Unit 1: Microscopy Flashcards
used simple microscope in 17th century with single lens and was similar to a magnifying glass.
Antoni Van Leeuwenhoek
built microscopes, which
have multiple lenses.
Robert Hooke
credited with making
the 1st compound microscope around 1600.
Zaccharias Janssen
developed a better
microscope in 1830
Joseph Jackson Lister
refers to the use of any kind of microscope that uses visible light to observe specimens
Light Microscopy
Light Microscopy
- uses visible light as its source of
illumination - Specimens appears against a
bright background.
- Dark objects are visible against a bright bg; stained
- Light objects are visible against dark bg; unstained
Compound Light Microscopy (LM)
1. Brightfield Microscopy
2. Darkfield Microscopy
Light Microscopy
permits detailed examination of internal structures in living microorganisms.
Phase-contrast Microscopy
Light Microscopy
provides a colored, 3D
image of the object being observed.
Differential Interference Contrast (DIC) Microscopy
Light Microscopy
takes advantage of fluorescence, the ability of substances to absorb short wavelengths of light and give off light at a longer
Fluorescence Microscopy
Light Microscopy
uses lasers and special optics for “optical sectioning” of fluorescently-stained specimens.
Confocal Microscopy
▪ Focus a beam of electrons through a specimen (TEM) or
onto its surface (SEM) instead of light is used. ▪ Electromagnet instead of glass lenses, control focus, illumination, and magnification
Electron Microscopy
▪ Focus a beam of electrons through a specimen (TEM) or
onto its surface (SEM) instead of light is used. ▪ Electromagnet instead of glass lenses, control focus, illumination, and magnification
Electron Microscopy
Electron Microscopy
provides for detailed study of the internal
ultrastructure in thin section of cells.
Transmission Electron Microscope
to study the surface
features of cells and viruses.
Scanning Electron Microscope
▪ Have been developed since early 1980s, used various kinds of probes to examine the
surface of the specimen at very close range.
✓ Without modifying the
specimen or damage it.
✓ To map atomic and molecularshapes
✓ To characterize magnetic and
chemical properties
✓ To determine temperature variation inside cell
SCANNED-PROBED MICROSCOPY
Scanned-probed Microscopy
- uses a thin metal tungsten
probe - Provides very detailed views of
molecules inside cells
Scanning Tunneling Microscopy
(STM)
Scanned-Probed Microscopy
- metal-anddiamond probe is gently forced down onto specimen.
- Its movement is recorded and a 3D image is produced.
Atomic Force Microscopy (AFM)
coloring the microorganisms with a dye that
emphasizes certain structures.
staining
thin film of material containing the
microorganisms is spread over the surface of the slide.
smear
Stains are salts composed of positive and a negative ion, one of which is colored and is known as the
chromophore
positive ion; which includes crystal violet,
methylene blue, malachite green and safranin.
basic stains
negative ion; which includes Picric acid,
eosin and nigrosin are common acidic stains (good for capsules)
acidic stains
staining techniques
It is an aqueous or alcohol solution
of a single basic dye.
simple staining
used to improved
bonding between the stain and the
specimen
mordant
staining techniques
React differently with different kinds of bacteria and can be used to distinguish among them
differential staining
developed in 1884 by** Hans Christian Graham**.
▪ Classify bacteria into 2 large
groups.
✓ Gram-positive & gram-negative
Gram stain
staining techniques
Cells that retain a basic stain in the
presence of acidalcohol are called
acid-fast.
acid fast staining
staining techniques
Used to color and isolate
specific parts of microorganisms
such as endospores and flagella
and to reveal the presence of
capsule.
special stains
