Homozygous Dominant and Recessive Traits — Reading Comprehension

Imagine looking in a mirror and seeing your eye color, hair color, or even the shape of your nose. Where did these unique features come from? They are all traits, or characteristics, that you inherited from your parents. The study of how these traits are passed down is called genetics. Inside every cell of your body are tiny instructions called genes. These genes act like a blueprint, telling your body how to grow and what traits to have.

Each gene for a specific trait actually comes in two versions, called alleles. You get one allele from your mother and one from your father. These alleles work together to determine your traits. Some alleles are more powerful and are called dominant alleles. They will always show their trait if present. Other alleles are less powerful and are called recessive alleles. A recessive trait only appears if two recessive alleles are inherited.

Let's think about eye color. Brown eyes are often dominant over blue eyes. If you inherit a brown eye allele from one parent and a blue eye allele from the other, you will likely have brown eyes because brown is dominant. But what if you get the same allele from both parents? That's where homozygous traits come in. When an organism has two identical alleles for a specific trait, it's called homozygous. If both alleles are dominant, it's homozygous dominant. For example, having two brown eye alleles (BB) would make you homozygous dominant for brown eyes.

On the other hand, if both alleles are recessive, it's homozygous recessive. To have blue eyes, you must inherit two blue eye alleles (bb), meaning you are homozygous recessive for blue eyes. Because the blue eye allele is recessive, it only shows up when there isn't a dominant brown eye allele to override it. Understanding homozygous dominant and recessive traits helps us see the patterns of inheritance and why we have the unique blend of characteristics we do. These patterns were first described by Gregor Mendel, the father of modern genetics.

Interesting Fact: Some human traits, like having attached earlobes, are considered recessive traits, while unattached earlobes are dominant.

What are the tiny instructions inside cells called?

Which type of allele always shows its trait?

If an organism has two identical alleles for a trait, it is called heterozygous.

What is the study of how traits are passed down?

Why do recessive traits only appear sometimes?

What does 'homozygous dominant' mean?

If a person has one brown eye allele and one blue eye allele, why are their eyes likely brown?

If a flower has alleles 'RR' for red petals, what describes its genetic makeup for petal color?

A plant has genotype 'Tt' for height. 'T' is tall and 't' is short. What trait will the plant show?

If a child has blue eyes, what must be true about their alleles for eye color?