Questions and Answers
What is the effect of a point mutation in the non-coding region of a gene?
What is an example of a missense mutation?
What is the effect of a frameshift mutation?
What type of mutation results from the insertion or deletion of 3 nucleotides (or multiples of 3)?
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What is the term for a mutation that changes the amino acid specified to a stop codon?
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What is the term for a base substitution that is a purine to purine or pyrimidine to pyrimidine change?
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What type of mutation results from the insertion or deletion of one or more bases to the DNA sequence?
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What is the effect of a silent mutation?
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What is the primary function of the protein encoded by the CFTR gene?
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What is the effect of a nonsense mutation on the resulting protein?
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What type of mutation is the CTT deletion in the CFTR gene?
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Why is the loss of the CTT codon (phenylalanine) in the protein sequence of clinical significance?
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What type of mutation is responsible for Cystic fibrosis?
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Why was PCR technique used for the detection of the CTT deletion?
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Which of the following mutations is likely to have a variable effect on the protein function?
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What is the effect of a point mutation in a regulatory region on protein production?
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What type of mutation is the homozygous mutation in the non-coding region of the β-globin gene?
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What type of mutation is responsible for Gaucher disease?
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Which of the following is a spontaneous cause of mutations?
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What is the effect of a frameshift insertion/deletion on protein function?
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What is the purpose of PCR genetic analysis in the diagnosis of Cystic fibrosis?
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What is the result of trinucleotide repeat expansion mutation in Huntington's disease?
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What is the mechanism of DNA damage caused by X-Ray?
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What is the effect of a mutation in a non-coding region on protein production?
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What is the result of UV light exposure on DNA?
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What type of mutations are caused by exposure to mutagens?
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What is the effect of smoking on DNA?
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Where do somatic mutations occur?
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What type of transmission is responsible for inherited diseases?
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What is the primary function of proofreading by DNA Polymerase during DNA replication?
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What is the consequence of failing to repair DNA damage?
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What is the frequency of mutations during DNA replication?
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What type of mutations are due to the combined effects of vertical and horizontal transmission?
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What is the purpose of DNA repair mechanisms?
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What is the primary cause of DNA damage?
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What is the role of enzymes that catalyze repair of mismatched bases during DNA replication?
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Study Notes
Small Mutations: Single Gene Mutations
- Small mutations can occur in a single gene, resulting in a change in the nucleotide sequence
- Types of small mutations include:
- Substitutions (Point mutations): a single base (nucleotide) change
- Silent: a mutation that does not alter the amino acid specified
- Missense: a mutation that replaces one amino acid with another
- Nonsense: a mutation that changes the amino acid specified to a stop codon
- Insertions, Deletions, and Frameshift mutations: an insertion or deletion of one or more bases to the DNA sequence
- Non-frameshift: insertion or deletion of 3 nucleotides (or multiples of 3)
- Frameshift: insertion or deletion of nucleotides other than 3 or multiples of 3
- Substitutions (Point mutations): a single base (nucleotide) change
Effects of Mutations
- Mutations can occur in:
- Coding regions of a gene
- Affect the amino acid sequence of the protein
- Non-coding regions of a gene
- Affect protein binding sites, promoter sequences, splice sites, etc.
- Coding regions of a gene
- Effects of mutations on protein function:
- Frameshift insertion/deletion: usually nonfunctional; often shorter than normal
- Non-frameshift insertion/deletion: possible decrease in function; variable effects
- Point mutations: do not affect quality of protein, but may affect quantity; affect rate of transcription
- Examples of genetic disorders caused by mutations:
- Cystic fibrosis: deletion of CTT in the CFTR gene
- Sickle cell anemia: non-conservative substitution in the HBB gene
- Gaucher disease: insertion of a single DNA base prevents production of an enzyme
Mutation Identification and Repair
- Causes of mutations:
- Spontaneous mutations: DNA replication errors, tautomeric shift, DNA polymerase slippage, trinucleotide repeat expansion
- Induced mutations: exposure to mutagens such as chemicals, UV light, X-rays, and tobacco smoke
- DNA repair mechanisms:
- During DNA replication: proofreading by DNA polymerase
- After completion of replication: repair of mismatched bases and DNA damage
- Importance of DNA repair: failure of DNA repair can have serious consequences, leading to disease
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Description
This quiz covers the different types of small mutations that occur in a single gene, including substitutions, insertions, and deletions. Learn about point mutations and their effects on gene expression.