module 7 lec 7 Flashcards
What can mutations in a gene’s coding sequence do?
They can alter the gene product (protein).
What is a silent mutation?
A silent mutation changes a codon, but doesn’t alter the amino acid or protein.
What is a missense mutation?
A missense mutation changes a codon, resulting in a different amino acid and potentially altering protein function.
What is a nonsense mutation?
A nonsense mutation changes a codon to a stop codon, truncating the protein.
What is a frameshift mutation
A frameshift mutation adds or deletes nucleotides, shifting the reading frame and changing the protein sequence.
Can mutations outside the gene’s coding sequence affect gene expression?
Yes, they can alter gene expression without changing the protein itself.
What are regulatory mutations?
Regulatory mutations occur in promoter or enhancer regions, affecting gene transcription
How can mutations in the promoter affect gene expression?
Mutations in the promoter can decrease or increase transcription by altering the binding of transcription factors.
What is the effect of mutations in splice sites?
Splice site mutations can lead to improper RNA splicing, producing abnormal mRNA and protein.
What happens when mutations occur in the terminator sequence?
Mutations in the terminator can affect transcription termination, leading to incomplete mRNA.
Can mutations outside the gene’s coding region affect gene function?
Yes, they can affect transcription, mRNA splicing, or translation.
How can mutations outside the coding region affect transcription?
Mutations in promoters or enhancers can reduce or block transcription.
How do mutations outside the coding region affect mRNA splicing?
Mutations in splice sites can cause improper splicing, leading to abnormal mRNA.
Can mutations outside the coding region affect translation?
Yes, mutations in ribosome binding sites or terminators can disrupt translation.
What is the typical result of mutations outside the coding region?
They are usually lethal, disrupting essential gene expression processes.
What is a nonsense-suppressing mutation?
A nonsense-suppressing mutation allows amino acid addition at a stop codon, enabling the production of a full-length polypeptide.
How does a nonsense-suppressing mutation work?
It bypasses a stop codon by introducing a new codon that allows continued translation, preventing premature termination.
What effect does a nonsense-suppressing mutation have on protein synthesis?
It can result in a full-length polypeptide despite the presence of an original stop codon.
Can nonsense-suppressing mutations compensate for other mutations?
Yes, they can compensate for nonsense mutations that would otherwise stop translation prematurely.
What is a loss-of-function mutation?
A loss-of-function mutation results in reduced or absent function of a gene product, affecting the amino acid sequence or protein amount.
Can loss-of-function mutations occur outside the coding region?
Yes, they can affect regulatory regions, impacting transcription or splicing.
Are loss-of-function mutations usually recessive or dominant?
Loss-of-function mutations are typically recessive, but can be dominant in some cases.
What is haploinsufficiency in the context of loss-of-function mutations?
Haploinsufficiency occurs when one functional copy of a gene is not enough to produce a normal phenotype, often seen in dominant mutations.
What is a dominant negative mutation?
A dominant negative mutation occurs when a mutated gene product interferes with the function of the normal allele, leading to a dominant phenotype.
What are the types of loss-of-function mutations?
The types include null (amorphic) and leaky (hypomorphic) mutations.
What is a null (amorphic) mutation?
A null mutation completely abolishes the gene’s function, producing no functional protein.
What is a leaky (hypomorphic) mutation?
A leaky mutation results in partial loss of gene function, producing reduced amounts of functional protein.
What is a gain-of-function mutation?
A gain-of-function mutation results in a protein with new or enhanced activity, often leading to a new phenotype.
Are gain-of-function mutations typically dominant or recessive?
Gain-of-function mutations are almost always dominant.
What is a hypermorphic mutation?
A hypermorphic mutation enhances the function of a protein, leading to increased activity or expression.
What is a neomorphic mutation?
A neomorphic mutation creates a new protein function or causes the protein to perform an activity in the wrong place or at the wrong time.
What is the result of a neomorphic mutation?
A neomorphic mutation can lead to a new phenotype by producing proteins with novel functions or incorrect localization.
