Biology I Introduction to the Cell

There are 3 primary parts 1.All living things are made of one or more cells 2.Cells are the basic unit of structure and function in all living things 3.All cells come from other cells Cell Theory

Two hypotheses: Spontaneous generation: The hypothesis that living organisms arise from nonliving matter is called spontaneous generation. (ex: maggots are created by rotting meat) Biogenesis: The Alternative hypothesis, that the living organisms arise from preexisting life, is called biogenesis (Rudolf Virchow) Biogenesis vs. Spontaneous Generation

Francesco Redi ( )  disproved spontaneous generation  showed that maggots on decaying meat came from fly eggs Louis Pasteur ( )  If microorganisms could not get into a broth, no bacteria grew Spontaneous Generation

 English Scientist, Robert Hooke, discovered cells while looking at a thin slice of cork.  He described the cells as tiny boxes or a honeycomb  He thought that cells only existed in plants and fungi  Why call them cells? ◦ Robert Hooke believed cork cells looked like the small rooms found in a monastery. Discovery of cells

 Anton van Leeuwenhoek  Used a handmade microscope to observe pond scum & discovered single-celled organisms  He called them “animalcules”  He also observed blood cells from fish, birds, frogs, dogs, and humans  Therefore, it was known that cells are found in animals as well as plants Discovery of cells

 Do NOT have a nucleus  Do NOT have membrane-bound organelles  Most are unicellular, such as bacteria  Loose strands of DNA  Smaller and simpler than eukaryotic cells Halophiles Thermophiles Prokaryotes

 Has a nucleus, which contains DNA What does a nucleus do? Controls all of a cell’s activity  Contain membrane-bound organelles  Larger and more complex than prokaryotes  All multicellular organisms (and a few unicellular ones)  Plants and animals Eukaryotes

Tools of the Biologist 1.) Cell Cultures  A cell is able to reproduce into a group of cells.  A cell is placed in a nutrient solution so it can reproduce.  Ex: Strep Throat culture s

Tools of the Biologist 2.) Compound Light Microscope  Light passes through a specimen & 2 lenses to form an image.  Produces magnifications about ,000 X.  Specimens may be live or dead.

Tools of the Biologist 3.) Stereo/dissecting Microscope  Produces 3-D images of living or dissected specimens.  Used with larger objects where light cannot pass through

Tools of the Biologist 4.) Electron Microscope  Focus beams of electrons on specimens 1000x smaller than can be viewed with Light microscope

Tools of the Biologist A.) Transmission electron microscope (TEM)  Images of thin slices of specimens

Tools of the Biologist B.) Scanning Electron Microscope (SEM)  Produces incredible 3-D images of entire specimen.

NANOWORLD IMAGES electron microscope image of a fruit fly's compound eye.