From genes to genomes
Many modern biotechnologies are based on knowledge of gene structure and function. Researchers can now study individual genes or whole genomes.
What is a gene?
A gene is a region of DNA that carries the instructions for making a particular protein.
DNA is made up of long strands of sugar-phosphate-base nucleotides (represented by the letters G, A, T, C). The instructions are “written” in the sequence of the nucleotides, for example GATCCA carries a different instruction to GACCAT. A DNA molecule actually has two strands of these nucleotides that join together and wrap around each other to from a structure know as the double helix.
What is a genome?
A genome contains the nucleotide sequence of the DNA in an organism (including all genes and non-coding sequences). A genome is unique to an individual, unless they are an identical twin.
Genome analysis
To read the nucleotides in the genes scientists use a technique called DNA sequencing. During DNA sequencing the two DNA strands are broken apart, duplicated and the nucleotides are read.
Get information sheet: DNA sequencing
The first organism to have its genome completely sequenced was a bacteria called Haemophilus influenzae in 1995. Since then the genomes of bacteria, fungi, plants and animals have had been sequenced.
In 2001, the entire human genome was sequenced. It took almost 13 years and millions of dollars – a huge amount of effort. The scientists found that a human genome has about 35,000 genes.
A future challenge for researchers, which was laid down by the National Human Genome Research Institute in the United States, is to cut the cost of sequencing an entire genome to as little as one thousand dollars by 2014.
Barcode of life
A simpler method of analysing the genetic uniqueness of an organism – without sequencing its entire genome – is to use a DNA barcode instead. Similar to the barcodes used on products in the supermarket, a DNA barcode is unique to a particular item, in this case a type of plant or animal.
DNA barcoding can be used to identify species quickly and accurately for applications in the biotech industry, forensics or to help conservation.
Get information sheet: DNA barcoding
The Consortium for the Barcode of Life (CBOL) is creating a database that can be used to identify any species in the world from the sequence of one particular gene.
Other projects are focussing on particular species. For example, the Fish Barcode of Life project known as FISH–BOL is gathering DNA barcodes for all fish species in the world. FISH–BOL involves researchers in New Zealand at the National Institute of Water and Atmospheric research (NIWA).
Get Hotshot clip: Sequencing shark DNA
Using genes and genomes
Once genes have been isolated, they can be used in techniques such as gene cloning, genetic engineering or genetic modification. These techniques have helped biotechnologists to develop pest–resistant crops, engineer bacteria that can degrade pollutants and produce proteins for treating disease.
