Mendelian genetics, alleles, linkage, molecular mutations, mobile elements, HGT.
Classical And Molecular Genetics
Gene
Unit of heredity: a locus on chromosome whose variants (alleles) affect phenotype. Molecular definition: DNA segment encoding a functional…
Allele
Alternative sequence variant of a gene at a given locus. Diploid organism has two alleles per autosomal locus; may be homozygous…
Mendel's laws
Segregation: alleles separate in gamete formation (one per gamete). Independent assortment: alleles of different genes segregate…
Genetic linkage
Co-segregation of loci on the same chromosome at higher-than-Mendelian frequencies. Recombination frequency (cM, Morgan unit) measures…
Mutation
Heritable change in DNA sequence. Point (substitution, insertion, deletion), structural (inversion, translocation, CNV), or aneuploidy.…
Point mutation
Single-nucleotide change: missense (AA change), nonsense (stop codon), silent (synonymous), or frameshift (indel not-divisible-by-3 in…
Transposable element (transposon)
Mobile DNA sequence that moves within genome via DNA (cut-and-paste, Tc1/mariner) or RNA (copy-and-paste, retroelement) intermediates. ~50%…
Horizontal gene transfer (HGT)
Acquisition of genetic material between non-parent-offspring organisms (conjugation, transformation, transduction in prokaryotes;…
Chromosomal aberration
Structural (deletion, duplication, inversion, translocation) or numerical (aneuploidy, polyploidy). Down syndrome (trisomy 21),…
Gene conversion
Non-reciprocal transfer of sequence during recombination, converting one allele to another. Drives concerted evolution of gene families…