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40 Cards in this Set
- Front
- Back
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How do we measure microbes (unit of measurement)?
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Millimeters (mm)
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What unit of measurement does um stand for?
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um is the abbreviation for micron
1000 micrometers into 1mm 1um=10-3mm=10-6m=.000001m |
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A person with great vision can maybe see....
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.2m or fine hair
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Define
Microbiology |
study of microorganisms not seen with the unaided eye; requires microscopes and staining techniques to visualize
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Define total magnification of light microscope.
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power of the objective lens x power of the ocular lens
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What is the highest magnification possible with a compound light microscope?
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1000x (oil immersion)
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Refractive Index
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is the light bending ability of a medium
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Immersion Oil
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is used to keep light from bending; oil and glass have the same refractive index; allows resolution to .2 micron
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1000x than human eye
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.2 micron resolution
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Brightfield Illumination
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exclusively used in class
dark objects are visible against a bright background |
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Darkfield Illumination
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light objects are visible against a dark background
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Advantages of the electron microscope
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very high resolution at high magnification
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drawbacks of electron microscope
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kills specimen during prep
req. vacuum w/in chamber very expensive no direct visual observation - image on film no true color because light waves are not used |
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TEM
or Transmission Electron Microscopy |
Great color; fluorescent
see internal detail up to 100,000x .2nm resolution ultrathin sections leads to distortion |
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Two methods for preparing live specimens are?
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wet mount and hanging drop mount
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SEM or Scanning Electron Microscope
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beam of electrons scan the surface that was coated with a heavy metal; reveals surface features
up to 50,000x power external detail |
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What is an advantage of light microscopy?
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ability to view live specimens and natural colors
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Define Prokarya
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pre-nucleus
one of the domains of life includes bacteria |
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What type of cell structures fall under bacteria?
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Mitochondrion
cyanobacteria chloroplast gram-negative/positive bacteria thermotoga |
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Define Eukarya
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cells with a true nucleus
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What type of cell structures fall under eukaryotic?
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protista, algae, fungi, plantae and animalia
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What is the size of prokaryotic cell?
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.2 - 8 microns
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What is the size of a eukaryotic cell?
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10 -100 microns
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Where do the chromosome reside in a prokaryotic cell?
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in the nucleoid
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What are the two distinguishing characteristics of prokaryotes?
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1. no membrane bound nucleus or organelles
2. DNA is double helix stranded, circular and supercoiled |
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Describe the typical chromosome in a prokaryote.
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single double stranded DNa molecule
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what is a plasmid?
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are circular double stranded DNA molecules that house encodegenetic info that may be advantageous but not required by cell
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What are the multi-cellular arrangements?
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pairs
chains packets clusters |
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Diplococci or diplobacilli
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pairs of cells
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streptococci or streptobacilli
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chains of cells
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sarcinae
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packets of cells
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staphylococci
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clusters of cells
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What is glycocalyx?
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sticky polysaccharide coat external to cell wall; that protects against phagocytosis and enables cell adhesion
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What are the two types of glycocalyx coats?
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1. capsule a distinct and gelatinous layer made of polysaccharide
2. slime layer diffuse and irregular layer of polysaccharide |
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What are the four characteristics of a prokaryotes filamentous appendage?
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1. anchored in BOTH plasma membrane and cell wall
2. composed of chains of protein 3. attached to a protein hook 4. powered by a proton pump within the plasma membrane |
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What is the function of flagella?
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allows motility
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What is the function of fimbriae?
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attachment - protein receptors
Fimbriae is found in bacteria only |
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what is the function of pili?
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found in some bacteria it allows for attachment and DNA transfer (pilus)
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What type of stain is used to see Flagella?
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Leifson's Flagella Stain
-uses a mordant to thicken flagella until visible |
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Describe eukaryotic cells.
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membrane bound nucleus and organelles
larger two layered double membrane ribosome synthesis MRNA |
