Expert: Florence M Rollwagen - 5/15/2009

Question
How are scientists able to piece together the process of protein synthesis and the effects of genetic controls without direct observation?

Answer
Hi Connie: Thanks for your question.

Actually, they do use direct observation.  I’m giving you the example of the lactose operon in E coli, sometimes called the lac operon.  This operon is a set of genes that gets turned on when lactose is present in the bacteria’s environment.  It induces a set of proteins that is used to allow lactose to enter the cell in large amounts, and to break down lactose (a disaccharide) into glucose and galactose (both monosaccharides).

Here’s a link and a movie: http://vcell.ndsu.edu/animations/lacOperon/index.htm

The discoverers of this operon (Jacob, Lwoff and Monot) won the Nobel Prize in 1965 for their findings.  Here is a link, so you can see how it was done.  http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mcb.section.2475

Here is a good paper that describes how these discoveries came about: http://www.mhhe.com/biosci/genbio/raven6b/graphics/raven06b/howscientiststhink/1...  You will see that everything we know in science is built upon the observations and measurements of others.

Hope this helps, write back if you have more questions.

FM Rollwagen, PhD