Homozygous:
* Definition: An organism is homozygous for a particular gene when it has two identical alleles (versions) of that gene.
* Example: Let's say the gene for eye color has two possible alleles: "B" for brown eyes and "b" for blue eyes. A homozygous individual could have either:
* BB: Homozygous dominant (brown eyes)
* bb: Homozygous recessive (blue eyes)
* Characteristics:
* The organism will express the trait associated with the allele it carries.
* Offspring from homozygous parents will inherit the same allele.
Heterozygous:
* Definition: An organism is heterozygous for a particular gene when it has two different alleles of that gene.
* Example: Continuing the eye color example, a heterozygous individual would have:
* Bb: One brown eye allele (B) and one blue eye allele (b).
* Characteristics:
* The organism will express the trait associated with the dominant allele. In the eye color example, the dominant allele is "B" (brown eyes), so the individual will have brown eyes even though they carry the recessive "b" allele.
* Offspring from heterozygous parents have a chance of inheriting different alleles.
Key Points:
* Dominant vs. Recessive: Dominant alleles are expressed even if only one copy is present. Recessive alleles are only expressed if two copies are present (i.e., in a homozygous recessive individual).
* Punnett Squares: Punnett squares are helpful tools for visualizing the possible combinations of alleles that offspring can inherit from their parents.
Let me know if you'd like to see an example of a Punnett square to illustrate how homozygous and heterozygous parents produce different offspring!
