Discovering the Genome
Credit: Bill and Mark Bell
Is genome size related to the “complexity” of an organism? Would you expect humans to have larger genomes than insects?
Genome sizes can be compared based on weight. A common unit of weight for measuring a genome is the picogram (pg). One picogram is 10-12 grams—that means it would take 1,000,000,000,000 picograms to make just 1 gram (about the weight of a dollar bill)! When talking about genomes, scientists sometimes refer to the weight of a genome as its "C-value."
Who Has a Bigger Genome: a Human or a Grasshopper?
1. Go to http://www.genomesize.com/.
2. On the left, click "Search Data."
3. Under the heading "Search using genus or species name" in the field marked "Common name:" enter Human and click the search button.
4. You will see a list of species with "human" as part of the name. The one we want is "Homo sapiens" (that's us!). Click on the name to see more information.
5. Look for the line marked "C-value (pg)" and write down the number. This is the weight of your genome!
6. Go back to the search page, or click on "Search Data" on the left again.
7. This time, enter "Grasshopper" in the "Common name:" box and click the search button.
8. You will see a long list of results—there are many species of grasshopper. Click on the species Acrida conica and write down the C-value. Is this bigger or smaller than the number for the human genome?
9. How many DNA base pairs are in the human and grasshopper genomes? You can convert C-values in pg to the number of base pairs by using the conversion formula (#12 in the FAQ). An Mb is a “megabase,” which is 1 million base pairs.
Additional Resources
Genome size and organism complexity