Module #8: Mendelian Genetics Flashcards
True Breeding
If an organism has a certain characteristic that is always passed on to it’s offspring we say that this organism bred true with respect to that characteristic
Allele
One of a pair of genes that occupies the same position on homologous chromosomes
Genotype
Two letter set that represents the alleles an organism possesses for a certain trait
Phenotype
The observable expression of an organism’s genes
Homozygous genotype
A genotype in which both alleles are identical
Heterozygous genotype
A genotype with two different alleles
Dominant allele
An allele that will determine the phenotype if just one is present in the genotype
Recessive allele
An allele that will not determine the phenotype unless the genotype is homozygous in that allele
Pedigree
A diagram that follows a particular phenotype through several generations
Monohybrid cross
A cross between two individuals concentrating on only one definable trait
Dihybrid cross
A cross between two individuals, concentrating on two definable traits
Autosomes
Chromosomes that do not determine the sex of an individual
Sex chromosomes
Chromosomes that determine the sex of an individual
Antigen
A protein that, when introduced in the blood, triggers the production of an antibody
Autosomal inheritance
Inheritance of a genetic trait not on a sex chromosome
Genetic disease carrier
A person who is heterozygous in a recessive genetic disorder
Sex linked inheritance
Inheritance of a genetic trait located on the sex chromosome
Change in chromosome structure
A situation in which a chromosome loses or gains genes during meiosis
Mutation
A radical chemical change in one or more alleles
Change in chromosome number
A situation in which abnormal cellular events in meiosis lead to either none of a particular chromosome in the gamete or more than one chromosome in the gamete
Mendel’s principals of genetics
- The traits of an organism are determined by its genes
- Each organism has two alleles that make up the genotype for a given trait
- In sexual reproduction, each parent contributes ONLY ONE of it’s alleles to it’s offspring
- In each genotype there is a dominant allele. If it exists in an organism, the phenotype is determined by that allele
