Lecture 3 Examination Of Microorganisms Flashcards
The technical field of using
microscopes to view
samples & objects that
cannot be seen with the
unaided eye (objects that
are not within the
resolution range of the
normal eye).
Microscopy
Generally, light is passed
from a source through a
condenser to focus it on the
sample to have maximum
brightness then it goes
through the objective lens to
magnify the image of the
sample & then to the oculars,
where the enlarged image is
viewed.
Compound Microscope
further magnifies the
object and forms a real image
Magnification: 10X
Ocular lens
Initially magnifies object-form real
image
objective lenses
Magnifications of objective lenses?
• Scanning objective –4x
• Low Power Objective (LPO) –10x
• High Power Objective (HPO)–40x
• Oil immersion objective (OIO) – 100x
Product of the magnifying powers of the objective
and ocular lenses
Total Magnification of the microscope:
Total magnification of objective lenses
• LPO –10 x 10 = 100 times
•HPO–40 x 10 = 400 times
•OIO – 100 x 10 = 1000 times
Is the product of the magnifying
powers of the ocular (eyepiece) and the objective
lens.
Magnification
The shortest distance between two
points on a specimen that can still be distinguished
by observer, camera or lens of the microscope.
Resolution
Is a
technique used to increase the
resolving power of a microscope.
oil immersion
can be increased without
limit but not resolution because it is
dictated by the physical properties of
light (i.e. wavelength)
Magnification
a specimen viewed
through a microscope can be
increased by changing the objective
lens to a higher magnification (eg.
from LPO to HPO).
resolution
affords/gives
higher resolution
Shorter wavelength light
is the measure of its ability
to gather light and to
resolve fine specimen
detail while working at a
fixed object (or specimen)
distance.
numerical aperture of a
microscope
True or false
The higher the
numerical aperture, the
higher the resolving
power of a lens
True
Numerical aperture values
are marked as _____ in the
objective lenses
N.A.
Light bending
ability of a medium. Ordinary light has
lower refractive index while
cedarwood oil has higher refractive
index.
Refractive index
Types of microscope
Light microscopes
1.simple
2.compound
3.Stereo, stereoscopic or
dissecting microscope
4.Phase contrast microscopes
5. Fluorescence microscopes
6.Atomic force microscopes
(AFM)
7.Confocal Scanning Laser Microscopes (CSLM)
8.Electron microscopes
Types of Microscopes use
visible light to illuminate cell
structures/specimens
Light microscope
Type of light microscope?
Simple and compound light microscope
Types of light compound microscope?
-bright-field microscopes
-background dark-field
microscopes
Types of light compound microscopes
based on type of illumination where specimen appear dark
against a light
bright-field microscopes
Types of light compound microscopes
based on type of illumination where specimen
appears bright against a
dark background
background dark-field
microscopes
Types of microscope where is an optical microscope variant designed
for low magnification observation of a
sample, typically using light reflected from
the surface of an object rather than
transmitted through it.
Stereo, stereoscopic or
dissecting microscope
Types of Microscope where enhances contrasts
of transparent and colorless objects by influencing
the optical path of light
Phase contrast microscopes
Types of Microscope where are used to study
specimens, which can be made to fluoresce.
Fluorescence microscopes
Types of Microscope where is a very high-
resolution type of scanning
probe microscope
Atomic force microscopes
(AFM)
Types of Microscope where can investigate the
topological surfaces of
biological objects, from
whole cells to protein
particulates and other
materials
Atomic force microscopes
(AFM)
Types of microscope where it obtains high-resolution optical images with depth
selectivity)
Confocal Scanning Laser Microscopes (CSLM)
Types of microscope where it – employ a beam of
electrons instead of a beam of light;
- afford a resolution as much as 1000 fold higher than
the light microscopes
- Magnification as high as 100,000 to 200,000 as
compared to 1000x to 1500x of light microscopes
Electron microscopes
Types of electron microscope?
- transmission electron
microscopes (TEM) - scanning electron
microscopes (SEM)
Types of electron microscope where used to study internal cell
structures or
ultramicroscopic entities
such as viruses and viroids
transmission electron
microscopes (TEM)
Types of electron microscope where used to study internal cell
structures or
ultramicroscopic entities
such as viruses and viroids
transmission electron
microscopes (TEM)
Types of electron microscope where used if only external
features of cells need to be
observed
scanning electron
microscopes (SEM)
