Excerpt from The Complete Idiot’s Guide to College Biology: Mendel
September 24, 2010 Leave a comment
Mendel and the pea plants
Gregor Mendel used tens of thousands of pea plants to make several accurate observations about inheritance decades before scientists demonstrated any of it with modern techniques. With his plants in an abbey garden, he established two laws of inheritance that reflect directly the events of meiosis, again a discovery that predated confirmation using modern techniques. His brilliance lay in his method and his math.
Math also underlies our calculations of inheritance today, determining probabilities about who will inherit which genes. The associations between genes and the characters they give us are more complex than what Mendel derived from his pea plants. They extend beyond the concept of a single gene to multiple genes and even inheritance linked to entire chromosomes or to mitochondrial DNA.
People may have a hard time wrapping their minds around the real brilliance of Gregor Mendel, the plant-crossing monk. Some students likely walk away from their studies of Mendel and his pea plants with the impression that he got lucky with those plants. But Mendel was not only lucky. He was smart, he knew his plants, and he was a true scientist who understand how to translate the biological underpinnings of his statistical results.
He also was a monk who lived in the St. Thomas Monastery for most of his adult life, where he worked as a teacher and cultivator of plants. It was the peas that would eventually lead to his fame, although Mendel died before the fame that was his due finally came his way.
Mendel’s choice: observation, not luck
Mendel came to science through a natural inclination and a great deal of training. He always had an interest in science, studying physics and chemistry at a university, and teaching science at the school associated with the monastery. At the abbey, he followed his scientific passions with his studies of variation in pea plants.
Mendel didn’t choose these plants by accident. He knew from experience that they had critical features that made them an excellent choice for his study organism. He could self cross a plant, meaning that he could use a plant’s pollen to fertilize the same plant’s ovule. The pea plants had a set of binary traits, meaning that they were either green or yellow or had either wrinkled or smooth peas, nothing in between, no “blending.” And they had short generation times, meaning that they matured fast and he’d get his results quickly.
Also, Mendel was a mathematician who could interpret his statistical data. Mendel generated a lot of data, ultimately working with about 29,000 plants to achieve his grand opus on genetics. This opus, entitled “Experiments on Plant Hybridization,” generated almost no attention from other scientists. It remained rarely cited and of little interest for decades until resurfacing in the twentieth century, when scientists began to appreciate its genius.
Why is it a work of genius? Because with nothing in the way of molecular biology tools, with no information about genes or heredity, Mendel used 29,000 pea plants to figure out exactly how parents pass on their traits to offspring. He did it through insight into the organism he chose and his training as a mathematician and scientist. But he also did it because, as is the case with so many of the greatest scientists, he had a single-minded tenacity that led him to spend years studying in headache-inducing detail the minutiae of reproduction in 29,000 plants.
Posthumous scientific fame
Now, Mendel’s work is considered so important that we’ve named an entire portion of the study of genetics after him. We call it Mendelian genetics, the genetics of heredity from parent to offspring. Mendel is now known as the father of genetics.
In spite of scientific fame coming to him only posthumously, Mendel did have a different sort of success in his lifetime. When he died, he was Abbot of his monastery, having dedicated his life to his Augustinian order, his abbey, and, through his pea plants, to science.