Spontaneous generation theory
1. Frogs come from muddy soil because they always appear in that environment.
2. Flies come from rotten meat because they always appear where meat is rotting.
1. Without the invention of the microscope, the cell theory would not have been possible.
2. All living things are made up of cells.
Provide evidence for or against the statement you chose.© BrainMass Inc. brainmass.com October 25, 2018, 12:44 am ad1c9bdddf
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Cell Theory, Without the invention of the microscope, the cell theory would not have been possible.
It is hard to argue against this statement. The invention of the microscope made the discovery of the cell possible. This was primarily down to the improved lens-grinding techniques pioneered by Antoni van Leeuwenhoek (1632-1723). In 1678, he reported to the Royal Society that he had observed "little animals" - These were in fact bacteria and protozoa in a number of samples. These findings were later confirmed by Robert Hooke (1635-1703).
There is no doubt that this paved the way for the ...
Cell theory and the Microscope - how they are linked in history
1. How did the theory of biogenesis lead the way for the germ theory of disease?
2. The antibiotic amphotericin B causes leaks in cells by combining with sterols in the plasma membrane. Would you expect to use amphotericin B against a bacterial infection? A fungal infection? Offer a reason why amphotericin B has severe side effects in humans.
3. In a Gram stain, one step could be omitted and still allow differentiation between gram-positive and gram-negative cells. What is that one step and how will the two categories of bacteria appear?
4. Using a good compound light microscope with a resolving power of 0.3 µm, a 10X ocular lens, and a 100X oil immersion lens, would you be able to discern two objects separated by 3 µm? 0.3 µm? 300 nm? Why would, or wouldn't, you be able to do this with the presented microscope?
5. Why can prokaryotic cells be smaller than eukaryotic cells and still carry on all of the functions of life?
6. Distinguish clearly between eukaryotic and prokaryotic cells, giving examples of each type of cell cell (be thorough and organized in your response).
7. In 1861, Louis Pasteur observed that when yeasts grow in a sugar and protein medium, completely free of air, they ferment vigorously; and for every gram of yeast that forms, 60 to 80 grams of sugar disappeared. If the experiment is carried out in the presence of air, for one gram of yeast that forms, only 4 to 10 grams of sugar are removed. The yeasts again ferment if transferred to a sugar-containing medium absent air.
When the experiment is repeated with a protein medium, the yeasts grow only in the presence of oxygen. Pasteur concluded that the yeasts can take oxygen from air, and in the absence of air, the yeasts take oxygen from sugar.
Pasteur applied quantitative methods to his studies of fermentation and was the first to report on organisms that could live and reproduce in the absence of oxygen. His conclusions were, however, incorrect. These different behaviors of yeasts are known today as the Pasteur effect.
1. Explain the three yeast behaviors based on modern concepts of microbial metabolism.
2. What was incorrect about Pasteur's conclusion?