Biology Definitions Study Guide
Autosomal
A locus on any chromosome but a sex chromosome. Not sex-linked.
Hybrid
Heterozygous usually referring to the offspring of two true-breeding (homozygous) individuals differing in the traits of interest.
Incomplete Dominance
When you mix 2 colors, you get a mix of the colors.
Mendel’s Law of Independent Assortment of Alleles
Alleles or different genes are assorted independently of one another during the formation of gametes.
Mendel’s Law of Segregation
Alleles segregate from one another during the formation of gametes.
Monohybrid Cross
Cross involving parents differing in only 1 trait
Phenotype
Affecting physical appearance
Epistasis
One gene masks the expression of a different gene for a different trait
F1 Generation
Offspring of a cross between true breeding plants, homozygous for the trait of interest.
F2 Generation
Offspring of a cross involving the F1 Generation.
Genotype
The genetic constitution of an organism with respect to a trait. For a single trait on an autosome, and individual can be homozygous for the dominant, but yellow seeded plants could have a genotype of either YY or Yy.
Recessive Trait
Opposite of dominant, it hides.
Heterozygous
Differing alleles for a trait in an individual, such as Yy.
Homologous Chromosomes
The pair of chromosomes ine a diploid individual that have the same overall genetic content. One member of each homologous pair of chromosomes is inherited from each parent.
Homozygous
Both alleles for a trait are the same in an individual. they can be homozygous dominant(YY), or homozygous recessive(yy).
Alleles
The different forms of a gene. Y and y are different alleles of the gene that determines seed color. Alleles occupy the same locus, or position, on chromosomes.
Test Cross
To find if an unknown trait is recessive or dominant. You cross or with another plant and look at the offspring.
True-breeding
Homozygous for the true-breeding trait.
Co-dominant Alleles
Two different alleles at a locus are responsible for different phenotypes, and both alleles affect the phenotype of the heterozygote.
Dominant Trait
A trait expressed preferentially over another trait.
Sex Chromosomes
Sex is based on sex chromosomes.