THE FOUNDATIONS: Gregor Mendel’s paper on hybridisation in pea plants was published in 1865, but no-one recognised its significance until Charles Darwin’s book ‘On The Origin of Species’ was published in 1859 and became a Victorian best- seller.

Chromosomes were seen in the cells of all kinds of organisms during the late 19 th century. Their behaviour suggested that they were the carriers of hereditary information. The 12 chromosomes of a broad bean.The 46 chromosomes of a human.

The dance of the chromosomes; how sex cells are formed.

The structure of DNA was not elucidated until the 1930s. There are 4 different bases: adenine A thymine T guanine G cytosine C THIS LOOKED TOO SIMPLE TO CARRY GENETIC INFORMATION

Chromosomes contain both DNA and protein. Most biologists thought that genes were made of protein but evidence accumulated that DNA was the genetic material. In 1953 Watson and Crick published their model of the double helix and it became clear that the base sequence formed a code.

The double helix, showing base pairing. Watson & Crick’s DNA model.

What does DNA actually look like? STRING! If we can’t even see genes, how can we read them? Join our course to find out.

APPLICATIONS Medical research DNA fingerprinting Gene tests Prenatal diagnosis Genetic modification Gene therapy Cloning Stem cells

MEDICAL RESEARCH Pedigrees show if a condition is inherited. By finding the gene we can discover the fundamental problem. This may lead to better treatment. It also tells us how living organisms work.

DNA FINGERPRINTING / PROFILING This technique is used to identify individuals and, at a different level, to identify species of animal or plant. FORENSICS TRACING EVOLUTIONARY PATHWAYS PATERNITY CASES IDENTIFYING BODIES AFTER DISASTERS

Early examples of DNA fingerprinting AB A.A rape case. Would you convict 1, 2 or 3? B.Disputed paternity. Is F1 or F2 the father?