Question
Cystic fibrosis is caused by a mutation in a gene involved in plasma membranes. The image shows the amino acid sequences coded by a normal and a mutated gene.
Normal Sequence: VALINE-HISTIDINE-LEUCINE-THREONINE-PROLINE-GLUTAMIC ACID-GLUTAMIC ACID
Mutated Sequence: VALINE-HISTIDINE-LEUCINE-THREONINE--ALANINE-TRYPTOPHAN
Analyze the sequences and select the option which best describes the change in the DNA sequence of the gene coding for the mutated protein.
Responses
A base pair is added in the DNA sequence
A base pair is added in the DNA sequence
A base pair is replaced in the DNA sequence
A base pair is replaced in the DNA sequence
A base pair is deleted in the DNA sequence
A base pair is deleted in the DNA sequence
A base pair is translocated in the DNA sequence.
Normal Sequence: VALINE-HISTIDINE-LEUCINE-THREONINE-PROLINE-GLUTAMIC ACID-GLUTAMIC ACID
Mutated Sequence: VALINE-HISTIDINE-LEUCINE-THREONINE--ALANINE-TRYPTOPHAN
Analyze the sequences and select the option which best describes the change in the DNA sequence of the gene coding for the mutated protein.
Responses
A base pair is added in the DNA sequence
A base pair is added in the DNA sequence
A base pair is replaced in the DNA sequence
A base pair is replaced in the DNA sequence
A base pair is deleted in the DNA sequence
A base pair is deleted in the DNA sequence
A base pair is translocated in the DNA sequence.
Answers
GPT-4o mini
To analyze the change in the amino acid sequences between the normal and mutated versions, we can examine the differences.
- **Normal Sequence**: VALINE-HISTIDINE-LEUCINE-THREONINE-PROLINE-GLUTAMIC ACID-GLUTAMIC ACID
- **Mutated Sequence**: VALINE-HISTIDINE-LEUCINE-THREONINE-ALANINE-TRYPTOPHAN
In the mutated sequence, after "THREONINE," we see:
- The normal sequence has "PROLINE," while the mutated sequence has "ALANINE."
- Following "ALANINE," the normal sequence has "GLUTAMIC ACID," but the mutated sequence has "TRYPTOPHAN."
This indicates that two amino acids in the mutated sequence are different from the normal sequence.
This change likely involves a substitution in the DNA sequence, where the codons corresponding between the normal and mutated sequences differ:
- The base pairs that code for "PROLINE" have been changed to those that code for "ALANINE."
- The base pairs that code for the subsequent "GLUTAMIC ACID" have changed to those that code for "TRYPTOPHAN."
Since two amino acids were altered, the simplest explanation is that one or more base pairs were replaced in the DNA sequence.
Therefore, the best option is:
**A base pair is replaced in the DNA sequence.**
- **Normal Sequence**: VALINE-HISTIDINE-LEUCINE-THREONINE-PROLINE-GLUTAMIC ACID-GLUTAMIC ACID
- **Mutated Sequence**: VALINE-HISTIDINE-LEUCINE-THREONINE-ALANINE-TRYPTOPHAN
In the mutated sequence, after "THREONINE," we see:
- The normal sequence has "PROLINE," while the mutated sequence has "ALANINE."
- Following "ALANINE," the normal sequence has "GLUTAMIC ACID," but the mutated sequence has "TRYPTOPHAN."
This indicates that two amino acids in the mutated sequence are different from the normal sequence.
This change likely involves a substitution in the DNA sequence, where the codons corresponding between the normal and mutated sequences differ:
- The base pairs that code for "PROLINE" have been changed to those that code for "ALANINE."
- The base pairs that code for the subsequent "GLUTAMIC ACID" have changed to those that code for "TRYPTOPHAN."
Since two amino acids were altered, the simplest explanation is that one or more base pairs were replaced in the DNA sequence.
Therefore, the best option is:
**A base pair is replaced in the DNA sequence.**