Genomics

The study of genes is called genetics.

It is now overshadowed by genomics and studies all the DNA in an organism.

The structure of DNA was discovered in 1953.

The structure gave evidence that DNA is the carrier of heredity, and how the molecule replicates itself.

At that time we could only study single genes.

Today the situation is vastly different.

What is genomics?

It is the study of the genome, which is the complete set of DNA in an organism.

What is a gene?

There is no precise definition of a gene.

In general genes are thought of as sequences of DNA that contain instructions for making proteins.

Proteins are the building blocks of life.

These sequences are defined by specific patterns that signal the stop and start of each gene.

Genes may overlap sharing parts of the same DNA sequence.

Currently it is estimated that human beings have 20000 to 25000 protein coding genes.

If genes are so important, why study the whole genome?

The part of protein expressing genes is called the Exome.

This is less expensive to sequence and study, so is frequently used.

Many disease causing genetic mutations are in the exome.

However, some disease causing mutations occur in the rest of the DNA.

To study them we need to sequence the entire genome.

What functions are performed by DNA sequences outside of genes?

An important example, is Telomere.

This is a region of repetitive sequences at the end of each chromosome.

They safeguard the information from being worn away, when the cells divide and replicate their DNA.

Other non genetic sequences regulate how genes function.

Some other sequences represent ancient viruses that have become integrated into human DNA.

They are usually latent, but can become activated and cause infection.

Much more genetic material appears to perform no function at all.

Do all the genes and non genetic functional elements interact in complex ways?

Indeed they do.

That is why the study of single genes in a vacuum is often misleading.

Using big data tools, genes can be studied to detect combinations of variants, that affect health.

This requires access to many people's genome, along with associated health information,

linked to this genome.

The rearer the disease the more genomes that might be examined to find mutations and other patterns.

Why has genomics become more popular recently?

The technology to sequence a human genome didn't exist till recently.

A human genome contains about three billion characters.

With current technology it is now feasible to sequence it.

The cost of sequencing is also coming down.