Difference Between Dominant and Recessive Traits

Have you ever wondered why one of your siblings has inherited your mom's dimples but you have not? Do you have a pimple-free face just like your grandmother, whereas your sister always worries about her oily skin? You know the genes for blue eyes are in your family and your mom has that too but you wonder why you don't have blue eyes. The reality is that varied physical features are a result of specific genes as well as their expressions. In other words, you need to learn more about dominant and recessive traits determined by your genes. Keep reading to learn more.

Dominant and Recessive Alleles

Your genes determine characteristics or traits such as skin, eye, or hair color. Each gene has two alleles – one from your mother and the other from your father. Between these two alleles, one will be dominant and the other one will be recessive. The traits of dominant alleles are more likely to be expressed, whereas recessive alleles aren't expressed generally. When a dominant allele makes pair with a recessive allele, the dominant allele takes charge and determines the traits. These traits are often visibly expressed and are called phenotypes – the genetic code working behind a trait is called the genotype.

Here's a good example to learn more about dominant and recessive traits. When it comes to eye color, the allele for brown eyes (B) is dominant, whereas the allele for blue eyes (b) is recessive. It means that if one of your parents has blue eyes and the other one has brown, you are more likely to have brown eyes. The thing is that you will have brown eyes if you receive dominant alleles from both parents. You will still have brown eyes if you receive one recessive allele (b) and one dominant allele (B). You will only have blue eyes if you receive recessive allele from both parents.

The genetic material determining the trait is the genotype, which is said to be homozygous when you have two recessive or two dominant alleles from your parents or heterozygous when you have one recessive and one dominant allele from your parents.

In most cases, the child will have brown eyes when one parent contributes the recessive allele and the other the dominant  allele, because dominant allele will override the other one. Sometimes, both parents have brown eyes but they contribute the recessive allele, and as a result, the child will have blue eyes. It is important to bear in mind though that genetic inheritance isn't always that simple – you may sometimes see people have green eyes or one brown and one blue eye.

Sex Linked Inheritance

When you want to learn more about dominant and recessive traits, it is quite important to learn more about sex linked inheritance. Here's what you need to know first:

  • Females have two X chromosomes but there is one X and one Y chromosome in men.
  • The sex chromosome X has some genes that are inherited with it.
  • The X chromosome will come from mother if it is a boy and come from either mother or father when it is a girl.

It implies that males have only one allele for X-linked genes but females have two. Any issue in these sex linked genes may cause genetic defects and lead to diseases such as haemophilia. The disease affects women only when they receive two copies of recessive alleles from each parent. Since males have one X chromosome, only one copy of the haemophilia allele is enough to cause the disease. That's the reason why haemophilia is a lot more common in males.

List of Dominant and Recessive Traits

Here's a list of some most common dominant and recessive traits.

 

Dominant Traits

Recessive Traits

Eye coloring

Brown eyes

Green, grey, blue, hazel eyes

Hair

Non-red hair, dark hair, curly hair;

Widow's peak;

Full head of hair

Light, blonde, straight hair, red hair;

Normal hairline;

Baldness

Vision

Normal vision;

Farsightedness

Night blindness, color blindness;

Nearsightedness

Facial features

Unattached earlobes;

Dimples;

Broad lips;

Freckles

Attached earlobes;

No dimples;

Thin lips;

No freckles

Appendages

Fused digits, extra digits, short digits, clubbed thumb

Normal digits

Other

Normal pigmented skin;

Immunity to poison ivy;

Normal hearing, normal speaking;

Normal blood clotting;

No PKU

Albinism;

Susceptibility to poison ivy;

Deaf mutism, congenital deafness;

Hemophilia;

PKU

 
 
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