CH 12 - Gene Mutations

Vocabulary flashcards covering types of genetic mutations, specific genetic markers, and DNA repair mechanisms based on the lecture transcript.

Deleterious Mutation

Can stop or slow production of a protein, overproduce it, or impair its function

Polymorphism

A DNA base or sequence at a certain chromosomal locus that varies in a small percentage of individuals in a population

Mutant

Refers to phenotype and describes an allele

Germline Mutation

A mutation that is in every cell in an individual because it was present in the fertilized ovum

Somatic Mutation

A genetic change in a non-sex cell that is passed to the next generation of cells but not all cells in the body

Lamin A

A gene in which mutations cause different diseases in different tissues

Allelic Diseases

Different diseases caused by different mutations in the same gene

Mutagen

An agent that causes mutation

Gonadal Mosaicism

Having two or more genetically distinct cell populations in an ovary or testis, a type of spontaneous mutation

Hot Spots

Regions where mutations are more likely to occur due to repetitive sequences

Alkylating Agents

Chemicals that remove a DNA base

Acridines

Dyes that add or remove a single DNA base

Site-Directed Mutagenesis

Faster and more precise than waiting for nature or a mutagen to produce a useful gene variant

Point Mutation

A single-base change in DNA

Transition Mutation

A point mutation that replaces a purine with a purine or a pyrimidine with a pyrimidine

Transversion

A point mutation that replaces a purine with a pyrimidine or vice versa

Missense Mutation

A single-base change (point mutation) that alters a codon so that it specifies a different amino acid

Nonsense Mutation

A point mutation that changes an amino-acid-coding codon into a stop codon, prematurely terminating synthesis of the encoded protein

Nonsense-Mediated Decay

A response that destroys mRNAs in which nonsense mutations encode shortened proteins that could have toxic effects on the cell

Splice-Site Mutation

A point mutation at a site in a gene that controls intron removal, resulting in extra or absent amino acids in the protein product.

Exon Skipping

A protein that is missing contiguous amino acids because a missense mutation creates an intron splice site

Frameshift Mutation

Adding or deleting a number of bases that is not a multiple of $3$

Deletion

A mutation that removes part of a DNA sequence or part of a chromosome

Insetion

A mutation that adds DNA bases

Tandem Duplication

A copy of a DNA sequence next to the original sequence

Pseudogene

A DNA sequence that is very similar to the sequence of a protein-encoding gene but is not translated into protein

Transposon

A jumping gene that can move and alter gene function in several ways

Expanding Repeat

A short DNA sequence that is present in a certain range of copy numbers in wild type individuals but, when expanded, causes a disease

Short Tandem Repeats (STRs)

A DNA sequence of $2$ to $10$ bases that repeats at a specific site in a genome. Used in forensics to distinguish individuals

Conditional Mutation

A genotype that is expressed only under certain environmental conditions

DNA Polymerase

Acts as the DNA damage response genes that oversees replication accuracy

Thymine Dimers

When an extra covalent bond between adjacent pyrimidines occurs and damages DNA

Photopyases

Enzymes that absorb energy from visible light anad use it ot detect and bind to pyrimidine dimers and break the extra bonds in a process known was photoreactivation

Excision Repair

Enzyme-catalyzed removal of pyrimidine dimers in DNA

Nucleotide Excision Repair

Replacement of up to $30$ nucleotides, which corrects several types of DNA damage

Base Excision Repair

Replacement of one to five contiguous DNA nucleotides, which corrects oxidative damage

Mismatch Repair

Checking DNA for misalignment of short, repeated segments

Damage Tolerance

A wrong DNA nucleotide is left in place but replication and transcription proceed