The genome, or genetic material, of an organism (bacteria, virus, potato, human) is made up of DNA. Each organism has a unique DNA sequence which is composed of bases (A, T, C, and G). If you know the sequence of the bases in an organism, you have identified its unique DNA fingerprint, or pattern. Determining the order of bases is called sequencing. Whole genome sequencing is a laboratory procedure that determines the order of bases in the genome of an organism in one process.
How does whole genome sequencing work?
Scientists conduct whole genome sequencing by following these four main steps:
- DNA shearing: Scientists begin by using molecular scissors to cut the DNA, which is composed of millions of bases: A’s, C’s, T’s and G’s, into pieces that are small enough for the sequencing machine to read.
- DNA bar-coding: Scientists add small pieces of DNA tags, or bar codes, to identify which piece of sheared DNA belongs to which bacteria. This is similar to how a bar code identifies a product at a grocery store.
- Whole genome sequencing: The bar-coded DNA from multiple bacteria are combined and put in the whole genome sequencer. The sequencer identifies the A’s, C’s, T’s, and G’s, or bases, that make up each bacterial sequence. The sequencer uses the bar code to keep track of which bases belong to which bacteria.
- Data analysis: Scientists use computer analysis tools to compare bacterial sequences and identify differences. The number of differences can tell the scientists how closely related the bacteria are, and how likely it is that they are part of the same outbreak.
How it improves health care system
- With this information we can then track how specific forms of the virus are spreading locally, nationally and internationally. It makes COVID-19 the first outbreak to be tracked in near real-time on a global scale.
- This helps with controlling the virus. For example, together with PCR testing, sequencing helped reveal the emergence of the alpha variant in winter 2020. It also showed that alpha was rapidly becoming more prevalent and confirmed why, revealing that it had significant mutations associated with increased transmission. This helped inform decisions to tighten restrictions.
- Sequencing has done the same for omicron, identifying its concerning mutations and confirming how quickly it’s spreading. This underlined the need for the UK to turbocharge its booster programme.
- Genome sequencing also has a role to play in the future of healthcare and medicine. It has the potential to diagnose rare genetic disorders, inform personalised medicine, and monitor the ever-increasing threat of drug resistance.
- With COVID-19, researchers were able to monitor the outbreak only once it had started. But the creation of rapid testing and screening programmes for other new diseases, as well as the infrastructure to conduct widespread sequencing, has now begun. These will provide an early warning system to prevent the next pandemic taking us by surprise.
- For instance, in the future, surveillance programmes may be put in place to monitor wastewater to identify disease-causing microbes (known as pathogens) present in the population. Sequencing will allow researchers to identify new pathogens, allowing an early start on understanding and tracking the next outbreak before it gets out of hand.
How to structure
- Give an intro about Genome Sequencing
- Explain how it improves the Health care system – use examples
- Mention any related schemes / programmes and conclude