Genetics
Trait
Characteristic that is inherited; can be either dominant or recessive.
The Law of Segregation
The alleles must separate when gametes are formed.
Allele
The different forms of a gene.
Dominant Allele
If an organism is heterozygous it is the trait that is expressed. Only need 1 copy of dominant allele to show dominant trait.
Recessive Allele
If an organism is heterozygous it is the trait that is “hidden”. Need 2 copies of recessive allele to show recessive trait.
Genotype
The genetic makeup, or set of alleles, of an organism. (Ex: PP, Pp or pp)
Phenotype
The observable physical traits of an organism, which are determined by its genetic makeup.
Punnett Square
A diagram used to predict the probability of how traits could be passed from parent to offpring
Homozygous
Having two identical alleles for a given gene; homozygous dominant (RR), homozygous recessive (rr)
Heterozygous
Having two different alleles for a given gene.
The Law of Independent Assortment
In dihybrid crosses, the alleles for the two traits segregate independently of each other when gametes are formed. So when looking at a parent with two traits there are four possible combinations when gametes are formed.
Dihybrid Cross
A cross between two organisms in which two traits are being considered.
Hybrid
see heterozygous, An organism that has two different alleles for a trait
Purebred
see homozygous, An organism that always produces offspring with the same form of a trait as the parent
genetics
Scientific study of heredity
heredity
Passing of traits from parents to offspring
gametes
Sex cells, sperm and egg which are haploid
Punnet Square
a tool used to predict the probability of offspring from crossing two individuals