BIOL 207

Genotype

the entire genetic information inherited by an organism or specific allele combinations

Phenotype

any detectable manifestation (morphological, behavioural, physiological, etc.) of a specific genotype

Genomics

the study & cataloguing of entire genomes & their gene products

Transcriptomics

the study of transcriptomes and their functions (mRNA, rRNA, tRNA)

Reaction norm

the pattern of phenotypic plasticity exhibited by a genotype

Mutant

rare discontinuous variants in a population

Recessive

allele that is masked when a dominant allele is present

Morph

contrasting but recurring form/type within a single population of a species (eg. melanistic forms of larger felines)

Allele

alternative form of a gene

Genome

complete genetic material within a somatic cell, including both inactive & expressed genes, as well as genetic information from organelles

Chromosome

linear (in eukaryotes) or circular (in bacteria) piece of DNA & associated proteins

p arm

short arm of a chromosome

q arm

long arm of a chromosome

Centromere

specialized proteins located in a specific region of the DNA that allow the attachment of kinetochores

Telocentric

centromere located at the very end of the chromosome (at the telomere) on one side of the chromosome

Metacentric

centromere located in the middle of the chromosome

Acrocentric

centromere located very far towards one end of the chromosome

Submetacentric

centromere located off-center of the chromosome

Kinetochore

complex of proteins that bind the centromeres & act as a docking platform for the mitotic spindle

Trait

variant of an inherited character

Character

heritable feature that varies among individuals (eg. flower color)

Single nucleotide polymorphism (SNP)

single nucleotide variations in the genome that originated as point mutations that became fixed in the population

Nondisjunction

failure of homologous chromosomes or sister chromatids to separate & move to opposite poles during cell division

Aneuploidy

having an abnormal number of chromosomes

Monosomy

loss of a single chromosome (2n−1)

Heteroallelic

having two mutant alleles of the same gene that are different from each other

Haplosufficient

gene where one functional copy is sufficient to produce a wildtype phenotype

Haploinsufficient

gene where one functional copy is insufficient to produce a wildtype phenotype

Hemizygous

cell/organism has only one copy of a gene/locus/chromosomal region

Crossing over

exchange of DNA between non-sister chromatids during meiosis

Recombination

any natural process in a diploid cell that generates new allele or chromosomal combinations

Parthenogenesis

reproductive system in which females lay fertile eggs that remain unfertilized but develop into fully reproductive female offspring

Penetrance

proportion/percentage of individuals with a specific genotype that display the corresponding phenotype

Expressivity

degree to which a given allele influences the phenotype in an individual; intensity of a phenotype

Homoplasmy

all mtDNA copies in a cell are identical

Heteroplasmy

mixture of mutant & normal mtDNA copies in a cell

Reverse genetics

mutating a gene of your choice; either removing the entire gene or simply changing specific sequences to modify/test its functions

Primer

short RNA sequence with a free 3' end that is bound by base pairing to the template strand & elongated with DNA nucleotides during DNA replication

Lagging strand

discontinuously synthesized DNA strand that elongates moving away from the replication fork

Leading strand

continuously synthesized DNA strand that elongates moving toward the replication fork

Complementation

genotype of homozygous recessive at either gene leads to the mutated phenotype but having only an allele from both genes produces a wildtype phenotype

Synteny

Two or more genes are located on the same chromosome and are physically linked together

Map unit

in chromosome mapping, an increment of 1 percent in the frequency of crossing-over

Holandric gene

gene present only on the Y chromosome

Independent assortment

random alignment of homologous chromosomes along the metaphase plate during metaphase I of meiosis

Centromeric index

measure of the percentage of the chromosome's length that is spanned by its short arm; helps distinguish between chromosome shapes

Epistasis

type of gene interaction in which the allele of one gene masks/influences the phenotypic outcome of alleles of another gene