Historical Content Flashcards
Anton van Leeuwenhoek (1632-1723)
-learned how to use a microscope as an apprentice to a cloth merchant
-ground lenses and made microscopes that could magnify 200x
-observed single-celled organisms, muscle fibers, bacteria, and blood flow in capillaries
-called the single-celled organisms he observed “animacules”
Robert Hooke (1635-1703)
-Wrote the book: Micrographia, which documented and illustrated microscopic samples.
-contributed the term “cell” to describe the box-like structures he saw in samples under the microscope.
Matthias Jakob Schleiden (1804-1881)
-studied plants under a microscope
-realized that all plants, and all parts of plants, are made of cells.
Theodore Schwann (1810-1882)
-realized that all animal tissues are made up of cells
-wrote the first statement of cell theory in his book, Microscopic Investigations on the Accordance in the Structure and Growth of Plants and Animals (1839)
-First statement of cell theory: All living things are made of cells.
Francesco Redi (1626-1697)
-did the first experiment that showed that Spontaneous Generation was wrong
He put raw meat in three containers. Two covered, and one uncovered. Only the uncovered jar resulted in maggots.
Louis Pasteur
Pasteur modeled the way the scientific method works while solving the problem of why French wine was being spoiled. He jfirst researched the problem by examining the spoiled wine under a microscope. Seeing tiny living things in the wine (they were bacteria), he formed the hypothesis that these organisms were the cause of the spoilage and that they were getting into the wine from the air. He then conducted an experiment. He prepared a nutrient broth and placed it in two flasks: a straight-necked flask and a flask with an s-shaped neck. The s-shaped neck would prevent things in the air from falling into the broth in the flask. Pasteur discovered that the broth in the straight-necked flask was spoiled and grew the microorganisms, while the broth in the flask with the s-shaped neck did not have any of the microorganisms and was not spoiled. These results supported
Pasteur’s hypothesis, and Pasteur concluded that the microorganisms came from the air and were not spontaneously produced in the broth. He repeated his tests under different conditions and got the same results.
Describe the importance of Francesco Redi’s and Louis Pasteur’s experiments.
Both Redi’s and Pasteur’s experiments failed to provide support for the notion of spontaneous generation, a popular idea at the
time. According to that idea, new creatures could spontaneously form from other forms of matter. This notion was supported
by the fact that maggots seemed to come out of nowhere and appear on rotting meat. Redi’s experiment showed that maggots
appear where flies lay their eggs and not just on meat that happens to be rotting. Pasteur’s experiment showed that harmful
bacteria do not spontaneously form in a food; they are in the air and lead to food spoilage if the food is in contact with the
air. As a result of these experiments, the theory of spontaneous generation was abandoned. We now understand that all living things are made cells, and cells only come from other cells; they do not form by spontaneous generation.
