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Heterozygous vs. Homozygous: These terms refer to genetic mutations. There are two copies of the protein codes in the genetic code. If one copy is normal and the other has the mutation, it is said to be heterozygous. If both copies have the mutation, it is said to be homozygous. For example: A/A -- homozygous. A/a -- heterozygous. a/A -- heterozygous. a/a -- homozygous.

2007-05-22 13:23:05 · answer #1 · answered by xstaticadventure 2 · 1 3

As skinc said homo is alike. A zygote is the two haploid gametes merged. Therefore it means the two gametes, each carrying the same gene or allele, joined to make that zygote homologous, ie homozygous. If they both carried blood type A then the offspring is type A.
Gametes carry one copy of each chromosome, each bearing one allele from all possible alleles in the population. This means the zygote ends up with two copies. If the gametes carry different genes like blood type A and O then the zygote is heterozygous for blood type A from an allelic pool of 3.
If these two individuals had offspring the first generation would also all be type A.
But if the AO type A individual mated with another AO type A the offspring would be 1 type A homozygous: 2 type A heterozygous:1 type O homozygous
Heterozygous traits can be hidden for long periods but not always recessive. There are three blood types, three alleles, for this locus, A, B, & O but they are not dominant to each other. The gene for O does not produce a functional cell surface protein like the other two genes. Each gene is equally expressed but protein O is not functional, literally there but not counted.
Most traits are not clearly dominant or recessive. There are cases of partial dominance, epistasis (one gene is modified by one or several other genes on different chromosomes so they assort independently), or pleiotropism (a gene product works in different ways in different parts of the body resulting in multiple phenotypic effects.)
This has led to the study of trait values.
This does not refer to mutations specifically. A mutation may have been the proximate cause of the allelic difference but is not what these terms mean. Alleles differ due to many pressures and mechanisms.

2007-05-22 14:58:25 · answer #2 · answered by gardengallivant 7 · 0 0

homo means the same in Greek and hetero means different. So a homozygote has two of the same genes for a trait eg eye colour: if you get a blue gene from your mother and a blue gene from your father you will have two blue genes and blue eyes - you are a homozygote for the blue gene. If your father gave you a brown gene and your mother gave you a blue gene you would have brown eyes (brown dominates blue) and be heterozygous for eye colour. you would be able to pass on the blue gene to your children however.

2007-05-22 13:21:48 · answer #3 · answered by Anonymous · 1 1

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