A. Cell Theory
1. All organisms, both unicellular and multicellular, are make up of cells.
2. Cells are the smallest units of living matter and structural and operative units of all organisms.
3. In 1830s, Mathias Schleiden (plants) and Theodore Schwann (animals) declared organisms were made of cells.
4. Cells are up to(p) of self-reproduction; Rudolf Virchow declared cells come only from preexisting cells.
B. Cell Size
1. Cells set off in size from a frogs egg ( iodin millimeter) down to one micrometer.
2. Cells need get up part of plasma membrane rangy enough to adequately exchange materials.
3. Surface-area-to-volume ratio requires that cells be small.
a. As cells get larger in volume, relative surface area actually decreases.
b. Limits how large actively metabolizing cells can become.
c. Cells needing greater surface area handling modifications such as folding, microvilli, etc.
C. Microscopy of Today
1. Bright-field microscope uses light rays center by glass lenses.
2. Transmission electron microscope (TEM) uses electrons passing by dint of specimen; focused by magnets.
3. Scanning electron microscope (SEM) uses electrons scanned crosswise metal-coated specimen.
4. Magnification is function of wavelengths; shorter wavelengths of electrons allow greater magnification.
5. Resolution is minimal distance between two objects before they are suckn as one larger object.
6. Immunofluorescence microscopy uses fluorescent antibodies to review proteins in cells.
7. Confocal microscopy uses laser beam to focus on shallow plane; forms series of optical sections.
8. Video-enhanced contrast microscopy accentuates the light and dark regions and may use a computer
to contrast regions with false colors.
9. Bright-field, phase contrast, differential enlistment and darkfield are different types of light microscopy
that improve ability to see various features.
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