Basic Concepts & Terminology Flashcards
Diploid
Two copies of each gene (maternal & paternal)
Haploid
One copy of each gene (gamete)
Allele
Alternative form of same gene
Gene
Section of DNA that is transcribed
Homologues
Copies related by descent
Homologous
Same gene in different species
Causes of high sequence similarity between species
- Chance (same solution to same problem)
- Convergent evolution
Analogous
Performing similar function but different evolutionary origin
β/ (or β)
Gene for β-globin
β^+/ (or β^+)
Wild type (normal) allele
β^+//β^+ (or β^+/β^+)
Diploid, same alleles (homozygote)
Homozygote
An individual having two identical alleles of a particular gene or genes
Heterozygote
An individual having two different alleles of a particular gene or genes
Genotype
Specific allele composition
Phenotype
Form that is seen
Haplotype
A group of genes in an organism that are inherited together from a single parent
β^+/β^SC
Diploid, different alleles (heterozygote)
Incomplete dominance
One allele is not completely expressed over its paired allele resulting in a third phenotype in which the expressed physical trait is a combination of the phenotypes of both alleles
Balanced polymorphism
Two different versions of a gene are maintained in a population of organisms because individuals carrying both versions are better able to survive than those who have two copies of either version alone
Codominance
Alleles of a gene pair in a heterozygote are fully expressed. This results in offspring with a phenotype that is neither dominant nor recessive
Epistasis
Gene interaction that affect the phenotype
Penetrance
The extent to which a particular gene or set of genes is expressed in the phenotypes of individuals carrying it, measured by the proportion of carriers showing the characteristic phenotype
Expressivity
Individuals with same genotype show different degrees of same phenotype
