What is a homozygous dominant genotype?

2 Answers
Jul 21, 2018

Two dominant Alleles TT, HH, RR


In a monohybrid (single trait) cross, there are three possible genotypes.

The Genotype is the possible pair of traits from the parents represented by letters called alleles

The Phenotype is the possible trait displayed by the genotype.

Using the Alleles
T = Tall
t = short

The three possible genotypes (pairs of alleles) are:

TT = Homozygous Dominant for Tall

Tt = Heterozygous Dominant for Tall

tt= Homozygous Recessive for Short

Homo = same zygous refers to zygote

Hetero = different zygous refers to zygote

Jul 21, 2018

A homozygous dominant genotype is one in which there are two dominant alleles.


In Mendelian genetics, a trait is governed by one gene with two possible alleles; one dominant and one recessive. Genotypes are usually represented as letters, with a capital letter representing the dominant allele and the lowercase letter representing the recessive allele.

A homozygous genotype is one in which both alleles are the same, and an organism with a homozygous genotype is said to be true-breeding or purebred. A homozygous dominant genotype is one in which both alleles are dominant.

For example, in pea plants, height is governed by a single gene with two alleles, in which the tall allele #("T")# is dominant and the short allele #("t")# is recessive. A true-breeding tall pea plant would have the genotype with two dominant alleles, usually represented as #"TT"#.