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31 Cards in this Set
- Front
- Back
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4 most important things to remember about cell theory:
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1. all living things are made of cells
2. all cells come from other cells 3. cells are the basic units of function/structure 4. all cells contain DNA |
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what are the 2 main cells types? what are the 3 main differences between these types & explain
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Prokaryotes & Eukaryotes--
1. Eus have nucleus, Pros dont 2. Pros DNA not enclosed--have nucleoid, plasmid (antibiotic resistance, etc), Eus have enclosed DNA 3. Eus have membrane-bound organelles, pros don't |
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light microscopes LMs do what? resolving power is what limited by what?
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refract (bend) visible light passing through an image. 2 micrometers, limited by visible light
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Resolving power--define. what is it determined by?
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measure of clarity of an image. determined by min distance 2 points must be to be distinguished
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what techniques are used to improve contrast between structures for LMs? TEMs?
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staining specimens through darkfield/phase-contrast microscopy w/ LMs, staining w/ heavy metals for TEMs
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can organelles be seen w/ a LM & define them?
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no, sub-cellular structures
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what did Robby Hooke do & when?
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1665, discovered cells in cork
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describe the electron microscope EM. how does its resolving power compare to that of a LM? when was it invented?
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invented 1950, focuses beam of electrons through specimen. resolution of .2 nanometers nms, 1000X greater than a LM
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describe the transmission electron microscope TEM:
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a beam of electrons is passed through specimen & electromagnets (acting as lenses) focus & magnify the image.
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describe the scanning electron microscope SEM:
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an electron beam scans the surface of a specimen coated with a thin gold film, exciting electrons and focusing them on a screen. makes 3-D image!
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define cytology
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the study of the microscopic appearance of cells
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describe cell fractionation
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a technique that separates major organelles of a cell so their functions can be studied. cells are homogenized by ultrasound then separated by differential centrifugation.
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what can ultracentrifuges do?
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spin up to 80,000rpm
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how does cell fractionation allow us to study the functions of organelles?
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each cellular fraction contains a large quantity of the same cellular components, thus permitting the isolated study of their metabolic functions.
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prokaryotic cells are found in which kingdom?
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are bacteria kingdom Monera, no nucleus
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what is in a nucleoid?
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bacteria DNA
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eukaryotic cells are found in
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protists, plants, fungi, animals
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define cytosol
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semifluid medium where organelles are suspended
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define cytoplasm
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entire region between nucleus, membrane enclosing cell
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bacterial cells are how big?
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1-10 micrometers in diameter
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eukaryotic cells are how big?
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10-100 micrometers in diameter
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what is the plasma membrane's function?
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it must provide sufficient surface area for exchange of oxygen, nutrients, and wastes relative to the volume of the cell
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cell membranes are made of what?
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a bilayer of phospholipid molecules/diverse proteins
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membranes compartmentalize the eukaryotic cell to serve what purpose?
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to provide environments for specific metabolic functions/participation in metabolism through membrane-bound enzymes
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define nuclear lamina
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layer of protein filaments that helps maintain the shape of the nucleus
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define magnification
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the ratio of an object's image to its real size
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what is the smallest thing a LM can see?
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small bacterium
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why do EMs have better resolution than LMs? how is resolution related to wavelength used?
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EMs have better resolution than LMs because they use a wavelength shorter than visible light because resolution is inversely related to wavelength used
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what are TEMs used to study?
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the internal ultrastructure of cells
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what are SEMs used to study? how do SEMs generate seemingly 3-D images?
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SEMs study surface structures of cells, 3-D effect from the great 'depth of field'
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LM vs EM: what are the pros/cons of each?
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LMs don't have a high resolution but they can be used to study live cells
EMs have a higher resolution thus can be used to study organelles but they can only be used on dead cells |
