Study Guide - Unit 4 Cells

Also called the plasma membrane selectively permeable

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Unformatted text preview: ome substances can pass across them and others cannot o Semipermeable membranes Fluid Mosaic Model Proteins are embedded in the lipid bilayer and serve as “doors” Proteins The embedded proteins embedded can move around and “float” among the lipids lipids Cells and the Microscopes The Discovery of Cells • • • • • • Robert Hooke when he looked at a thin slice of cork (type of bark) 1665 Leeuwenhoek was able to observe a variety of protists swimming around in pond-water- he named these creatures protozoa Mattias Schleiden cataloged plant cells Theodore Schwann cataloged animal cells Virchow proved cells came from other cells All of these scientists – Hooke, Leeuwenhoek, Schleiden, Schwann and Virchow all contributed to the cell theory. Using the Microscope • • • Micrometer Equal to one-millionth of a meter To see even smaller objects (bacteria and smaller) we use an electron microscope • Magnification- to enlarge the appearance of something, not its physical size • Resolution- the ability to distinguish between two objects • Electron Microscopes – specimen covered in charged ions o TEM - Transmission Electron Microscope – 2-D, Black & White o SEM - Scanning Electron Microscope – 3-D image • Scanning Probe Microscopes – 3-D use a needle the width of an atom Bacteria and Viruses Bacteria • • • • • • • • • • • • Two kingdoms: Archeabacteria & Eubacteria All bacteria are prokaryotes Most bacterial cells range in size from 1 to 5 micrometers Bacteria can be seen with light microscopes All bacteria are made of 1 cell (unicellular) Bacterial chromosomes occur in a circular shape Bacteria reproduce in a process called binary fission Flagella are the tail/propeller structures which assist in movement of the bacterium Pili are hair-like projections which assist in cell reproduction Aerobic: oxygen Anaerobic: oxygen free Three shapes of bacteria: 1. Cocci sphere 2. Bacilli rod 3. Spirilla spiral • Capsule – additional layer to cell wall; it is a sticky, gel-like layer • Antibiotic- chemicals that interfere with the life process of bacteria • • When under stress, bacteria can go dormant and form endospores until con...
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