Genetics: Genes Tell Us About Evolution
Mitch Sogin analyses the genes of a sponge in his search for the origin of animals. In order to sequence the genes, he extracts them from the cells. We see the threads of DNA in a test tube. He compares a similar gene found in all the sequences in the animals he tested. Over time small mutations occur in all genes. The more closely related the animals are, the more similar is the code in a shared gene. He created a family tree by comparing the number of changes in the code. The sponge was at the bottom because its gene had the fewest changes.
5th - 8th Grade National Standards
Every organism has a set of blueprints or instructions for specifying its traits and for carrying out its physiology and behavior. These instructions are contained in the genes.
The genes contain a record of the way that organism evolved and evidence of the common origin of all animals. Thus “the basis of the unity among organisms can be found in the genetic code.”
All animals have some of the same genes. Only since we have been able to sequence genes can we compare the genes of different organisms. Using this evidence we are able to explain how groups of animals are related to each other thus creating a family tree with the sponges as the first animal.
7th Grade California Life Science Standards
All animals have some of the same genes. Only since we have been able to sequence DNA can we compare the genes of different organisms.