Dominant vs Recessive
The words dominant and recessive are encountered in the study of biology, particularly physical traits in the study of genetics. For every physical trait, you receive two copies of the gene, one from your father, and the other from your mother. For example, if your mother has blue eyes, and your father has brown eyes, you will have a copy of brown eyes from father and blue eyes from your mother. Now as far as eyes are concerned, brown eyes have dominant genes while blue eyes have recessive genes. A dominant gene is represented in capital whereas a recessive gene is represented in small letter. So you could have a BB, Bb, or bb versions of genes. In case of BB, you got brown copy from both father as well as mother. So in all probability you will have brown eyes. In case of Bb, you have one dominant and other recessive gene, so you still end up as having brown eyes. However, if you happen to receive bb combination, you are likely to have blue eyes as you have received recessive trait from both the parents.
Take the example of hair type. You could have either curly or straight hair which are expressed by letters C and S. If you receive two copies of curly version, you get curly hair, and if you receive two copies of straight hair, you are likely to have straight hair. But if you have a situation where you get one copy each of curly and straight hair, you get a mixture of the two which is neither curly nor straight but is wavy instead.
A gene is called dominant when it is often seen and a recessive gene is one that doesn’t appear as often or disappears completely. In the case of eye color, brown is the dominant gene while blue is recessive gene. Dominant genes are more likely to be passed down to future generations while recessive or weak genes disappear in the process, continuing to a few generations only.
The theory of genetics (Law of Segregation) was propounded by Mendel who said that every organism has two genes for each trait. These different forms of genes are called alleles. If both alleles are identical, the organism is called homozygous and if different, he is called heterozygous for that particular trait. When the two alleles are different, it is the stronger one that shows up in the organism, hiding or masking the weaker one. The gene that shows up is called dominant, while the masked one is called recessive. While the dominant gene shows up, the recessive gene is still there though masked. Recessive genes are showed up only when the organism receives recessive copies from both parents (aa).
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In brief: • Dominant and recessive are terms used for genes that are strong and weak respectively • Dominant genes show up in the form of a trait while recessive genes get hidden by dominant genes • It is only when an individual receives recessive genes from both parents that recessive gene shows up.
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