec 14, 2005 6:07 pm
You mean that the x axis that said, 'log10 base pair' is really the lenght of a DNA fragment?

Then why is the x axis called 'log10 base pair'?

canalon
Inland Taipan
Posts: 3909
Joined: Thu Feb 03, 2005 2:46 pm
Yes MW and Bp are synonimous here.
And if you have all that you just have to solve the equation for y=0.7 and you got log10(Bp), so by calculating 10^[log10(Bp)] you end up with your result.
Patrick

Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)

kitty2
Garter
Posts: 5
Joined: Wed Dec 14, 2005 6:07 pm
I was not given the MW.
When I slove the equation, with the RF as Y in the equation, I get a 3 digest numbers. And when I try to anti log that, I get an error.

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