Molecular Evolution

Vocabulary flashcards for Molecular Evolution lecture.

Orthologous genes (orthologs)

Related genes in different species.

C-value

The total amount of DNA in the genome (per haploid set of chromosomes).

C-value paradox

The lack of relationship between the DNA content (C-value) of an organism and its coding potential.

Monocistronic mRNA

mRNA that encodes one polypeptide.

Polycistronic mRNA

mRNA that includes coding regions representing more than one gene.

Scarce (complex) mRNA

mRNA that consists of a large number of individual mRNA species, each present in very few copies per cell.

Abundance

The average number of mRNA molecules per cell.

Abundant mRNA

Consists of a small number of individual species, each present in a large number of copies per cell.

Housekeeping gene

A gene that is (theoretically) expressed in all cells because it provides basic functions needed for sustenance of all cell types.

Luxury gene

A gene encoding a specialized function (usually) synthesized in large amounts in particular cell types.

Synonymous mutation

A change in DNA sequence in a coding region that does not alter the amino acid that is encoded.

Nonsynonymous mutation

A change in DNA sequence in a coding region that alters the amino acid that is encoded.

Fixation

The process by which a new allele replaces the allele that was previously predominant in a population.

Genetic hitchhiking

The change in frequency of a genetic variant due to its linkage to a selected variant at another locus.

Linkage disequilibrium

A nonrandom association between alleles at two different loci, often as a result of linkage.

Codon bias

A higher usage of one codon in genes to encode amino acids for which there are several synonymous codons.

Introns late model

The hypothesis that the earliest genes did not contain introns, and that introns were subsequently added to some genes.

Exon shuffling

The hypothesis that genes have evolved by the recombination of various exons encoding functional protein domains.

Nonallelic genes

Two (or more) copies of the same gene that are present at different locations in the genome (contrasted with alleles, which are copies of the same gene derived from different parents and present at the same location on the homologous chromosomes).

Pseudogene

Homologous to functional genes but has no functional role, or has lost its original function.

Autopolyploidy

Polyploidization resulting from mitotic or meiotic errors within a species.

Allopolyploidy

Polyploidization resulting from hybridization between two different but reproductively compatible species.

2R hypothesis

The hypothesis that the early vertebrate genome underwent two rounds of duplication.