Unit #9: Mendelian Genetics Flashcards
What are Mendel’s two laws of inheritance?
Law of segregation and law of independent assortment.
Define the Law of Segregation
The idea that during meiosis, chromosomes will segregate, therefore, each gamete only has one copy of each gene.
Define the Law of Independent Assortment
The idea that chromosomes will assort independently of external influences.
When did Mendel observe the 3:1 phenotypic ratio in his pea plant experiment?
In the F2 generation.
What did the 3:1 ratio that Mendel observed prove?
Heritability
What do we call Mendel’s “heritable factors” today?
Genes
What is another term that can be used similarly to independent assortment?
Ploidy reduction
For a mono/dihybrid cross to work, what does the P generation have to be?
True-breeding
What is a test cross?
When a an individual with a recessive phenotype is bred with an individual with a dominant phenotype but unknown genotype. The resulting phenotypic ration is then used to determine the genotype of the dominant individual.
Define incomplete dominance
When an individual that is heterozygous for a trait shows a blend between the dominant and recessive phenotype because the dominant allele is unable to fully mask the recessive.
Define co-dominance
When BOTH alleles are expressed (not necessarily either a dominant or recessive allele present)
Define multiple alleles
When there are more than two possible alleles for a given gene.
Define a polygenic trait
A trait that is influenced by multiple genes, producing somewhat of a gradient of phenotypes.
Define epistasis
When the phenotype of one trait is influenced by the genotype of another trait. Essentially one trait “overrides” the other.
When did Mendel observe the 9:3:3:1 phenotypic ratio?
After completing a dihybrid cross.
