Podcast
Questions and Answers
Which of the following best describes a transition mutation at the DNA level?
Which of the following best describes a transition mutation at the DNA level?
- A change from a purine to a pyrimidine base.
- An insertion or deletion of a single nucleotide base.
- A change between two purines or between two pyrimidines. (correct)
- A change from a pyrimidine to a purine base.
A mutation occurs where a codon for serine (UCU) is changed to a codon for proline (CCA). What type of point mutation is this?
A mutation occurs where a codon for serine (UCU) is changed to a codon for proline (CCA). What type of point mutation is this?
- Nonsense mutation
- Silent mutation
- Missense mutation (correct)
- Transition mutation
Which type of mutation results in a premature stop codon within the mRNA sequence?
Which type of mutation results in a premature stop codon within the mRNA sequence?
- Silent mutation
- Transversion mutation
- Nonsense mutation (correct)
- Missense mutation
What is the most likely effect of a frameshift mutation resulting from the insertion of a single nucleotide base in the middle of a coding sequence?
What is the most likely effect of a frameshift mutation resulting from the insertion of a single nucleotide base in the middle of a coding sequence?
A silent mutation is least likely to alter which of the following?
A silent mutation is least likely to alter which of the following?
Which of the following is a characteristic of a transversion mutation?
Which of the following is a characteristic of a transversion mutation?
In the context of protein function, what characterizes a 'partially acceptable' missense mutation?
In the context of protein function, what characterizes a 'partially acceptable' missense mutation?
How does the degeneracy of the genetic code influence the occurrence of silent mutations?
How does the degeneracy of the genetic code influence the occurrence of silent mutations?
What is the primary consequence of deleting three consecutive nucleotides within the coding region of a gene?
What is the primary consequence of deleting three consecutive nucleotides within the coding region of a gene?
Which scenario is most likely to result from the insertion of a single nucleotide near the beginning of the coding sequence of a gene?
Which scenario is most likely to result from the insertion of a single nucleotide near the beginning of the coding sequence of a gene?
Which type of mutation is least likely to have a significant effect on the phenotype of an organism?
Which type of mutation is least likely to have a significant effect on the phenotype of an organism?
If a mutation causes a change in the codon from GAU to GAC, what is the likely effect on the protein, considering both codons code for aspartic acid?
If a mutation causes a change in the codon from GAU to GAC, what is the likely effect on the protein, considering both codons code for aspartic acid?
A scientist discovers that a point mutation in a gene results in a protein that is twice as long as the normal protein. What type of mutation is the most likely cause?
A scientist discovers that a point mutation in a gene results in a protein that is twice as long as the normal protein. What type of mutation is the most likely cause?
Which of the following mutations would likely have the least severe impact on protein function?
Which of the following mutations would likely have the least severe impact on protein function?
What would be the effect of a mutation that disrupts the normal termination codons?
What would be the effect of a mutation that disrupts the normal termination codons?
A mutation in the coding sequence of a gene changes a single nucleotide, but the resulting protein sequence is identical to the wild-type protein. This is an example of what type of mutation?
A mutation in the coding sequence of a gene changes a single nucleotide, but the resulting protein sequence is identical to the wild-type protein. This is an example of what type of mutation?
A researcher is studying a protein and discovers that a mutation has caused one of the original alanine amino acids to be replaced by a valine. What is the most likely type of mutation that caused this change?
A researcher is studying a protein and discovers that a mutation has caused one of the original alanine amino acids to be replaced by a valine. What is the most likely type of mutation that caused this change?
A scientist is investigating a bacterial strain with a mutation that arose due to the insertion of one pyrimidine base in the DNA. What kind of mutation is this?
A scientist is investigating a bacterial strain with a mutation that arose due to the insertion of one pyrimidine base in the DNA. What kind of mutation is this?
Which of the following statements best characterizes the effects of insertion?
Which of the following statements best characterizes the effects of insertion?
A scientist discovers that a mutation has occurred during the deletion of 3 consecutive nucleotides. What is its effect on amino acids?
A scientist discovers that a mutation has occurred during the deletion of 3 consecutive nucleotides. What is its effect on amino acids?
Flashcards
Mutation Definition
Mutation Definition
A change in the nucleotide sequence of DNA.
Point Mutation
Point Mutation
A mutation affecting a single base in the DNA sequence.
Transition Mutation
Transition Mutation
A type of point mutation where a pyrimidine changes to another pyrimidine, or a purine changes to another purine.
Transversion Mutation
Transversion Mutation
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Silent Mutation
Silent Mutation
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Missense Mutation
Missense Mutation
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Nonsense Mutation
Nonsense Mutation
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Frameshift Mutation
Frameshift Mutation
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Deletion (mutation type)
Deletion (mutation type)
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Insertion (mutation type)
Insertion (mutation type)
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Study Notes
- Mutation is a change in the nucleotide sequence of DNA
- There are two types of mutations: point and frame shift
Point Mutation
- This involves single base changes, where one base is substituted for another
- There are two types of point mutations: transition and transversion
Transition Mutation
- This occurs when a pyrimidine changes to another pyrimidine, or a purine changes to another purine
Transversion Mutation
- This occurs when a purine changes to either of the two pyrimidines, or when a pyrimidine changes to either of the two purines
Effects of Point Mutation
- Silent, missense and nonsense mutations can occur
Silent Mutation
- The codon with the changed base still codes for the same amino acid
- This is due to the degeneracy of the genetic code
- The changed base is the third base of the codon
- Hemoglobin Bristol has aspartic acid at position 67, coded by codons GAU and GAC
Missense Mutation
- The codon with the changed base codes for a different amino acid
- The effect of the mistaken amino acid protein function may be acceptable, partially acceptable, or unacceptable
- Acceptable occurs when the resulting protein is not distinguishable from the normal one, like Hb Hikari
- Partially acceptable occurs when the protein function is partially affected, like Hb S
- Unacceptable occurs when the protein is non-functioning, like Hb M
Nonsense Mutation
- This occurs when the codon with the changed base becomes a termination codon
- This may lead to premature termination of translation and a short protein
Frameshift Mutation
- This is produced by deletion or insertion of nucleotides from the coding strand of a gene
Deletion
- If there is deletion of a single nucleotide, this may lead to garbled translation of the mRNA distal to the single nucleotide deletion
- Nonsense codons may result from deletion, leading to premature termination of translation
- If there is deletion of 3 nucleotides or a multiple of 3 from the coding region, this results in a protein with a missed amino acid or acids
- If there is deletion of one or two nucleotides within the termination sequence, the reading of the normal termination codons is disturbed
- This may lead to reading through a termination signal until another nonsense codon is reached
Insertion
- Give the same effects of deletions
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