Chapter 26, Problem 18P

What nonapeptide is coded for by the following fragment of mRNA?

5’—AAA—GUU—GGC—UAC—CCC—GGA—AUG—GUG—GUC—3’

Interpretation Introduction

Interpretation:

Nonapeptide which is coded for by the given strand of mRNA.

Concept introduction:

RNA is the abbreviation term of “Ribonucleic Acid”.  It is a complex molecule found in all living things.

RNA helps to make proteins.

Important RNAs such as messenger RNA (mRNA), $rRNA$ (ribosomal RNA) and $tRNA$ (transfer RNA) and their functions are mentioned below,

$\begin{array}{cc}\text{RNA}& \text{Function}\\ \text{mRNA}& \text{instructions}\text{to}\text{protein}\\ \text{rRNA}& \text{part}\text{of}\text{the}\text{ribosomes}\\ \text{tRNA}& \begin{array}{l}\text{carriers}\text{that}\text{match}\text{amino}\text{acids}\\ \text{to}\text{codons}\text{during}\text{translation}\end{array}\end{array}$

Codons are the sequence of three bases in mRNA that specifies the amino acid to be incorporated into a protein.

Some amino acids and their corresponding mRNA codons are listed below,

$\begin{array}{l}\begin{array}{cc}\text{Amino}{\text{acid}}^{\text{*}}& \text{mRNA}\text{codons}\\ \underset{\_}{\text{Ala}}\text{nine}& \text{GCU,GCC,GCA,GCG}\\ \underset{\_}{\text{Asp}}\text{aragine}& \text{GAU,GAC}\\ \underset{\_}{\text{Val}}\text{ine}& \text{GUU,GUC,GUA,GUG}\\ \underset{\_}{\text{His}}\text{tidine}& \text{CAU,CAC}\\ \underset{\_}{\text{Met}}\text{hionine}& \text{AUG}\\ \underset{\_}{\text{Cys}}\text{teine}& \text{UGU,UGC}\\ \underset{\_}{\text{Pro}}\text{line}& \text{CCU,CCC,CCA,CCG}\\ \underset{\_}{\text{Lys}}\text{ine}& \text{AAA,AAG}\\ \underset{\_}{\text{Gly}}\text{cine}& \text{GGU,GGC,GGA,GGG}\\ \underset{\_}{\text{Tyr}}\text{osine}& \text{UAU,UAC}\end{array}\\ \text{*}\text{The}\text{three}\text{letter}\text{code}\text{for}\text{each}\text{aminoacid}\text{is}\text{underlined}\text{.}\end{array}$

Anticodons are the matching sequence on the $tRNA$ to the codon on the mRNA.

A base is nitrogen containing heterocyclic compound which is found in DNA and RNA.

There are mainly four nitrogen bases in RNA.

1. (1) Adenine
2. (2) Guanine
3. (3) Cytosine
4. (4) Uracil

In RNA, Adenine always makes a double bond with uracil ($A=U$) and cytosine always makes triple bond with guanine $\left(G\equiv C\right)$

Answer to Problem 18P

Nonapeptide coded for given fragment is,

$Lys-Val-Gly-Tyr-\mathrm{Pr}o-Gly-Met-Val-Val$

Explanation of Solution

Some amino acids and their corresponding mRNA codons are listed below,

$\begin{array}{l}\begin{array}{cc}\text{Amino}{\text{acid}}^{\text{*}}& \text{mRNA}\text{codons}\\ \underset{\_}{\text{Ala}}\text{nine}& \text{GCU,GCC,GCA,GCG}\\ \underset{\_}{\text{Asp}}\text{aragine}& \text{GAU,GAC}\\ \underset{\_}{\text{Val}}\text{ine}& \text{GUU,GUC,GUA,GUG}\\ \underset{\_}{\text{His}}\text{tidine}& \text{CAU,CAC}\\ \underset{\_}{\text{Met}}\text{hionine}& \text{AUG}\\ \underset{\_}{\text{Cys}}\text{teine}& \text{UGU,UGC}\\ \underset{\_}{\text{Pro}}\text{line}& \text{CCU,CCC,CCA,CCG}\\ \underset{\_}{\text{Lys}}\text{ine}& \text{AAA,AAG}\\ \underset{\_}{\text{Gly}}\text{cine}& \text{GGU,GGC,GGA,GGG}\\ \underset{\_}{\text{Tyr}}\text{osine}& \text{UAU,UAC}\end{array}\\ \text{*}\text{The}\text{three}\text{letter}\text{code}\text{for}\text{each}\text{aminoacid}\text{is}\text{underlined}\text{.}\end{array}$

Given,

Strand of mRNA is,

$\text{5'-AAA-GUU-GGC-UAC-CCC-GGA-AUG-GUG-GUC-3'}$

Using the above table, the given mRNA fragment of $nonapeptide$ can be coded as,

$Lys-Val-Gly-Tyr-\mathrm{Pr}o-Gly-Met-Val-Val$

Conclusion

The $nonapeptide$ is coded for given strand of mRNA was given.