Whole genome sequencingSpec A3.1.11
In short
Whole genome sequencing is finding the entire base sequence of an organism's DNA. It has become much faster and cheaper: the first human genome took about 13 years, but one can now be sequenced in about a day. It is used to research evolutionary relationships and could in future allow personalised medicine.
Whole genome sequencing means determining the complete base sequence of all the DNA of an organism. The Human Genome Project produced the first human genome sequence, completed in 2003 after about 13 years and at a cost of billions of US dollars.
Since then, automated high-throughput sequencers have given increasing speed and decreasing costs. A human genome can now be sequenced in around a day for roughly a thousand US dollars or less. This means thousands of genomes, from many individuals and species, can be compared.
| Use | What it involves |
|---|---|
| Current: research into evolutionary relationships | Comparing whole genomes of different species shows how many base differences separate them, which indicates how closely related they are and when they shared a common ancestor. |
| Current: research into variation within species | Sequencing many individuals reveals SNPs and links some of them to traits or diseases. |
| Potential future: personalised medicine | A patient's own genome could be used to predict disease risk and to choose the drugs and doses that work best for that person. |
Personalised medicine raises issues too: genome data is personal, and knowing a genetic risk can affect insurance, employment and family members.
For whole genome sequencing, the guide expects three points: speed up and cost down, evolutionary relationships as a current use, and personalised medicine as a possible future use.
Quick check
In a binomial, which part has a capital letter?
Show answer
The genus name (first part). The species name is all lowercase.
State the biological species concept.
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A species is a group of organisms that can breed and produce fertile offspring.
How many chromosomes do humans and chimpanzees have?
Show answer
Humans 46, chimpanzees 48.
What is a genome?
Show answer
All the genetic information of an organism.
Written and checked against the IB Biology SL specification · Updated October 2026