What is the Difference between Genome and Exome?

The key difference between genome and exome lies in their composition and genetic makeup. While a genome is the entire genetic composition of an organism, exomes are merely the coding regions in the same genome.

Look at the table of differences between genome and exome below.

What is a Genome?

A genome is the total genetic information of an organism. It includes both the coding and non-coding regions of an organism, along with mitochondrial (in animals and plants) and chloroplast DNA (in plants).

The study of the genome is known as genomics. Genome information is important to study developmental, structural and functional activities of the organism. A genome consists of nucleic acid sequences, DNA in eukaryotes and RNA in viruses. The nucleic acid sequence is made up of repetitive units of nucleotides.

The first eukaryotic genome to be sequenced was that of the yeast Saccharomyces cerevisiae in 1996. It was found to be made up of more than 12 million base pairs packaged in 16 chromosomes. In 2003, the human genome was sequenced after the beginning of the human genome project in 1990.

What is an Exome?

A genome is composed of coding and non-coding regions. The coding regions are known as exons and the non-coding regions are known as introns. All the exons combined in a genome are known as exomes.

The exomes comprise 1% of the total genome. It is important to study the exomes because the majority of mutations occur in the coding regions. Therefore, sequencing and analysing only the exomes is an easier process.

The non-coding regions from the genome have to be spliced so that the coding regions can join together and translate into a functional mRNA.

Genome vs Exome

Genome

Exome

Description

The total genetic material of an organism is referred to as its genome.

The coding region of a genome is referred to as the exome.

Composition

It comprises coding and non-coding regions along with mitochondrial and chloroplast DNA.

It includes only the coding regions in a genome.

Size

It is the total (100%) genetic composition of an organism.

It comprises only 1% of the total genome in an organism.

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Frequently Asked Questions

How much of the genome is the exome?

The exome comprises about 1% of the entire genome.

What is exome and genome sequencing?

The sequencing of the entire genome is referred to as whole genome sequencing (WGS). On the other hand, sequencing of only the coding regions (exome) is referred to as whole exome sequencing.

What is the difference between exome and transcriptome?

Exome is the total coding region of a genome, whereas transcriptome is the collection of transcribed functional mRNAs.

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