Allele: function, how it works, meaning


Alleles are copies of genes that influence hereditary characteristics. Each person inherits at least two alleles of a particular gene – one allele from each parent. They are also called allelomorphs.

Eye color is a good example of how alleles are expressed; Whether we will have blue or brown eyes depends on the alleles that are transmitted from our parents. Because they help determine what our bodies look like and how they function, alleles are considered an important part of the program for all who live. organisms.

Get Medical Information / Jessica Olah


Alleles play an important role in determining our inherited traits, along with DNA and genes.

Deoxyribonucleic acid (DNA) is a hereditary material that humans and other living organisms receive from each parent. Technically, it is a molecule that carries all the necessary genetic information in the cells of the body. Half of a person's DNA comes from their mother and half from their father.

Your DNA is made up of little pieces called genes. Genes act as coded instructions to control our body composition and affect our appearance. Experts estimate that humans have between 20,000 and 25,000 genes.

For most genes, one copy is inherited from the biological mother and one copy is inherited from the biological father (whom we will simply call "mother" and "father").

The version of each gene that a parent passes on to their child is called an allele. Alleles are found on chromosomes, which are the structures that contain our genes. In particular, alleles affect the functioning of cells in our body, determining traits and characteristics such as skin pigmentation, hair and eye color, height, blood type, and much more.

How does it work

The traits we inherit from our parents depend on how the alleles interact with each other. The particular way alleles pair up is known as inheritance patterns, which make up all the variations in a person's genetic traits.

Since alleles provide at least two sets of instructions for each gene, the organism must figure out which roadmap to follow, or in other words, which trait to express .

Take eye color, for example. The color of the human eye is the result of the transmission of alleles from parents to children. Different allele combinations give brown, blue, green, or hazel eyes, although the latter two are more unique than hazel or blue eyes. Here are two typical scenarios that can happen:

  • If both parents contribute the same alleles to the eye color gene, they are called homozygous . This means that the instructions provided by the alleles will be the same, so the eye color will appear. Homo- means the same thing, and -zygote refers to the zygote, which is formed when a sperm fertilizes an egg.
  • If each parent contributes a different allele for a gene, they are known to be heterozygous , which means that the instructions will not match and the body will have to move to the strongest (or dominant) allele. Hetero means something else.

This is where it can get a bit tricky. An allele can be dominant or recessive. Dominant alleles express a trait even if only one copy exists. Recessive alleles can only manifest if there are two copies, one from each parent. And you probably already realized that dominant alleles prevail over recessive ones.

For example, a trait like blue eyes is considered recessive, so it usually only appears when the alleles for blue eyes are the same in both parents. Brown eyes are considered dominant, so you only need the brown eye allele from one parent to have brown eyes .

Dominant and recessive traits

Brown eye color is a dominant trait and blue eye color is a recessive trait. Green eye color is a mixture of both and prevails over blue, but is recessive to brown.

Although two alleles form a genotype, some traits, such as eye color, have multiple alleles that affect this trait. This also includes blood type and hair color. New alleles emerge in populations through mutations, and natural selection can also play a role, giving some alleles to others.

In fact, some biologists consider alleles so important to human evolution that they define evolution as the change in allele frequencies in a population over time .


Alleles help solve almost everything that concerns a living being. But even with a solid understanding of how alleles define our traits and characteristics, genetics remains a complex area that scientists and researchers are exploring more and more every day.

It is worth mentioning that while it is possible to make fairly accurate predictions about your child's eye or hair color based on the combination of alleles, you cannot always predict with absolute certainty which traits will appear.

Note that genetic combinations also depend on "hidden" or recessive alleles that each parent may have.

Scientists originally thought that a person's eye color was determined by a simple and simple inheritance pattern. But we now know that even dominant traits, such as brown eyes, can be the result of many different combinations of alleles, and can also disappear in one generation to reappear in a later generation.

In other words, since alleles determine eye color and many other traits are complex, genetic variation can sometimes lead to unexpected results .

Get the word of drug information

While traits such as eye color or hair color are generally not associated with any major health problems , if you have any questions about how alleles can affect certain genetic diseases, you should feel comfortable discussing these issues with your doctor.

With some background information about your family tree and medical history, a healthcare professional will be able to help you determine whether a particular genetic disorder may run in your family and what it means to you and your loved ones.

Related Articles
Choosing foods to diet after a heart attack

All cardiovascular specialists agree that a healthy diet is important to reduce the risk of coronary artery disease (CHD) Read more

Different types of hysterectomies.

A hysterectomy is the surgical removal of all or part of a woman's uterus . Hysterectomy is usually done Read more

Esthetician: experience, specialties and training

An esthetician is a person who specializes in cosmetic skin care. Cosmetologists (sometimes called estheticians ) are not medical Read more

Benefits, Side Effects, Dosages, and Interactions.

CBD oil is an extract from Cannabis indica or Cannabis sativa , the same plants that produce marijuana when Read more