Mendelian Genetics

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.

Any chromosome that is NOT a sex chromosome.

Two different alleles at a locus are responsible for different phenotypes, and both alleles affect the phenotype of the heterozygote.

A trait expressed in the phenotype if the dominant allele is present in the genotype.

Offspring of a cross between the parental (P1) generation.

Offspring of a cross involving the F1 generation.

The genetic constitution of an organims with respect to a trait. For a single trait on an autosome, an individual can be homozygous for the dominant trait, heterozygous, or homozygous for the recessive trait. Yellow seeds are dominant, but yellow seeded plants could have a genotype of either YY or Yy.

differing alleles for a trait in an individual such as Rr.

The pair of chromosomes in a diploid individual that have the same overall genetic content. One member of each homologous pair of chromosomes inherited from each parent.

Both alleles for a trait are the same in an individual. They can be homozygous dominant (YY), or homozygous recessive (yy).

Intermediate phenotype in F1, parental phenotypes reappear in F2.

Genes that are inherited together on the same chromosome.

Alleles of different genes are assorted independently of one another during the formation of gametes.

Alleles segregate from one another during the formation of gametes.

a cross in which only one trait is being studied.

Change in the DNA sequence of a gene to some new, hertiable form.

The physical appearance of an organism with respect to a trait.

Both alleles must be of this type for the recessive allele to be expressed.

sex determination is based on sex chromosomes: X and Y

a gene coded on a sex chromosome, such as the X-linked gene for color blindness.

A cross between an individual with the dominant phenotype but of unknown genotype (homozygous or heterozygous) with a homozygous recessive individual. If the unknown is heterozygous, then approximately 50% of the offspring should display the recessive phenotype.

The location on a chromosome where a particular gene can be found.

a cross in which two traits are being studied.