One strand of a section of DNA isolated from E. coli reads 5’ -GTAGCCTACCCATAGG-
ID: 94067 • Letter: O
Question
One strand of a section of DNA isolated from E. coli reads 5’ -GTAGCCTACCCATAGG-3’ A. Suppose that an mRNA were transcribed using the complement of this DNA strand as a template. What would the sequence of the mRNA in this region be? B. How many different peptides could potentially be made from this sequence of RNA? Would the same peptides be made if the other strand of DNA served as the template for transcription? C. What peptide would be made if translation started exactly at the 5/ end of the mRNA in Part A? When tRNAAla leaves the ribosome, what tRNA will be bound next? When the amino group of alanine forms a peptide bond, what bonds, if any, are broken, and what happens to tRNAAla?
Explanation / Answer
A. The complementary strand of the given strand would be 3'- CATCGGATGGGTATCC-5' , and now, the mRNA transcribed using this strand would be
5'-GUAGCCUACCCAUAGG-3' (in mRNA, all T has to be replaced with U)
B. Potentially three different poly-peptides could be made from this sequence of RNA considering three reading frames.
5'3' Frame 1
5'3' Frame 2
5'3' Frame 3
No, the same peptides wont be made if the other strand of DNA served as the template for transcription.
C. The peptide taht would be made if translation exactly started at 5' end of mRNA in part A would be the frame 1 of answer from part B, that is,
5'3' Frame 1
D) When Ala leaves the ribosome, Tyrosine (Y)tRNA (as evident from frame 1 result) will be bound next.
E) When the amino group of alanine forms a peptide bond, the covalent bond between alanine and its tRNA gets broken. After the formation of pepide bond, the tRNAAla moves back to the cytoplasm to pick up the next amino acid from the cytoplasmic pool.
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