Chapter 22, Problem 22.76P

Consider the following mRNA sequence: $\text{5-ACC UUA CGA-3’}$.

1. What amino acid sequence is coded for by this mRNA?
2. What is the amino acid sequence ¡f a mutation converts ACC to ACU?
3. What is the amino acid sequence if a mutation converts UUA to UCA?
4. What is the amino acid sequence if a mutation converts CGA to AGA?
5. What occurs if C is added to the beginning of the chain?

Interpretation Introduction

(a)

Interpretation:

Peptide synthesized by the 5' ACC UUA CGA 3' mRNA should be identified.

Concept Introduction:

DNA and RNA transform genetic information of the living cells through triplet code, which is a sequence of three nucleotides on DNA or RNA molecules codes for a specific amino acid in protein synthesis.

Answer to Problem 22.76P

Peptide − Thr-Leu-Arg

Explanation of Solution

Codons are written from 5 prime end (5) to 3 prime end (3) of mRNA. There is a unique triplet representation for a particular amino acid. Below mentioned table represent the relationship between nucleotides and amino acids.

The Genetic Code- Triplets in Messenger RNA

 

According to the above table; one amino acid has several triplets, but triplet code is unique for amino acid. ACC triplet is unique for Threonine. UUA triplet is unique for Leucine. CGA triplet is unique for Arginine.

Therefore, Thr-Leu-Arg is the amino acid sequence for 5' ACC UUA CGA 3'.

Interpretation Introduction

(b)

Interpretation:

Peptide formed from mutated mRNA5' ACU UUA CGA3' should be identified.

Concept Introduction:

DNA and RNA transform genetic information of the living cells through triplet code, which is a sequence of three nucleotides on DNA or RNA molecules codes for a specific amino acid in protein synthesis.

Mutation is an alteration of a sequence of nucleotides in DNA. Mutations can be classified based on the change that results in a DNA molecule.

Answer to Problem 22.76P

Peptide − Thr-Leu-Arg

Explanation of Solution

Mutation is an alteration of a sequence of nucleotides in DNA. When mutation happens at a particular position of a DNA molecule, that mutation goes through mRNA and translate a wrong peptide.

Mutations can be classified based on the change that results in a DNA molecule. There are three types of mutations which can be classified as follows;

1. Point mutations − A substitution of one nucleotide for another nucleotide.
2. Deletion mutations − One or more nucleotides is lost from a particular DNA molecule.
3. Insertion mutations − One or more nucleotides is added to a DNA molecule.

Codons are written from 5 prime end (5') to 3 prime end (3') of mRNA. There is a specific sequence of nucleotides for each amino acid. Below mentioned table represent the relationship between nucleotides and amino acids.

The Genetic Code- Triplets in Messenger RNA

 

According to the above table; one amino acid has several triplets, but triplet code is unique for amino acid. ACU triplet is unique for Threonine. UUA triplet is unique for Leucine. CGA triplet is unique for Arginine. Though there is a point mutation in the mRNA strand, in this example same peptide is generated as the non-mutated peptide. Therefore; this mutation has no effect with the generating peptide.

Therefore, Thr-Leu-Arg is the amino acid sequence for 5' ACU UUA CGA 3'.

Interpretation Introduction

(c)

Interpretation:

Peptide formed from mutated mRNA 5' ACC UCA CGA 3' should be identified.

Concept Introduction:

DNA and RNA transform genetic information of the living cells through triplet code, which is a sequence of three nucleotides on DNA or RNA molecules codes for a specific amino acid in protein synthesis.

Mutation is an alteration of a sequence of nucleotides in DNA. Mutations can be classified based on the change that results in a DNA molecule.

Answer to Problem 22.76P

Peptide − Thr-Ser-Arg.

Explanation of Solution

Mutation is an alteration of a sequence of nucleotides in DNA. When mutation happens at a particular position of a DNA molecule, that mutation goes through mRNA and translate a wrong peptide.

Mutations can be classified based on the change that results in a DNA molecule. There are three types of mutations which can be classified as follows;

1. Point mutations − A substitution of one nucleotide for another nucleotide.
2. Deletion mutations − One or more nucleotides is lost from a particular DNA molecule.
3. Insertion mutations − One or more nucleotides is added to a DNA molecule.

Codons are written from 5 prime end (5') to 3 prime end (3') of mRNA. There is a specific sequence of nucleotides for each amino acid. Below mentioned table represent the relationship between nucleotides and amino acids.

The Genetic Code- Triplets in Messenger RNA

 

According to the above table; one amino acid has several triplets, but triplet code is unique for amino acid. ACC triplet is unique for Threonine. UCA triplet is unique for Serine. CGA triplet is unique for Arginine. There is a point mutation in the mRNA strand, which UUA in the normal strand converts to UCA in the mutated strand. The resulting protein is different from the un-mutated one.

Therefore, Thr-Ser-Arg is the amino acid sequence for 5' ACC UCA CGA 3'.

Interpretation Introduction

(d)

Interpretation:

Peptide formed from mutated mRNA 5' ACC UCA CGA 3' should be identified.

Concept Introduction:

DNA and RNA transform genetic information of the living cells through triplet code, which is a sequence of three nucleotides on DNA or RNA molecules codes for a specific amino acid in protein synthesis.

Mutation is an alteration of a sequence of nucleotides in DNA. Mutations can be classified based on the change that results in a DNA molecule.

Answer to Problem 22.76P

Peptide − Thr-Leu-Arg

Explanation of Solution

Mutation is an alteration of a sequence of nucleotides in DNA. When mutation happens at a particular position of a DNA molecule, that mutation goes through mRNA and translate a wrong peptide.

Mutations can be classified based on the change that results in a DNA molecule. There are three types of mutations which can be classified as follows;

1. Point mutations − A substitution of one nucleotide for another nucleotide.
2. Deletion mutations − One or more nucleotides is lost from a particular DNA molecule.
3. Insertion mutations − One or more nucleotides is added to a DNA molecule.

Codons are written from 5 prime end (5') to 3 prime end (3') of mRNA. There is a specific sequence of nucleotides for each amino acid. Below mentioned table represent the relationship between nucleotides and amino acids.

The Genetic Code- Triplets in Messenger RNA

 

According to the above table; one amino acid has several triplets, but triplet code is unique for amino acid. ACC triplet is unique for Threonine. UUA triplet is unique for Leucine. AGA triplet is unique for Arginine. There is a point mutation in the mRNA strand, which CGA in the normal strand converts to AGA in the mutated strand. Though there is a point mutation in the mRNA strand, in this example same peptide is generated as the non-mutated peptide. Therefore; this mutation has no effect with the generating peptide.

Therefore, Thr-Leu-Arg is the amino acid sequence for 5' ACC UUA AGA 3'.

Interpretation Introduction

(e)

Interpretation:

Peptide formed from mutated mRNA 5' CACC UUA CGA 3' should be identified.

Concept Introduction:

DNA and RNA transform genetic information of the living cells through triplet code, which is a sequence of three nucleotides on DNA or RNA molecules codes for a specific amino acid in protein synthesis.

Mutation is an alteration of a sequence of nucleotides in DNA. Mutations can be classified based on the change that results in a DNA molecule.

Answer to Problem 22.76P

Peptide − His-Leu-Thr

Explanation of Solution

Mutation is an alteration of a sequence of nucleotides in DNA. When mutation happens at a particular position of a DNA molecule, that mutation goes through mRNA and translate a wrong peptide.

Mutations can be classified based on the change that results in a DNA molecule. There are three types of mutations which can be classified as follows;

1. Point mutations − A substitution of one nucleotide for another nucleotide.
2. Deletion mutations − One or more nucleotides is lost from a particular DNA molecule.
3. Insertion mutations − One or more nucleotides is added to a DNA molecule.

Codons are written from 5 prime end (5') to 3 prime end (3') of mRNA. There is a specific sequence of nucleotides for each amino acid. Below mentioned table represent the relationship between nucleotides and amino acids.

The Genetic Code- Triplets in Messenger RNA

 

According to the above table; one amino acid has several triplets, but triplet code is unique for amino acid. Codons are written from 5 prime end (5') to 3 prime end (3') of mRNA and read as triplets, because of the insertion mutation which occurred here because of additional C in the beginning of the mRNA, triplets are read as follows. CAC triplet is for Histidine, CUU is for Leucine and ACG is for Threonine. Furthermore, there is an additional A nucleotide, which is not involved into this peptide. This mutation generates totally different peptide and generated peptide is as follows; His-Leu-Thr is the amino acid sequence for 5' CAC CUU A AG A 3'.