Chapter 24, Problem 80A

(a)

Interpretation Introduction

Interpretation: The amino acid sequence formed by translation of the DNA sequence GCC-CCA-ACG-TTA into a peptide is to be determined.

Concept Introduction: Each DNA strand is formed of a polynucleotide chain (phosphate groups, sugar units, and nitrogen bases), and these two strands form a double helix when wrapped in a spiral form. Adenine A, guanine G, thymine T, and cytosine C are the nitrogen bases found in DNA.

Answer to Problem 80A

Arg-Gly-Cys-Asn is the amino acid sequence formed by the translation of the DNA sequence -GCC-CCA-ACG-TTA into a peptide.

Explanation of Solution

The given DNA sequence is GCC-CCA-ACG-TTA.

A gene is a segment of DNA that includes the instructions for producing one peptide chain or protein, with three nitrogen bases of DNA necessary to define one amino acid for that chain.

The amino acid sequence is as follows:

• GCC is the code term for the amino acid Arg-arginine.
• CCA is the code term for the amino acid Gly-glycine.
• ACG is the code term for the amino acid Cys-cysteine.
• TTA is the code term for the amino acid Asn-asparagine.

Therefore, the amino acid sequence for the DNA sequence -GCC-CCA-ACG-TTA is Arg-Gly-Cys-Asn.

(b)

Interpretation Introduction

Interpretation: The amino acid sequence, the result of the substitution of adenine A for the second cytosine C in the DNA sequence GCC-CCA-ACG-TTA, is to determined.

Concept Introduction: Each DNA strand is formed of a polynucleotide chain (phosphate groups, sugar units, and nitrogen bases), and these two strands form a double helix when wrapped in a spiral form. Adenine A, guanine G, thymine T, and cytosine C are the nitrogen bases found in DNA

Answer to Problem 80A

Lue-Gly-Cys-Asn is the amino acid sequence formed by the substitution of adenine A for the second cytosine C in the DNA sequence GCC-CCA-ACG-TTA.

Explanation of Solution

The given DNA sequence is GCC-CCA-ACG-TTA.

The new sequence after the substitution of adenine A for the second cytosine C is GAC-CCA-ACG-TTA.

The amino acid sequence is as follows:

• GAC is the code term for the amino acid Lue-leucine.
• CCA is the code term for the amino acid Gly-glycine.
• ACG is the code term for the amino acid Cys-cysteine.
• TTA is the code term for the amino acid Asn-asparagine.

Therefore, the amino acid sequence for the DNA sequence -GAC-CCA-ACG-TTA is Lue-Gly-Cys-Asn.