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Old 12-24-2013
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Molecular What's the length of this mRNA?

A gene encodes a protein with 150 amino acids. There is one intron of 1000 bps a 5'-untranslated region of 100 bps and a 3'-untranslated region of 200 bp. In the final processed mRNA, how many bases lie between the start AUG codon and the final termination codon?

A. 1,750
B. 750
C. 650
D. 450
E. 150

kindly help me in this regard..i need answers with proper explanation.. in kaplan explanation is not that enough..
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Old 12-24-2013
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I think the answer is 450.

A processed, post tranceiptionally modified mRNA does not contain junk bases and contains bases that encode only one protein. Therefore 150 amino acids mean there should be 150 X 3 = 450 bases.

The 200 bases at the end should be the Poly-A tail to keep mRNA stable outside nucleus and it is attached AFTER the termination signal of 3 bases.

Hope this helps
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Quote:
Originally Posted by Leishmania View Post
I think the answer is 450.

A processed, post tranceiptionally modified mRNA does not contain junk bases and contains bases that encode only one pritein. Therefore 150 amino acids mean there should be 150 X 3 = 450 bases.

The 200 bases at the end should be the Poly-A tail to keep mRNA stable outside nucleus and it is attached AFTER the termination signal of 3 bases.

Hope this helps
thanks dats almost the explanation as kaplan .. i wonder where this 3 comes from? why we multiplied this with a 3?
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Quote:
Originally Posted by samreenkhowaja View Post
thanks dats almost the explanation as kaplan .. i wonder where this 3 comes from? why we multiplied this with a 3?
It takes 3 bases to code for 1 amino acid.. 150 amino acids means 150 X 3 bases in the mRNA.
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Quote:
Originally Posted by Leishmania View Post
It takes 3 bases to code for 1 amino acid.. 150 amino acids means 150 X 3 bases in the mRNA.
this worked.. thankuu sooooooooooo muchhhh.....
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Quote:
Originally Posted by samreenkhowaja View Post
this worked.. thankuu sooooooooooo muchhhh.....

No problems.. just make sure u get ur concepts right in future..
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Originally Posted by Leishmania View Post

No problems.. just make sure u get ur concepts right in future..
Yes I will
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Correct Answer

you must know that as post transcriptional modifications,
1. Splicing of introns by snmRNAs
2. Poly A tailing at 3' end
3. Addition of 7 methyl guanosine cap at 5' end

therfore, in this que, introns and all are given to misguide. just omit all of that and concentrate only on final proteins. 150*3=450

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