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Ch. 11 - Gene Mutation, DNA Repair, and Homologous Recombination
Sanders - Genetic Analysis: An Integrated Approach 3rd Edition
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook
All textbooksSanders 3rd EditionCh. 11 - Gene Mutation, DNA Repair, and Homologous RecombinationProblem 20b
Chapter 11, Problem 20b

The partial amino acid sequence of a wild-type protein is
… Arg-Met-Tyr-Thr-Leu-Cys-Ser …
The same portion of the protein from a mutant has the sequence
… Arg-Met-Leu-Tyr-Ala-Leu-Phe …
Give the sequence of the wild-type DNA template strand. Use A/G if the nucleotide could be either purine, T/C if it could be either pyrimidine, N if any nucleotide could occur at a site, or the alternative nucleotides if a purine and a pyrimidine are possible.

Verified step by step guidance
1
Step 1: Understand the relationship between amino acids and codons. Each amino acid is encoded by a three-nucleotide sequence called a codon. Use the genetic code table to determine the possible codons for each amino acid in the wild-type protein sequence.
Step 2: Translate the wild-type amino acid sequence (Arg-Met-Tyr-Thr-Leu-Cys-Ser) into its corresponding mRNA codons. For example, Arg can be encoded by CGU, CGC, CGA, or CGG; Met is encoded by AUG; and so on. Identify all possible codons for each amino acid.
Step 3: Convert the mRNA codons into the complementary DNA coding strand sequence. Remember that in DNA, A pairs with T, and G pairs with C. For example, AUG in mRNA corresponds to TAC in the DNA coding strand.
Step 4: Determine the DNA template strand sequence by taking the complement of the DNA coding strand. For example, if the coding strand has TAC, the template strand will have ATG. This is the strand used during transcription to produce the mRNA.
Step 5: Use the notation A/G, T/C, or N for ambiguous nucleotide positions where multiple codons could encode the same amino acid. For example, if Arg can be encoded by CGU, CGC, CGA, or CGG, the corresponding DNA template strand might include positions with A/G or T/C to reflect the ambiguity.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Genetic Code

The genetic code is a set of rules that defines how the sequence of nucleotides in DNA corresponds to the sequence of amino acids in proteins. Each amino acid is encoded by a specific triplet of nucleotides, known as a codon. Understanding the genetic code is essential for translating the amino acid sequences back into their corresponding DNA sequences.
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DNA Template Strand

The DNA template strand is the strand of DNA that serves as a template for RNA synthesis during transcription and for DNA replication. It is complementary to the coding strand and dictates the sequence of nucleotides in the newly synthesized strand. Knowing how to derive the template strand from an amino acid sequence is crucial for solving the given problem.
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Mutations and Their Effects

Mutations are changes in the nucleotide sequence of DNA that can lead to alterations in protein structure and function. Understanding the types of mutations, such as substitutions, insertions, or deletions, is important for analyzing differences between wild-type and mutant protein sequences. This knowledge helps in predicting how these changes might affect the corresponding DNA sequences.
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Related Practice
Textbook Question

Using the adenine–thymine base pair in this DNA sequence

...GCTC...

...CGAG...

Give the sequence after a transition mutation.

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Textbook Question

Using the adenine–thymine base pair in this DNA sequence

...GCTC...

...CGAG...

Give the sequence after a transversion mutation.

628
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Textbook Question

The partial amino acid sequence of a wild-type protein is

… Arg-Met-Tyr-Thr-Leu-Cys-Ser …

The same portion of the protein from a mutant has the sequence

… Arg-Met-Leu-Tyr-Ala-Leu-Phe …

Identify the type of mutation.

714
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Textbook Question

The two DNA and polypeptide sequences shown are for alleles at a hypothetical locus that produce different polypeptides, both five amino acids long. In each case, the lower DNA strand is the template strand:

Based on DNA and polypeptide sequences alone, is there any way to determine which allele is dominant and which is recessive? Why or why not?

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Textbook Question

Many human genes are known to have homologs in the mouse genome. One approach to investigating human hereditary disease is to produce mutations of the mouse homologs of human genes by methods that can precisely target specific nucleotides for mutation.

Numerous studies of mutations of the mouse homologs of human genes have yielded valuable information about how gene mutations influence the human disease process. In general terms, describe how and why creating mutations of the mouse homologs can give information about human hereditary disease processes.

734
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Textbook Question

Many human genes are known to have homologs in the mouse genome. One approach to investigating human hereditary disease is to produce mutations of the mouse homologs of human genes by methods that can precisely target specific nucleotides for mutation.

Despite the homologies that exist between human and mouse genes, some attempts to study human hereditary disease processes by inducing mutations in mouse genes indicate there is little to be learned about human disease in this way. In general terms, describe how and why the study of mouse gene mutations might fail to produce useful information about human disease processes.

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