Chapter 22, Problem 22.137EP

Consider the following DNA base sequence

$3\prime \text{TTA ATA}5\prime$

1. a. What dipeptide is formed from the transcription and translation of this DNA segment?
2. b. What dipeptide is formed if a DNA point mutation converts ATA to ATG?
3. c. What dipeptide is formed if a DNA point mutation converts ATA to AGA?
4. d. What dipeptide is formed if a DNA point mutation converts TTA to TTT?

Interpretation Introduction

Interpretation: The dipeptide that is formed by transcription of the given DNA segment has to be predicted.

Concept introduction: DNA stands for deoxyribonucleic acid, is a biological macromolecule.  DNA contains double helical strands along with the complementary base pairs.  The four complementary bases of DNA are adenine, thymine, guanine and cytosine.

A compound possessing two amino acids joined together by one peptide bond is known as dipeptide.  The amino acids present in the dipeptide are linked via peptide linkages.

Answer to Problem 22.137EP

The dipeptide that is formed by transcription of the given DNA segment is $\text{Asn}-\text{Tyr}$.

Explanation of Solution

The given DNA base sequence is,

    $3\text{'}\text{TTA}\text{ATA}5\text{'}$

The transcription of the above given DNA sequence forms the new hnRNA segment which is given as,

    $5\text{'}\text{AAU}\text{UAU}3\text{'}$

The amino acid that specifies the first codon, $\text{5'AAU3'}$ is asparagine $\left(\text{Asn}\right)$.

The amino acid that specifies the second codon, $\text{5'UAU3'}$ is tyrosine $\left(\text{Tyr}\right)$.

Thus, the amino acid sequence or dipeptide that is formed by transcription of the given DNA segment is $\text{Asn}-\text{Tyr}$.

Interpretation Introduction

Interpretation: The dipeptide that is formed if a point mutation converts $\text{ATA}$ to $\text{ATG}$ has to be predicted.

Concept introduction: DNA stands for deoxyribonucleic acid, is a biological macromolecule.  DNA contains double helical strands along with the complementary base pairs.  The four complementary bases of DNA are adenine, thymine, guanine and cytosine.

The process of permanently changing the nucleotide sequence of a genome of any organism is known as mutation.  In point mutation, one base is replaced by another base in the given base pair sequence.

Answer to Problem 22.137EP

The dipeptide that is formed if a point mutation converts $\text{ATA}$ to $\text{ATG}$ is $\text{Asn}-\text{Tyr}$.

Explanation of Solution

The given DNA base sequence is,

    $3\text{'}\text{TTA}\text{ATA}5\text{'}$

If point mutation occurs in the given DNA base sequence and converts $\text{ATA}$ to $\text{ATG}$ then the base sequence becomes,

    $3\text{'}\text{TTA}\text{ATG}5\text{'}$

The new codon formed after the base pairing is given as,

    $5\text{'}\text{AAU}\text{UAC}3\text{'}$

The amino acid that specifies the first codon, $\text{5'AAU3'}$ is asparagine $\left(\text{Asn}\right)$.

The amino acid that specifies the second codon, $\text{5'UAC3'}$ is tyrosine $\left(\text{Tyr}\right)$.

Thus, the amino acid sequence or dipeptide that is formed after the point mutation of the given DNA segment is $\text{Asn}-\text{Tyr}$.

Interpretation Introduction

Interpretation: The dipeptide that is formed if a point mutation converts $\text{ATA}$ to $\text{AGA}$ has to be predicted.

Concept introduction: DNA stands for deoxyribonucleic acid, is a biological macromolecule.  DNA contains double helical strands along with the complementary base pairs.  The four complementary bases of DNA are adenine, thymine, guanine and cytosine.

The process of permanently changing the nucleotide sequence of a genome of any organism is known as mutation.  In point mutation, one base is replaced by another base in the given base pair sequence.

Answer to Problem 22.137EP

The dipeptide that is formed if a point mutation converts $\text{ATA}$ to $\text{AGA}$ is $\text{Asn}-\text{Ser}$.

Explanation of Solution

The given DNA base sequence is,

    $3\text{'}\text{TTA}\text{ATA}5\text{'}$

If point mutation occurs in the given DNA base sequence and converts $\text{ATA}$ to $\text{AGA}$ then the base sequence becomes,

    $3\text{'}\text{TTA}\text{AGA}5\text{'}$

The new codon formed after the base pairing is given as,

    $5\text{'}\text{AAU}\text{UCU}3\text{'}$

The amino acid that specifies the first codon, $\text{5'AAU3'}$ is asparagine $\left(\text{Asn}\right)$.

The amino acid that specifies the second codon, $\text{5'UCU3'}$ is serine $\left(\text{Ser}\right)$.

Thus, the amino acid sequence or dipeptide that is formed after the point mutation of the given DNA segment is $\text{Asn}-\text{Ser}$.

Interpretation Introduction

Interpretation: The dipeptide that is formed if a point mutation converts $\text{TTA}$ to $\text{TTT}$ has to be predicted.

Concept introduction: DNA stands for deoxyribonucleic acid, is a biological macromolecule.  DNA contains double helical strands along with the complementary base pairs.  The four complementary bases of DNA are adenine, thymine, guanine and cytosine.

The process of permanently changing the nucleotide sequence of a genome of any organism is known as mutation.  In point mutation, one base is replaced by another base in the given base pair sequence.

Answer to Problem 22.137EP

The dipeptide that is formed if a point mutation converts $\text{TTA}$ to $\text{TTT}$ is $\text{Lys}-\text{Tyr}$.

Explanation of Solution

The given DNA base sequence is,

    $3\text{'}\text{TTA}\text{ATA}5\text{'}$

If point mutation occurs in the given DNA base sequence and converts $\text{TTA}$ to $\text{TTT}$ then the base sequence becomes,

    $3\text{'}\text{TTT}\text{ATA}5\text{'}$

The new codon formed after the base pairing is given as,

    $5\text{'}\text{AAA}\text{UAU}3\text{'}$

The amino acid that specifies the first codon, $\text{5'AAA3'}$ is Lysine $\left(\text{Lys}\right)$.

The amino acid that specifies the second codon, $\text{5'UAU3'}$ is tyrosine $\left(\text{Tyr}\right)$.

Thus, the amino acid sequence or dipeptide that is formed after the point mutation of the given DNA segment is $\text{Lys}-\text{Tyr}$.