What are two types of mutagens from the environment?
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Chemicals and radiation (UV, ionizing).
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What are two types of mutagens from the environment?
Chemicals and radiation (UV, ionizing).
Which mutations can cause a protein sequence change?
C. II and III
What is a loss-of-function mutation?
A mutation that disrupts the function of the gene product.
How do regulatory changes affect protein degradation?
Regulatory changes affect how quickly a protein is degraded.
What is the consequence of a splice acceptor site mutation in pre-mRNA splicing?
A splice acceptor site mutation can result in exon skipping.
What is the likely impact of a missense mutation with the same charge on protein function?
Potentially minor impact.
How can mutations affect an organism's fitness?
Mutations can affect an organism's fitness by altering traits that influence survival and reproduction, potentially leading to advantages, disadvantages, or neutral effects.
Are all DNA repair mechanisms perfect?
No, many repair mechanisms exist, but not all are perfect.
What happens if there are no mutations in the coding sequence?
There will be no changes.
How did the loss of odorant receptors affect the switch to herbivory according to Goldman-Huertas et al (2015)?
The loss of odorant receptors helped switch to herbivory.
How common are loss-of-function mutations compared to gain-of-function mutations?
Loss-of-function mutations are more likely than gain-of-function mutations.
What are the common sequences for splice donor and acceptor sites in pre-mRNA splicing?
The common sequence for the splice donor site is GU, and for the splice acceptor site is AG.
How can mutations affect genes and gene products?
Mutations can alter the sequence of DNA, potentially leading to changes in the mRNA and the resulting protein, which can affect the protein's function.
How do mutations impact organismal fitness?
Fitness impact varies depending on the mutation.
What could be the consequences of a mutation at the start codon?
A mutation at the start codon could affect splicing, potentially splicing out the exon entirely or not splicing at all.
What is a gain-of-function mutation?
A mutation that improves, increases, or innovates the function of the gene product.
What is the difference between LOF and GOF in terms of their effects?
LOF (Loss-of-Function) and GOF (Gain-of-Function) describe the effects on gene activity and product, not cellular or organismal phenotype.
Which statement(s) best describe the mutant allele containing a 20bp deletion?
All of the above
What type of mutation is likely to have the least impact on protein function?
Silent mutation
What type of mutation is likely to have the most severe impact on protein function?
Frameshift mutation
What is a silent/synonymous mutation?
A mutation where a codon changes but still codes for the same amino acid, e.g., AAG (Lys) -> AAA (Lys).
What can imperfect DNA repair lead to?
Imperfect DNA repair can lead to permanent changes to the DNA, i.e. mutations.
What occurs during an insertion mutation?
An insertion mutation involves the addition of one or more nucleotide base pairs into a DNA sequence.
What effect do mutations in promoters and enhancers have on gene expression?
They change the expression (when, where, how much).
What happens to the pre-mRNA sequence in Scenario 1 when the splice acceptor site is mutated?
In Scenario 1, when the splice acceptor site is mutated, the exon is skipped.
Which type of missense mutation is likely to have a moderate impact on protein function?
Missense mutation (same charge)
What is the likely impact of a missense mutation with a different charge on protein function?
Potentially significant impact.
What is a missense/nonsynonymous mutation?
A mutation where a codon changes and codes for a different amino acid, e.g., UUU (Phe) -> UCU (Ser).
What happens during a duplication mutation?
A duplication mutation occurs when a segment of DNA is copied and inserted into the genome, resulting in multiple copies of that segment.
What is the impact of mutations in introns?
Mutations in introns can have no effect, change expression if they act as enhancers/promoters, or alter splicing if they affect splice sites.
What is an example of a condition associated with Gain-of-Function mutations?
Malignant migrating partial seizures of infancy is an example of a condition associated with Gain-of-Function mutations.
What is the consequence of a splice donor site mutation in pre-mRNA splicing?
A splice donor site mutation can lead to the retention of the intron.
What are the main types of mutations?
The main types of mutations include point mutations, insertions, deletions, and chromosomal rearrangements.
What is the likely impact of a nonsense mutation on protein function?
Likely severe impact.
What is a deletion mutation?
A deletion mutation is the loss of one or more nucleotide base pairs from a DNA sequence.
How do mutations in the 5’ and 3’ UTRs affect mRNA?
They change mRNA stability and localization.
What is the likely impact of a silent mutation on protein function?
Minimal to no impact.
Between two nonsense mutations, which one is likely to have a more severe impact on the protein?
Nonsense mutation 1 (closer to the start of the gene)
What is a frameshift mutation?
A mutation caused by insertions or deletions that change the reading frame of the codons, e.g., AAG UAC UCU AAG CCA GGC UAA (Lys-Tyr-Ser-Lys-Pro-Gly) -> AAG UAC CUC UAA GCC AGG CUA A (Lys-Tyr-Leu).
Which mutation(s) can cause protein sequence change?
C. II and III
What is an inversion mutation?
An inversion mutation involves a segment of DNA being reversed end to end, effectively flipping the sequence within the genome.
What does GOF stand for and what is its significance?
GOF stands for Gain-of-Function. It is a source of novelty, but new is not always good.
What effect does the 20bp deletion have on the reading frame of the gene?
The deletion created a frameshift
What are common sources of mutations?
Common sources of mutations include errors during DNA replication, exposure to mutagens such as UV light and chemicals, and viral infections.
Why might nonsense mutation 2 be less severe than nonsense mutation 1?
Nonsense mutation 2 occurs later in the gene, so the protein is mostly made and thus may still retain some function.
Why are most mutations inconsequential?
Redundancy in the gene and protection in mutations.
What effect does a promoter mutation have on protein sequence?
A promoter mutation will affect how the gene is regulated, thus it will not change the protein sequence.
What occurs during a translocation mutation?
A translocation mutation involves segments of DNA being rearranged between different chromosomes or within the same chromosome, leading to a change in the position of the genetic material.
What are two examples of Gain-of-Function mutations?
Two examples of Gain-of-Function mutations are increased protein activity and ectopic expression.
How does the 20bp deletion affect the size of the protein encoded by the gene?
The deletion decreased the size of the protein
Which type of mutation introduces a premature stop codon in the protein sequence?
Nonsense mutation
What is the likely impact of frameshift mutations on protein function?
Likely severe impact.
What is a point mutation/substitution?
A point mutation or substitution is a type of mutation where a single nucleotide base is changed, inserted, or deleted from a sequence of DNA or RNA.
Why are loss-of-function mutations more likely than gain-of-function mutations?
Because it is easier to break something than to make something new.
What type of mutation is described by a mutant allele causing fast, abnormal cell growth due to a 20bp deletion?
GOF mutation
What happens to the pre-mRNA sequence in Scenario 2 when the splice donor site is mutated?
In Scenario 2, when the splice donor site is mutated, the intron is retained.
What type of mutation changes an amino acid to one with a different charge?
Missense mutation (different charge)
What are the phenotypic consequences of mutations?
Phenotypic consequences of mutations can range from no visible effect to significant changes in physical traits or metabolic functions, depending on the mutation's nature and location.
What is a nonsense/premature stop mutation?
A mutation where a codon changes to a stop codon, e.g., UAC (Tyr) -> UAA (stop).
