Monohybrid Inheritance Flashcards
Incomplete dominace
Neither alleles dominates and the heterozygote is intermediate in phenotype betwen the two heterozygote.
Crosses involving incomplete dominance the genotype & phenotype ratios are identical.
Codominance
Both alleles are independently and eqaully expressed in the hertrozygote.
e.g ABO human blood groups
Multuple alleles
More than two alleles present in a species for one gene. One individual still posseses only two alleles.
A,B is domiant over O (recessive)
A&B are codominant
Lethal alleles
Are gene mutations that result in a gene product that is not only non-functional but affects organism survival.
Some lethal alleles are fully dominant, therefore lethal in the heterozygous.
Recessive lethal alleles are fatal only in the homozygote. The alllele mutation results in a visable heterozygote with a recongnisable phenotype.
Prue breeding
When 2 organisms with identical genotypes produce an organism with the same trait. (Both parents are homozygous for a particular trait).
Dihybrid Cross
A genetic cross between individuals with different alleles for two gene loci.
Phenotype
The physical expression of a trait.
Genotype
The genetic makeup of an organism.
Test Cross
An individual with an unknown genotype is mated with a homozygous recessive to determine their genotype.
Monohybrid Cross
A genetic cross using a single trait with two alleles
Linked genes
Genes are found on the same chromosome and are more likely to be inherited together.
Linked Genes exaplained
The observed phenotypic ratio differs from the expected phenotypic ratio. Therefore the genes involved are liken meaning it’s more likey for the genes to be inherited together.
Each parent os more likey to produce 2 different combinations of alleles in the gamates.
Corssing over can occur between linked genes and produces recomninants, ut not in the expect 9,3,3,1 ratio found with unlinked genes.
Genes that are linked are more likely to be inherited together than split.
