News

Beer to X-rays: a genetic history

By Matt Dulin
The Daily Cougar

This is the first in a series of stories exploring the rise of genetics -- its past, present and future.

It started with beer.

Hard-nosed biotechnology scientists may not like to admit it, but their industry began 8,000 years ago when the Sumerians and Babylonians toyed with yeast to ferment the worldis first beer.

But then again, biotechnology has certainly come a long way since 6000 B.C.

Modern genetics was born much more recently, in the 1860s, with a series of discoveries made by Gregor Mendel. Mendel performed breeding experiments with flowers. He probably wasnit the first to do so, but he was the first to use statistics when tabulating the data he collected.

He gradually took note of certain recurring traits in each generation. One pattern, such as the ratio of red flowers to white flowers being 1 to 3, suggested to Mendel that a basic law of heredity was being obeyed.

To explain the phenomena, Mendel devised a pseudo-mathematical model of how traits are passed to each generation. He postulated that each generation provided one out of two possible "factors" to combine with another "factor" to form the new generationis traits. Modern science now identifies these factors as genes. Therefore, scientists later concluded, traits are encoded in genetic instructions.

Unfortunately, Mendelis findings werenit discovered by the scientific community at large until around 1900, and even then they werenit fully understood.

At the dawn of the 20th century, researchers were on the hunt to find where exactly in a cell such genetic information is stored. Chromosomes were identified early on as a possibility, as researchers had seen that the chromosomes of a dividing cell were duplicated, with a copy sent to each of the two new cells.

Herman Muller proved this condition in 1927 when, in a series of experiments, he beamed X-rays at cells. He noted the mutation of the chromosomes after exposure to the radiation, suggesting genes could be altered.

Once that question was settled, scientists went on a 20-year quest to find the chemical nature of genes and how exactly they could change.

First, in 1944, a team of scientists -- Oswald Avery, Colin MacLeod, and Maclyn McCarty -- found that genetic information was stored in something called deoxyribonucleic acid. They manipulated the chemical in bacterium strains, causing a harmless strain to become deadly.

The climax of the efforts to unravel the nature of genetics came in 1953 when American biologist James Watson and British physicist Francis Crick unveiled the double-helix structure of DNA and the role of the base chemical compounds that make up the strands. The model also explained another question being pondered by early geneticists -- how does DNA divide?

These 20th-century discoveries opened up the arena to exponential advances in scientistsi understanding of how life works on the smallest scale.

Next: Looking at how genetic research has affected our modern way of life.

 Send comments to dcnews@mail.uh.edu