Chapter 15.2, Problem 29AQP

a.

Summary Introduction

To determine:

The position of the codon in the mRNA that must be altered by which Leucine is converted to glutamine. ($\text{Leu}\to \text{Gln}$). Also, determine the amino acid that could result from a mutation at a single base.

Introduction:

The basic unit of genetic code is called a codon. The genetic code is a triplet code, in which three nucleotides encode each amino acid in a protein. The genetic code has sixty-one codons that specify the twenty amino acids. The degeneracy of genetic code means that the code is redundant and the amino acids may be specified by more than one codon.

Tryptophan and methionine are the only amino acids that are encoded by a single codon.

Explanation of Solution

The codon table represents the codons and coded amino acids:

The codon table shows that the amino acid Leucine (Leu) is specified by six codons CUU, CUC, CUA, CUG, UAA, and UUG. The amino acid glutamine is specified by only two codons CAA and CAG.

The codons of glutamine could be developed by mutation of two codons of Leucine that includes CUA and CUG. The mutation occurs at a single base position in the codon.

$\text{CUG}\text{(Leu)}\to \text{CAG(Gln)}$, the nucleotide U at the second position of leucine is mutated to A, which form CAG that encodes glutamine (Gln).

$\text{CUA(Leu)}\to \text{CAA(Gln)}$, the nucleotide U at the second position of leucine is mutated to A, which form CAA that encodes glutamine (Gln).

b.

Summary Introduction

To determine:

The position of the codon in the mRNA that must be altered by which phenylalanineis converted to serine $\text{Phe}\to \text{Ser}$. Also, determine the amino acid that could result from a mutation at a single base.

Introduction:

The basic unit of genetic code is called a codon. The genetic code is a triplet code, in which three nucleotides encode each amino acid in a protein. The genetic code has sixty-one codons that specify the twenty amino acids. The degeneracy of genetic code means that the code is redundant and the amino acids may be specified by more than one codon.

Tryptophan and methionine are the only amino acids that are encoded by a single codon.

Explanation of Solution

The codon table represents the codons and coded amino acids:

The codon table shows that the amino acid phenylalanine (Phe) is specified by onlytwo codons UUU and UUC. The amino acid serine (Ser) is specified by four codons UCA, UCC, UCA,andUCG.

The codons of serine could be developed by mutation of both codons of phenylalaninethat includes UUU and UUC. The mutation occurs at a single base position in the codon.

$\text{UUU}\text{(Phe)}\to \text{UCU(Ser)}$, the nucleotide U at the second position of phenylalanine is mutated to C, which forms UCU that encodes serine (Ser).

$\text{UUC(Phe)}\to \text{UCC(Ser)}$, the nucleotide U at the second position of phenylalanine is mutated to C, which forms UCC that encodes serine (Ser).

c.

Summary Introduction

To determine:

The position of the codon in the mRNA that must be altered by which phenylalanine is converted to isoleucine $\text{Phe}\to \text{Ile}$. Also, determine the amino acid that could result from a mutation at a single base.

Introduction:

The basic unit of genetic code is called a codon. The genetic code is a triplet code, in which three nucleotides encode each amino acid in a protein. The genetic code has sixty-one codons that specify the twenty amino acids. The degeneracy of genetic code means that the code is redundant and the amino acids may be specified by more than one codon.

Tryptophan and methionine are the only amino acids that are encoded by a single codon.

Explanation of Solution

The codon table represents the codons and coded amino acids:

The codon table shows that the amino acid phenylalanine (Phe) is specified by only two codons UUU and UUC. The amino acid isoleucine (Ile) is specified by three codons AUU, AUC, and AUA.

The codons of isoleucine could be developed by mutation of both codons of phenylalanine that includes UUU and UUC. The mutation occurs at a single base position in the codon.

$\text{UUU}\text{(Phe)}\to \text{AUU(Ile)}$, the nucleotide U at the first position of phenylalanine is mutated to A, which form AUU that encodes isoleucine (Ile).

$\text{UUC(Phe)}\to \text{AUC(Ile)}$, the nucleotide U at the first position of phenylalanine is mutated to A, which form AUC that encodes isoleucine (Ile).

d.

Summary Introduction

To determine:

The position of the codon in the mRNA that must be altered by which proline is converted to alanine $\text{Pro}\to \text{Ala}$. Also, determine the amino acid that could result from a mutation at a single base.

Introduction:

The basic unit of genetic code is called a codon. The genetic code is a triplet code, in which three nucleotides encode each amino acid in a protein. The genetic code has sixty-one codons that specify the twenty amino acids. The degeneracy of genetic code means that the code is redundant and the amino acids may be specified by more than one codon.

Tryptophan and methionine are the only amino acids that are encoded by a single codon.

Explanation of Solution

The codon table represents the codons and coded amino acids:

The codon table shows that the amino acid proline (Pro) is specified byfour codons CCU, CCA, CCC, and CCG. The amino acid alanine (Ala) is specified by GCU, GCG, GCC, and GCA.

The codons of alanine could be developed by mutation of all codons of proline that includes CCU, CCA, CCC, and CCG. The mutation occurs at a single base position in the codon.

$\text{CCU}\text{(Pro)}\to \text{GCU(Ala)}$, the nucleotide C at the first position of proline is mutated to G, which form GCU that encodes alanine (Ala).

$\text{CCC(Pro)}\to \text{GCC(Ala)}$, the nucleotide C at the first position of proline is mutated to G, which form GCC that encodes alanine (Ala).

$\text{CCA(Pro)}\to \text{GCA(Ala)}$, the nucleotide C at the first position of proline is mutated to G, which form GCA that encodes alanine (Ala).

$\text{CCG(Pro)}\to \text{GCG(Ala)}$, the nucleotide C at the first position of proline is mutated to G, which form GCG that encodes alanine (Ala).

e.

Summary Introduction

To determine:

The position of the codon in the mRNA that must be altered by which asparagine is converted to lysine $\text{Asn}\to \text{Lys}$. Also, determine the amino acid that could result from a mutation at a single base.

Introduction:

The basic unit of genetic code is called a codon. The genetic code is a triplet code, in which three nucleotides encode each amino acid in a protein. The genetic code has sixty-one codons that specify the twenty amino acids. The degeneracy of genetic code means that the code is redundant and the amino acids may be specified by more than one codon.

Tryptophan and methionine are the only amino acids that are encoded by a single codon.

Explanation of Solution

The codon table represents the codons and coded amino acids:

The codon table shows that the amino acid asparagine (Asn) is specified by two codons AAU and AAC. The amino acid lysine is specified by the codons AAA and AAG.

The codons of lysine could be developed by mutation of bothcodons of asparagine that includes AAU and AAC. The mutation occurs at a single base position in the codon.

$\text{AAU}\text{(Asn)}\to \text{AAA(Lys)}$, the nucleotide U at the third position of asparagine is mutated to A, which form AAA that encodes lysine (Lys).

$\text{AAC(Asn)}\to \text{AAG(Lys)}$, the nucleotide C at the third position of asparagine is mutated to G, which form AAG that encodes lysine (Lys).

f.

Summary Introduction

To determine:

The position of the codon in the mRNA that must be altered by which isoleucine is converted to asparagine $\text{Ile}\to \text{Asn}$. Also, determine the amino acid that could result from a mutation at a single base.

Introduction:

The basic unit of genetic code is called a codon. The genetic code is a triplet code, in which three nucleotides encode each amino acid in a protein. The genetic code has sixty-one codons that specify the twenty amino acids. The degeneracy of genetic code means that the code is redundant and the amino acids may be specified by more than one codon.

Tryptophan and methionine are the only amino acids that are encoded by a single codon.

Explanation of Solution

The codon table represents the codons and coded amino acids:

The codon table shows that the amino acid isoleucine (Ile) is specified by three codons AUU, AUC, and AUA. The amino acid asparagine is specified by the codons AAU and AAC

The codons of asparagine could be developed by mutation of only two codons of isoleucine that includes AUU and AUC. The mutation occurs at a single base position in the codon.

$\text{AUU}\text{(Ile)}\to \text{AAU(Asn)}$, the nucleotide U at the second position of isoleucine is mutated to A, which form AAU that encodes asparagine (Asp).

$\text{AUC(Ile)}\to \text{AAC(Asn)}$, the nucleotide U at the second position of isoleucine is mutated to A, which form AAC that encodes asparagine (Asn).