Lecture 2 Learning Guide: microbial diversity, evolution and origins

what two scientists are credited with discovering microorganisms

antonie van leeuwenhoek: drawings of bacteria “animalcules” from the human mouth

robert hooke: saw a microscopical mushroom in 1965 (later identified as common bread mold) described how to make the microscope that van lee constructed 10 years later

is a virus considered a MO, why or why not

no, bcause its acellular and therefore not an organism

basic difference between prokaryotic and eukaryotic cells

prokaryotic: no nucleus or membrane bound organelles, bacteria and archaea

eukaryotic: genetical material contained within membrane bound nucleus, membrane-bound organelles, usually larger and more complex

size of human cell, protein, virus and most bacteria

human cell and bacteria need a light microscope, viruses and proteins need electron microscope

how are microorganisms named

based on genus and species. Carl linnaeus discovered the naming process and it is called binomial nomenclature.

why did some scientists have difficulty achieving the same result as pasteur with swan-neck flask.

they weren’t using the same conditions, pasteur used sugar and yeast broth, others used a hay broth. Tyndall found some microbes were heat resistant, and Cohn discovered endospores, which were not killed when the brother was heated

how the swan-neck flask experiment helped disprove the idea of spontaneous generation

proved air does not create life, but MOs inside the air are what is contaminating sterile broth. The broths were boiled, eliminating all MOs living inside (no endospores in Pasteurs version), the air was able to flow freely to the broth while the MOs were getting caught in the turns of the swan-neck. the air alone didn’t contaminate the broth, but when bottles were tilted and broth came in contact with neck, it became infected. This proved living things give rise to other living things, the idea of biogenesis. it disproved the idea that the air had a “vital force” that was generating life.

how could potato salad have been prepared safely (why did people become ill)

could have been pressure cooked instead of boiled due to endospores. Also, if they were juts boiled, they should have been re heated after, which would inactivate bacteria. she also didn’t refrigerate canned potatoes.