Unit 7 - Gene Mutation Flashcards
What is a mutation?
A change in a gene’s nucleotide base sequence that affects less than 1 percent of a population and can cause a mutant phenotype.
A polymorphism is more common and may not alter the phenotype.
What is a germline mutation?
A mutation that originates in meiosis and affects all cells of an individual.
What is a somatic mutation?
A mutation that originates in mitosis and affects a subset of cells.
What are loss-of-function mutations typically associated with?
Usually recessive.
What are altered or gain-of-function mutations typically associated with?
Dominant.
What disorders can mutations in the beta globin and collagen genes cause?
Sickle cell anemia & Thalassemia (B-globin) and Osteoarthritis (Collagen)
Do different mutations in a gene always cause the same illness?
No, it varies; nomenclature is inconsistent.
What is a spontaneous mutation?
A mutation that arises due to chemical phenomena or an error in DNA replication.
What is a spontaneous mutation rate?
It is characteristic of a gene and is more likely in repeats.
What are mutagens?
Chemicals or radiation that delete, substitute, or add bases.
How can an organism be exposed to a mutagen?
Intentionally, accidentally, or naturally.
What is a point mutation?
A mutation that alters a single DNA base.
What are the two types of point mutations?
Transition and transversion.
What is a missense mutation?
A mutation that substitutes one amino acid for another.
What is a nonsense mutation?
A mutation that substitutes a ‘stop’ codon for a codon that specifies an amino acid, shortening the protein product.
What can point mutations in splice sites do?
They can add or delete amino acids.
What happens when genetic material is added or deleted?
It may upset the reading frame or otherwise alter protein function.
What is a pseudogene?
A result when a duplicate of a gene mutates (false genes)
What can transposons do?
They may disrupt the functions of genes they jump into.
What are expanding triplet repeat mutations?
Mutations that add stretches of the same amino acid to a protein.
Why do expanding triplet repeat mutations occur?
They attract each other, which affects replication.
What are copy number variants?
DNA sequences that are repeated a different number of times in different individuals.
Do copy number variants always affect phenotype?
They may have no effect or may directly or indirectly cause disease.
What can several types of mutations affect?
A gene.
