AP BIOLOGY

Detailed explanation-1: -In the late 1940s, Barbara McClintock challenged existing concepts of what genes were capable of when she discovered that some genes could be mobile. Her studies of chromosome breakage in maize led her to discover a chromosome-breaking locus that could change its position within a chromosome.

Detailed explanation-2: -Summary. Barbara McClintock’s discovery of transposable elements in Zea mays changed the way scientists think about genetic patterns of inheritance.

Detailed explanation-3: -In the 1950s McClintock described a novel mobile element, Suppressor-Mutator (Spm), and its complex regulation. She discovered that Spm could switch back and forth between an “inactive” form and an active form-what she called “changes of phase, ” now known to be a result of methylation.

Detailed explanation-4: -Transposons were first discovered in corn (maize) in 1948 by American scientist Barbara McClintock, whose work won her the Nobel Prize for Physiology or Medicine in 1983. Since McClintock’s discovery, three basic types of transposons have been identified.

Detailed explanation-5: -In 1983, at the age of 81, she received the Nobel Prize in Physiology or Medicine for her work on “mobile genetic elements, ” that is, genetic transposition, or the ability of genes to change position on the chromosome. McClintock was the first woman to receive an unshared Nobel Prize in that category.