Gene vs. genome: Definition, function, and impact

DNA is the genetic material or code that tells cells in the body how to replicate themselves. Within this code are genes, which are specific segments of DNA that influence certain aspects of growth and health. Collectively, scientists refer to all of an organisms genes as a genome.

Almost every cell in an organisms body contains a complete copy of its genome, packaged into chromosomes. Chromosomes are thread-like structures consisting of DNA and protein that sit inside cells.

This article will explain what DNA, genes, and genomes are. It will also look at the differences between a gene and a genome and answer some frequently asked questions.

Genes consist of DNA, which is the genetic material that tells cells how to reproduce. Strands of DNA look like a twisted ladder, which scientists call a double helix.

DNA consists of four chemicals, which are known as bases. They are:

The order of these chemical bases in a persons DNA determines how their cells grow and develop.

A gene is a segment of DNA that contains sequences of many bases, varying in size from a few hundred to 2 million. Each gene affects a specific aspect of health. For example, some genes contain instructions on how to make specific proteins.

Parents pass on their genes to their biological children. As a result, each person has two copies of each human gene one from each parent. In total, the human body has between 20,000 and 25,000 genes.

The word genome refers to all the genetic material in an organism. The human genome consists of around 3 billion DNA base pairs.

Almost every cell in the body contains a complete copy of the organisms genome, tightly packaged inside its chromosomes. Chromosomes are present in the nucleus of every cell.

Most of the human genome is the same in all people. However, about 0.001% of the genetic material will be different from person to person. This figure is even smaller in people who are related to each other.

Below are some of the differences between genes and genomes:

Genes influence health in two main ways:

Some variations in genes directly result in health conditions. These conditions are known as genetic disorders. Genetic disorders can be:

In addition to inheriting genetic disorders from parents, people can also spontaneously get them if the gene mutates during fetal development or later in life. This can result in a person having a genetic variation that their parents do not have themselves.

Learn more about autosomal inheritance.

In other cases, genes are merely risk factors for a condition. This means they can raise or lower the risk of someone getting a disease but do not directly cause it.

For example, some people carry genes that raise the risk of certain cancers, diabetes, or heart disease. Doctors call this a nonmodifiable risk factor because a person cannot change their genes.

However, having genes that raise the risk of a condition does not guarantee that a person will get it. Different genes, and different combinations of genes, pose different levels of risk. A persons environment, diet, and lifestyle also influence the risk.

Working on modifiable risk factors, which are things a person can control, can help offset the elevated risk of developing a condition.

Other terms doctors use when talking about genes include:

A gene is a specific segment of DNA that tells cells how to function. A genome is the entirety of the genetic material inside an organism. The human genome consists of between 20,000 and 25,000 genes.

Most of the human genome is the same from person to person, but variations in genes can influence someones health, appearance, and risk of developing certain diseases. There are also some conditions that occur as a direct result of specific genetic variants, such as sickle cell disease.

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Gene vs. genome: Definition, function, and impact