•
CHAPTER 3 LECTURE - MICROSCOPES
•
Microscopic Instruments differ in their _______ and the source of their __________
•
Microscopes
•
All microscopes operate on the same basic principles
•
–
______ is projected toward an object (MO)
–
Energy bounces off of the object and creates an _________ on a sensing
device
–
The device can be a TV screen, a piece of film or the _________ ______
–
The image reveals the ______, ______, ______ and ____________ features of
the object
I. LIGHT MICROSCOPE
_______ ______ illuminates the object
•
A. STEREO MICROSCOPE (SM)
•
_______ _______ for a light source
•
Magnification of _____X
•
Surface picture (_____)
•
B. COMPOUND MICROSCOPE (CM)
•
Most commonly used – ___ ______
•
________ lens – 10X
•
__________ lenses
•
•
10X, 40X, 100X
Some can even go to
2000X
•
B. COMPOUND MICROSCOPE (CM)
•
______ ______ for light source
•
Light goes ________ object
•
Small or _____ ______ object
•
______ and _______ of
bacteria cell can be seen
•
II. ELECTRON MICROSCOPE
Thousand times better than a light microscope.
•
II. ELECTRON MICROSCOPE
•
German physicist Ernst _______
•
Showed that ________ can flow in a sealed tube if a ________ is maintained
•
_________ can be used to
pinpoint the flow of
electrons onto
an object
•
II. ELECTRON MICROSCOPE
•
Depending upon the ________ of structures in the object, the electrons are either
__________ or ___________
•
The electrons form an _______ that can be projected onto a screen and outlines the
___________ in the object
•
A. TRANSMISSION ELECTRON MICROSCOPE (TEM) 1931
•
Used to see _______ cell structures in detail
•
_________ sections of a specimen must be prepared because the electron beam can
only penetrate matter a ________ distance
•
Sections are floated in _______ and picked up on a wire grid
•
Sections are inserted into the ___________ __________ of the microscope
•
Electrons ___________ the specimen
•
A. TRANSMISSION ELECTRON MICROSCOPE (TEM) 1931
•
Magnetic field _________ the
beam of electrons (as
condenser lens of light
•
No ocular lens, electrons hit
electron sensitive screen to
create image
•
__________X – Strongest
Microscope
•
B. SCANNING ELECTRON MICROSCOPE (SEM) 1960’s
•
Permits the _________ of objects to be seen without having to make _______
___________
•
Specimens are placed in the vacuum chamber and coated with a thin layer of
_______ to increase ____________
•
The electron beam sweeps across the object and knocks loose _________ ___
____________
•
B. SCANNING ELECTRON MICROSCOPE (SEM) 1960’s
•
A _____ image builds line by line like a TV receiver – can see surface detail
•
Can magnify _____X – __________X
•
See image on TV screen
•
B. SCANNING ELECTRON MICROSCOPE (SEM) 1960’s
•
III. VARIATIONS
Manipulation of Light
•
A. DARK-FIELD MICROSCOPE
•
Highlights specimen against a _______ background – only _______ is illuminated
•
Light scattered and hits object from different angles
•
Like us seeing the moon at night because sunlight from behind the earth reflects off
the moon
•
A. DARK-FIELD MICROSCOPE
•
Good for _______ MOs to see size, shape and motility
•
Helps in __________ of some diseases caused by _______ bacteria because they are
so small
•
Treponema palladum causes syhphilis and is identified from scrapings of the infected
_________
•
B. PHASE CONTRAST MICROSCOPE
•
Used in research labs for observing ________ MO and their _________ in medium
where they are growing – no staining
•
Same magnification as compound microscope but it detects small differences in
__________
•
Compound microscope that increases the contrast between _________ MOs and
surrounding medium (MO denser than medium)
•
B. PHASE CONTRAST MICROSCOPE
•
C. FLUORESCENCE MICROSCOPE
•
MO’s are coated with ____________ ______ and illuminated with UV light
•
Coated MO’s appear to fluoresce
•
Applications in
_________ microbiology
tagged antibodies
•
D. SCANNING TUNNELING MICROSCOPE (STM) 1981
•
Focus on surface of object, produce a map showing _______ and ________ of
_______
•
Map surface as blind person with a cane (tap)
•
No special prep to sample