EPISODE PREVIEW
Journey from the valleys and waterfalls of Wales to the jungles of the Amazon to explore the controversy swirling around a startling new theory of evolution developed simultaneously by Alfred Russell Wallace and Charles Darwin.
© 1974, British Broadcasting Company
Read Robert Frost's poem "On a Bird Singing in its Sleep" , the first poem on THIS PAGE.
(If you enjoy this poem, try some of the other Frost poems on the same page.)
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Explore an interactive tree of life at Evogeneao.
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Handedness of Biomolecules (an explanation)
Bronowski mentions that Pasteur was fascinated by substances, such as crystals of tartrate, had left- and right-handed forms. He surmised that these properties reflected asymmetry -- handedness -- in the molecules making up these crystals.
(Many crystalline forms of substances reflect macroscopically (that is, big enough to see) the symmetry of their underlying molecules. See THIS, section A.)
He grew crystals of chemically synthesized tartrate, and found that he could separate left- and right-handed crystals under a microscope. When he made solutions of them separately, then crystallized them again, both forms maintained their asymmetry.
