Skip to content
What is genomics?

Genomics is a study of the complete genetic material of a cell (the genome), including its output (transcriptomes) and regulation (epigenomics).

Genomics is different to genetics, which is the study of a single gene, heredity, and traits. The main difference between genomics and genetics is that genetics scrutinizes the functioning and composition of the single gene or trait, whereas genomics addresses all genes and their inter relationships in order to identify their combined influence on the growth, and development of the organism. Genomics studies can also reveal differences between normal and disease states of organs and cells.

Each cell contains DNA (Deoxyribonucleic acid) which is made of a string of four nucleotides A, C, G &T, and is the basic blueprint of all living organisms. The order in which these nucleotides are placed is called DNA sequence. Within cells, DNA is converted (transcribed) into RNA (Ribonucleic acid) molecules. A small number of these RNA molecules are translated into proteins while a large number of RNA molecules help proteins to carry out cellular functions. In different organs in an individual, the DNA is the same but RNA molecules are different, because the conversion of DNA into RNA molecules is tightly controlled (regulated). Genomics methods allow us to study the entire DNA content (genomics), the entire RNA output (transcriptomics), and its regulation (epigenomics).

 

Organism

No. of protein coding Genes

Genome size in bases or base pairs

Virus

HIV

9

10 thousand

Dengue virus

10

10 thousand

Coronavirus SARS-CoV2

15

30 thousand

Bacteria

Helicobacter pylori

1600

1.6 million

Neisseria meningitidis

2450

2.2 million

Burkholderia pseudomallei

6300

7.3 million

Other  organisms

Fruit fly

14000

180 million

Rice

46000

350 million

Human

21000

3.2 billion

DNA and RNA are best described as long strands consisting of millions of nucleotides in a particular order (sequence). Genomics studies require cutting up of these strands into short fragments (200 to 700 nucleotides) or long fragments (1,000 to 100,000 nucleotides), preparing them so their sequence can be read and then ‘reading’ the sequence of millions of fragments simultaneously on instruments called sequencers. The preparation of samples is called ‘library preparation’ and ‘reading’ is called massively parallel sequencing or next generation sequencing (NGS). Sequencers that read short fragments are different from sequencers that read long fragments. Sequencers generate non-human readable data, which are analysed and interpreted computationally, this is called bioinformatics data analysis. New sequencing instruments, such as the PacBio Sequel II and the NovaSeq6000, can not only read the complete DNA or RNA content of a sample within days, they can also provide special information that can help us understand their regulation.

Genomics technologies are applicable to any industry that deals with DNA. Some known applications are: monitoring seed quality for crop breeding, sequencing genomes of all native species of plant and animals in Australia, studying the effect of soil microbial diversity on soil fertility, studying the effect of environmental changes in marine plant genomes etc.

Genomics technologies have rapidly advanced to provide information on the genome, transcriptome or epigenome of a single cell. Single cell investigations are very useful in identifying differences between different types of cells, tracking the progress of cells during various stages of development, distinguishing normal cells from disease cells and designing treatments targeted towards abnormal cells. Each of our organs is made of a large number of different types of cells and single cell investigations have identified the transcriptome and epigenome of many cell types and in some cases have identified new cell types. This kind of study is also useful to study DNA or RNA from cancer tumours to help distinguish between normal cells, pre-cancerous cells and cancer cells, design targeted therapy and monitor prognosis.

Genomics in medical practice

Genomics technologies are currently used for diagnosis and treatment and monitoring prognosis for a limited number of medical conditions:

Metagenomics and Human microbiome sequencing

Metagenomics is the genomic study of microbes in our body (or in the environment, soil and water). The human microbiome is the collection of all microbiota that reside on or within human tissues and biofluids. There is still a wide gap in our understanding of the contribution of the human microbial community to disease complexity . Thanks to advances in sequencing technology, obtaining the complete genomes of human microbiome has become very simple. The current challenge is to understand the role these microbes play in human disease.