from The American Heritage® Dictionary of the English Language, 4th Edition
- n. An organism that has the same alleles at a particular gene locus on homologous chromosomes.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A diploid individual that has equal alleles at one or more genetic loci.
from The Century Dictionary and Cyclopedia
- n. A zygote formed by the union of two gametes of the same kind or stock: opposed to heterozygote. See extract under heterozygole.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. (genetics) an organism having two identical alleles of a particular gene and so breeding true for the particular characteristic
This is where the heterozygote has a higher fitness than either homozygote.
If the mutation is question is severely deleterious, for example if homozygote embryos invariably die during development to take an extreme example, it can never be fixed.
A final, important point is that even with just those two simple mutations the process is convoluted almost to the point of incoherence.17 Even with just the sickle and C genes—with heterozygote versus homozygote advantage and with varying detrimental effects—the interplay of the mutant and normal genes is chaotic and tangled.
So, the idea is that some allele exists which confers an evolutionary benefit when present in the heterozygote stronger sperm, for example, and confers homosexuality in the homozygote.
I added it to the list on our Instructors' Blog, stated as follows:Students should be able to define dominance as a particular relationship between the effects of two alleles; dominance is said to exist when the phenotype of the heterozygote is the same as that of a homozygote for one of the alleles the 'dominant' one.
A2A2 homozygote, the lower the equilibrium frequency of A2, for a given value of
A1A1 homozygote is fitter than the A1A2 heterozygote, which in turn is fitter than the
In spite of my view that donated gametes should, if possible/necessary, be “aligned” to avoid the possibility of a homozygote child with a recessive genetic disease, the correct course for actual couples who want to have kids is to give them counseling, tell them about the risks, and then let them make their choice.
Every male ant who has even a single unfavorably mutated allele is in essence a “homozygote” for that allele.
An individual may be a homozygote with respect to one factor and a heterozygote with respect to another.