GENETICS 2581 - MODULE 4

genetics, western university, module 4

Mutation

Stable genome sequence variation; not transient.

Single-nucleotide polymorphisms (SNPs)

Single base substitutions that result in a new allele.

Substitutions

Single base changes in DNA sequences, can classify into transitions and transversions.

Transitions

Substitutions where a purine changes to another purine or a pyrimidine changes to another pyrimidine.

Transversions

Substitutions where a purine changes to a pyrimidine or vice versa.

Indels

Insertions or deletions of bases in DNA sequences.

Inversions

Reversals of DNA sequences; can range from a few bases to megabases.

Translocations

Joining of two regions from different chromosomes, can be reciprocal or non-reciprocal.

Mutation rate

How frequently changes occur in genome sequences.

Gene mutation rate

How often a wild-type allele changes to a mutant allele.

Sequence mutation rate

How often stable changes occur in sequence per base pair within the genome.

Spontaneous mutations

Mutations that occur without external catalysts; include replication errors.

Tautomeric shifts

Rare forms of bases that can cause mismatches during DNA replication.

Wobble

Flexibility in base pairing that can lead to mismatches in DNA.

Strand slippage

Replication error that introduces insertions or deletions by misaligning DNA strands.

Unequal crossing over

Occurs during meiosis, introducing insertions or deletions in low-complexity regions.

Deamination

Removal of an amine group, can produce uracil from cytosine.

Depurination

Loss of a purine base, leading to an abasic site during DNA replication.

Base analogs

Molecules that mimic normal bases and cause incorporation errors during replication.

Alkylating agents

Chemicals that add alkyl groups to bases, causing mispairing errors.

Hydroxylamine

Chemicals that add hydroxyl groups to cytosine, inducing incorporation errors.

Intercalating agents

Molecules that insert themselves between bases, disrupting DNA structure.

Ionizing radiation

High energy radiation that can dislodge electrons and cause double-stranded breaks in DNA.

UV light

Non-ionizing radiation that can form covalent bonds between adjacent bases, often leading to pyrimidine dimers.

DNA repair

Mechanisms that correct and manage DNA damage and mutations.

Mismatch repair

Repair mechanism that corrects mismatches after DNA replication.

Base excision repair

Repair mechanism that fixes localized damage affecting a single base.

Nucleotide excision repair (NER)

Repairs bulky DNA damage or distortions, like pyrimidine dimers.

Transposons

Noncoding DNA that can induce DNA breaks and copy to new loci.

Type I transposons

Utilize an RNA intermediate for transposition, known as retrotransposons.

Type II transposons

DNA transposons that move via cut-and-paste or copy-and-paste mechanisms.

Selfish DNA

DNA elements that replicate themselves at the cost of the host.

Linkage disequilibrium

Genetic markers (like SNPs) that tend to segregate together in populations.

Genome-wide association studies (GWAS)

Research method used to identify SNPs linked to specific phenotypes.

Manhattan Plot

Graphical representation used in GWAS to show association strength between SNPs and phenotypes.

Phenotypic variation

Differences in physical traits among individuals due to genetic variation.

Myostatin

A protein that regulates muscle development; associated with speed in horses.

Haplotypes

Specific combinations of alleles at multiple loci that are inherited together.

Selective breeding

Breeding method aimed at enhancing specific traits within a species.

Neanderthal haplotype

Genetic variations inherited from Neanderthal ancestors affecting modern humans.”},{