Mendels laws Flashcards
Law of segregation
During gamete formation, alleles for each gene separate so that each gamete formed carries only one allele for each gene
Law of independent assortment
Genes for different traits are assorted independently during gamete formation
What is a reciprocal cross?
Pair of crosses in which the genotypes of the males and females are reversed
What is a cross test?
When an unknown genotype is crossed with a known one to determine the gametes and if it is hetero or homozygous
What is dominance?
When an allele masks the effects of another
3 forms of dominance
Dominance, incomplete dominance and codominance
Incomplete dominance
Two phenotypes fuse to form a mix of both in the F1 generation (red and white mix to make pink)
Codominance
Both dominant alleles are equally strong and expressed simultaneously (black and white chicken)
What is the dominance series?
Order of most dominant to most recessive to establish dominance between alleles
Allelic vs non-allelic gene interaction
Allelic: no dominance-recessive interaction and so new phenotypes are formed (incomplete dominance)
Non-allelic: dominance-recessive interaction so phenotype is decided by dominant gene (dominance)
Polygenic inheritance
When 2 non-allelic gene pairs are crossed it produces 4 separate phenotypes in a ratio
Epistasis
When 2 genes in a dihybrid cross are involved in the same pathway (less phenotypes observed)
What are the ratios for epistasis and polygenic inheritance?
Dominant epistasis: 12:3:1
Recessive epistasis: 9:3:4
Polygenic: 9:3:3:1
