"From Atoms to Traits" Questions

1. Explain the significance of Mendel.

Though Darwin's Theory of Evolution was revolutionary, even he knew that some parts were problematic, especially the theory of blended inheritance. Gregor Mendel's discoveries in 1900 helped clarify this confusion with his pea breeding experiments. Mendel discovered that when true-breeding different types of pea plants the offspring had traits of one of the two parents. When further breeded, both forms of the trait could reappear in future generations without dilution. Thus, Mendel's experiments altered the perception of heritable variants from blendable to entities that are passed down from parents to offspring. He also discovered that though these variants are not always visible, they are always present.

2. Draw the structure of DNA and who discovered this structure.

The double-helix structure of DNA was discovered by Francis Crick and James Watson.

3. Explain each of the five examples of variations that occur to DNA and give an example of each.

1) point mutation (single base-pair change) ~ whippet dogs
2) insertion (insertion of new letters into the sequence) ~ pea plants
3) gene copy number (duplication of entire genes) ~ chimpanzees
4) duplication (error in duplication of letters) ~ pigs
5) regulatory changes (changes in the regulatory regions of a single gene that controls cell division patterns) ~ bushy teosinte and its descendent the modern cornstalk

4. What is evo-devo?

Evo-devo is a subspeciality within evolutionary biology which concentrations on researching the effects of changes in developmental genes and how they relate to evolution.

5. Make a connection between human migration and the mutation of lactose intolerance.

Only a minority of people continue to be able to produce lactase (and thus tolerate lactose) after childhood, and the ability to produce lactase was traced in Europeans to a mutation in regulatory DNA. Cultures, such as East African and Saudi Arabian populations, who herd milk-producing animals are also more likely to have the trait of lactose tolerance.  In "Journey of Man," we learned how African peoples migrated all over the world. This would explain how this trait can be traced from Europe to Saudi Arabia to East Africa.