Gene Mutations and Transposable Elements Flashcards
A heritable change in the nucleotide sequence of DNA
Mutation
How examining a mutant phenotype can reveal aspects of the normal function of the product of the wild-type allele
Genetic Analysis
Relatively small alterations that affect a single gene or locus
Gene Mutations
Large-scale alterations that affect chromosome number or chromosome structure
Chromosome Mutations
Mutations that occur in somatic cells
Somatic Mutations
Mutations that occur in gametes or gamete precursors and are transmitted to the next generation of offspring
Germ-Line Mutations
The alteration of a single nucleotide
Base Substitution (Point Mutation)
A mutation that alters the translation reading frame in coding regions
Frameshift Mutations
A mutation that does not alter the translation reading frame in coding regions
In-frame Mutations
A category of base substitution in which a pyrimidine is changes to a pyrimidine or a purine is changed to a purine
Transition
A category of base substitution in which a purine is changed to a pyrimidine or a pyrimidine is changed to a purine
Transversion
In many organisms, transitions are more common than transversions
Ts:Tv Bias
When the amino acid produced by the codon is changed
Missense Mutation (Nonsynonymous Mutation)
When a codon is changed to a stop codon
Nonsense Mutation
When there is a mutation, but the amino acid does not change, occur at degenerate codons
Silent Mutation (Synonymous Mutation)
A type of missense mutation in which the chemical properties of the mutant amino acid are similar to the original amino acid, in the same functional group. They often, but not always, have no effect on protein function
Conservative Mutation
A type of missense mutation in which the chemical properties of the mutant amino acid are different from the original amino acid, in a different functional group. They often, but not always, have an effect on protein function
Nonconservative Mutation
A type of dynamic mutation that involves three nucleotides. The number of copies of the repat often correlates with the severity and/or age of onset of the disorder
Expanding Nucleotide Repeats
When a genetic disease becomes more severe with each generation, often shown in disorders caused by expanding nucleotide repeats
Anticipation
Mutations that result in reduced or abolished activity of the gene product
Loss-of-Function Mutations
A type of LOF mutation that completely blocks the function of a gene product
Null (Amorphic) Mutation
A type of LOF mutation that results in weak, but detectable activity of gene product
Hypomorphic Mutation
Mutations that enhance an activity or confer a new activity or location of an activity, usually have dominant inheritance
Gain-of-Function Mutations
A type of GOF mutation that generates more gene product or the same amount of a more efficient gene product
Hypermorphic Mutation
A type of GOF mutation that generates gene product with a new function or that is expressed at an inappropriate time or place
Neomorphic Mutation
A mutation in which the wild-type allele is changed to a different allele
Forward Mutation
A mutation in which the mutant allele changes back into the wild type
Reverse Mutation
A general term for any genetic (DNA) unit that can reinsert elsewhere in the genome, generally 100-20000 bp long, occur in prokaryotes and eukaryotes
Transposable Elements
A class of TE in which TEs move around a genome and increase their copy number
Replicative TEs (Class I, Retrotransposons)
A class of TE is which TEs move around a genome but they don’t increase their copy number
Nonreplicative TEs (Class II, DNA Transposons)
A type of Class II transposon with short inverted repeats at each end that requires transposase to move. It moves as DNA, and includes AC-DS elements (maize), Tn3 and Tn10, IS elements (E. coli), and P elements (Drosophila).
DNA Transposon
A type of Class I transposon with long terminal repeats at each end, which requires reverse transcriptase and integrase to move. It moves via an RNA intermediate transcribes from a promoter in the LTR (replicative).
LTR Retrotransposon
A type of Class I transposon with a PolyA at the 3’ end, and a 5’ end that is often truncated, which requires reverse transcriptase and endonuclease to move. It moves via an RNA intermediate that is often transcribes from a neighboring promoter (replicative). Includes LINEs and SINEs
Non-LTR retrotransposon
A general type of class II TE in eukaryotes that carry a transposase gene and all DNA sequences needed to carry out transposition. Transposase encoded by one TE can act on another TE in the same genome. Includes Activator (Ac) elements of maize
Autonomous TEs
A general type of class II TE in eukaryotes that lack a transposase gene and may lack the sequences needed to transposition. They are unable to move unless transposase is provided by an autonomous element elsewhere in the genome. Includes Dissociator (Ds) Elements of maize
Nonautonomous TEs
Viruses that have genomes composed of single-stranded RNA, carry reverse transcriptase, and infect eukaryotic cells
Retroviruses
