Dna and mRNA

Genetics as it applies to evolution, molecular biology, and medical aspects.

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jschelbe
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Dna and mRNA

Post by jschelbe » Thu Jan 19, 2006 12:02 am

i am so confused. you have a strand of DNA...then the mRNA copies it - is the mRNA exactly like the DNA ( except that mRNA does not have t but has U in its place) or is the mRNA the "opposite' or matching or pairing ones?

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Jennifer
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mRNA

Post by Jennifer » Thu Jan 19, 2006 1:22 am

Hey,
When the template strand of DNA is coded, this produces mRNA. The mRNA is complementary to the template stand (however with urasil replacing thymine), and it is identical to the coding strand (the strand of DNA that was not copied).

Hope I helped!
~*Jennifer*~

aaroncjj_2020
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Post by aaroncjj_2020 » Fri Jan 20, 2006 9:07 am

actually it's depends on wat organism u are talking about.if it's a prokaryote(bacteria) then the mRNA is complementary to the DNA and the T is replace by U. but if u are refering to eukaryotic organism(human), our genes contain introns and exons.when the gene in the DNA is transcribed, pre-mRNA produced. pre-mRNA contain intron and exons.later the intron will be slice (cut) off and the mRNA now is not complementary to DNA anymore

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Nite
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Post by Nite » Sat Jan 21, 2006 12:51 pm

if the DNA is single stranded, the mRNA produced is complementary or similar to it will depend on the direction of the ssDNA..

For example: in human, our DNA is double stranded, with the strand running anti-parallel to each other i.e. one strand from 5' --> 3' and the other from 3' ---> 5'.

The 3' to 5' DNA strand is the one that is used as a template to produced a complementary mRNA (ie. 5' to 3'). Thus the mRNA produced will be same as the 5' to 3' DNA strand...

And now back to the question:

if the ssDNA is from 5' to 3' direction then the mRNA produced will be the same as it (note: a 3' to 5' DNA have to be synthesized before the mRNA can be transcripted).

If the ssDNA is 3' to 5', then the mRNA produced will be complementary to it..

taruna
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DNA and RNA

Post by taruna » Tue Jan 31, 2006 5:51 pm

Hey,

It depends if you talking abt prokaryotes then yes mRNA will be the exact copy of DNA except U at the place of T. But in eukaryotes first nascent transcript (pre RNA) of DNA is formed which also contain non coding regions(Introns). So some post trancriptnal modification such as splicing(removal of Introns) etc. will take place in RNA and then finally mRNA will be produced.
Hope it helped !!

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Post by sonam » Sat Feb 18, 2006 1:41 pm

IF U HAVE A PROBLEM WITH PROTEIN SYNTHESIS I HAVE A STORY FOR UT DO U WANT IT
IN SMALL PROPORTIONS WE MAY JUST BEAUTIES SEE
IN SHORT MEASURES LIFE CAN WONDERFUL BE

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Dr.Stein
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Post by Dr.Stein » Mon Feb 20, 2006 10:51 am

DON'T WRITE IN CAPS, DUDE!!! :evil: :twisted: :lol:
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