10

10.1 Genomics

10.2 The Human Genome Project

10.3 What the Human Genome Is Like

10.5 Gene Microarrays

10.6 Functional Genomics

10.7 Proteomics

10.4 Variation Within the Genome

Making a Restriction Map
In this exercise, you construct a restriction map by entering measured band position data from a set of electrophoresis gels. The data may be supplied by the user from real lab experiments, or the user may choose to analyze one of several data sets provided by the interactive exercise.

Cystic Fibrosis
This interactive exercise allows you to explore the way in which transport proteins influence the passage of water in and out of cells by examining the effects of a mutation that disables a particular transport protein, the one responsible for pumping chloride ions out of cells. The water transport into lung cells that results from this mutation is the direct cause of the symptoms of cystic fibrosis, a disease which scientists hope to be able to cure with gene therapy.

Genomics. The sequencing of the human genome was announced to the public on Darwin's birthday, June 26, 2000. Deciphering all of the DNA in our chromosomes was a major scientific accomplishment, as it involved sequencing some 3.2 billion bases. The genomes of many microbes have been completed, as well as solid worms, fruit flies, mice, and flowering plants. The new discipline of genomics promises to have a major impact on biology in the coming years.

1. We humans don't have as many genes as we thought.
2. Very little of the human genome is devoted to being human.
3. Who should own the human genome?
4. The secrets of your genes on a microchip.
5. Gene microarrays and personal privacy.

The Human Genome
The human genome sequence was announced on June 26, 2000, Darwin's birthday. It contains some 2.3 billion nucleotide bases, so the sequencing presented no small challenge. There were two quite unexpected results: First, we don't have nearly as many genes as we thought. Each cell contains about six feet of DNA, of which only about one inch is devoted to encoding proteins. Second, practically half the entire human genome is occupied by so-called "transposable elements," bits of DNA that hop around the genome like fleas on a dog.

Gene Therapy
While genetically modified foods remain controversial, gene-modified humans are much in demand. The search for a way to introduce "healthy" genes into people suffering from cystic fibrosis, muscular dystrophy, or other gene disorders has finally begun to pay off. Discovery of workable virus "vectors" to carry the genes has researchers pursuing gene therapy cures like hounds to a hot scent.

The Control of Patterning in Plant Root Development
With the sequencing of the Arabidopsis genome completed, scientists are now poised to learn even more about the genes that control plant development and physiological functions. For example, we are now in a position to explore one of the "deep" questions in botany--what mechanism controls the development of central pattern formation in plants? Using Arabidopsis, scientists have been identifying mutations that affect development, and then examining the genes subsequently affected by those mutations. Arabidopsis is an ideal model for studying plant pattern formation during development. Individual plants grow quickly in laboratory test tubes, growing no taller than your thumb. Its genome, now fully sequenced, aids in studying the molecular events that underlie pattern formation.

John Schiefelbein and colleagues at the University of Michigan have focused on one sharply defined aspect of plant root pattern formation in Arabidopsis, the formation of root hairs on the epidermis. The positioning of root hairs is under tight central control, and proves to be a balancing act between cell division and cell differentiation.