Difference Between Gene and Chromosome

By: | Updated: Jul-19, 2021

If you skipped out on Biology classes in high school, you may not know what a gene and a chromosome are. These terms can be confusing to someone who hasn’t studied genetics. They are important to understand, however, as you will see when we discuss the differences between a gene and a chromosome below. So let’s begin!

Genes and chromosomes are the fundamental substances that compose every living organism. Genes are also known as DNA, which is the genetic material that exists in every cell of an organism. Chromosomes are part of the genes. They contain information regarding hereditary characteristics and other biological processes. In summary, genes are the source of hereditary characteristics and chromosomes are the carrier of information.

Summary Table

Gene Chromosome
A gene is usually found within a single cell The chromosome of an organism may be present in more than one cell
A gene is usually large in size The chromosome of an organism may be smaller or even nonexistent
A gene is usually located in a specific area of the cell A chromosome does not necessarily reside in one specific location

Definitions:

Difference Between Gene and Chromosome

We are all familiar with the term gene. It is a very common word when it comes to genetics. The word ‘chromosome’ is also well known. However, what do these terms mean? Are they the same or are they different? Let’s find out what these terms mean in biology, and how they are important to our lives.

What is a Gene?

A gene is a segment of DNA that contains the genetic information for making a particular protein.

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That’s what “gene” means in Greek. In the context of genes, the word “gene” has come to mean a unit of inheritance (the inherited unit that determines a trait). The same segment of DNA can be found in different organisms and is called homologous or homologous genes. So when we say that two similar species have been found in the same place, it means that the DNA of those two species has been found in the same place or is homologous.

What is a Chromosome?

A chromosome is an organized group of genes held together by a long thread of DNA called DNA. The chromosomes are made up of molecules called nucleotides and these are arranged at specific locations on the thread. Each chromosome has thousands upon thousands of nucleotides that are organized into a number of modules called genes.

A chromosome is a long thread of DNA that is composed of many different genes. The number of genes in one chromosome varies between species, and the number of chromosomes varies according to the species. The number of chromosomes per animal can range from one to a thousand.

Although each chromosome has its own specific name, for convenience, we often refer to them by their location on the body, like “X-chromosome” or “Y-chromosome.”

What are the similarities between a Gene and a Chromosome?

There are some similarities and some differences between a gene and a chromosome.

  1. They are both related to DNA

When it comes to the genetic information in the chromosomes, DNA is central. This is because DNA is composed of genes and genes are made up of segments of DNA.

  1. They contain genetic information

A gene contains the instructions for making a particular protein and hence determines the way an organism looks and behaves. The same goes for chromosomes: they contain the genetic information that determines the structure and function of an entire organism.

  1. They contain the same type of nucleic acids

A gene is composed of nucleic acids such as DNA and RNA – which are both made up of amino acids. Similarly, the chromosomes that make up a cell contain nitrogen-containing nucleic acids called deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Both genes and chromosomes are composed of the same fundamental building blocks, structurally and functionally.

What are their differences?

There are some differences between a gene and a chromosome. They are:

  1. A gene is usually found within a single cell, while the chromosome of an organism may be present in more than one cell.

For example, the gene for ABO blood groups occurs in each and every cell of an organism. But since there is only one chromosome per animal, these genes are found within that single chromosome.

  1. A gene is usually large in size, while the chromosome of an organism may be smaller or even nonexistent!

For example, a human gene can be around 3 million nucleotides long, while a mouse’s gene can measure around 1 million nucleotides. However, just like the size of a cell, the size of a gene is determined by the amount of DNA present.

  1. A gene is usually located in a specific area of the cell, while a chromosome does not necessarily reside in one specific location.

For example, the gene for hemoglobin (a protein that transports oxygen) is found in each and every red blood cell. But since there are many genes within a single chromosome, they may also be located at different spots along its length.

  1. A gene may contain more than one unit of DNA, while a chromosome might only have one type of DNA.

For example, the gene for hemoglobin found in red blood cells is made up of two units of DNA. However, the hemoglobin proteins produced by these genes are made from only one unit of DNA. Each gene can have multiple copies of its respective unit of DNA, and each copy makes up a different subunit (or protein) in the final product.

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