Barbara McClintock

1902 –1992

Barbara McClintock was a geneticist who led the field in the study of chromosomes – the packages of DNA in the nucleus of cells – and how they affect the behaviour of the cell. She was awarded a Nobel Prize in 1983 for her work.

Why do some ears of maize have different coloured kernels? Barbara McClintock showed that traits such as colour can be linked to particular chromosomes, and so as chromosomes are inherited from generation to generation, so too are the colours. But perhaps her biggest breakthrough was discovering a process that results in ears of maize that are speckled with different colours. This happens when genes responsible for colour ‘jump’ from one chromosome to another.

McClintock thought that these jumping genes were an important part of evolution, but other geneticists assumed that they were found only in maize. Over the next twenty years research built up showing that jumping genes are found in, first, bacteria, then almost all cells with DNA – proving McClintock right. Now this subject is a hot topic in biology: jumping genes help bacteria to develop resistance to antibiotics, may produce new traits in plants and animals and may cause diseases such as muscular dystrophy and cancer.

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