Imagine you have two sets of instructions for building something, one from your mom and one from your dad. These instructions are called alleles, and they determine your traits.
Here's the difference between dominant and recessive alleles:
Dominant Alleles:
* Think of them as the "stronger" instruction. They are always expressed, even if you only have one copy of the dominant allele.
* Represented by capital letters. For example, "B" for brown eyes.
* If you have one dominant allele and one recessive allele, you'll express the dominant trait.
Recessive Alleles:
* Think of them as the "weaker" instruction. They are only expressed if you have two copies of the recessive allele.
* Represented by lowercase letters. For example, "b" for blue eyes.
* If you have one dominant allele and one recessive allele, you won't express the recessive trait.
Example:
* Brown eyes (B) are dominant over blue eyes (b).
* Someone with two brown eye alleles (BB) will have brown eyes.
* Someone with one brown eye allele and one blue eye allele (Bb) will also have brown eyes.
* Someone with two blue eye alleles (bb) will have blue eyes.
Key Points:
* Everyone carries two alleles for each trait, one from each parent.
* Dominant alleles "mask" the expression of recessive alleles.
* You can be a carrier for a recessive trait without expressing it.
In summary:
* Dominant alleles are always expressed, while recessive alleles are only expressed when two copies are present.
* Dominant alleles are represented by uppercase letters, while recessive alleles are represented by lowercase letters.
* Knowing the difference between dominant and recessive alleles helps us understand how traits are passed down through generations.
