Principles of genetic inheritance Flashcards
Define gene
A discrete unit of DNA which codes for a protein
Define Locus
The position of a gene on a chromosome
Define Allele
An alternative form of a gene that produces a distinguishable phenotypic effect
Define Genotype
The alleles contained in an organism’s cells
Define Phenotype
The characteristics of an organism determined by its genotype and its environment
Define Homozygous
an organism which possesses two identical alleles of the same gene
Define heterozygous
an organism which possesses two different alleles of the same gene
Define dominant allele
Allele which is always expressed in the phenotype if it is present in the genotype
Define recessive allele
Allele which is only expressed in the phenotype if the dominant allele is not present
Define codominance
when both alleles affect the phenotype of a heterozygous individual
What is the law of segregation?
Law of segregation: states that the two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes
Crossing two true-breeding parents differing in two characters produces dihybrids in the F1 generation, heterozygous for both characters
A dihybrid cross, a cross between F1 dihybrids, can determine whether two characters are transmitted to offspring as a package or independently
What is the The law of independent assortment?
Each pair of alleles segregates independently of each other pair of alleles during gamete formation
When might inheritance stray from the mendelian pattern?
When alleles are not completely dominant or recessive (incomplete dominance/codominance)
When a gene has more than two alleles
When a gene produces multiple phenotypes
Genetic variation can be caused naturally by:
Mutations are changes in the DNA. A single mutation can have a large effect, but in many cases, evolutionary change is based on the accumulation of many mutations
Gene flow is any movement of genes from one population to another and is an important source of genetic variation.
Sex can introduce new gene combinations into a population.
