BIO 235 Microbiology Exam 1 Questions and Answers Graded A
4 views 0 purchase
Course
BIO 235
Institution
BIO 235
units of measurement - 1 µm = 10-6 m = 10-3 mm
1 nm = 10-9 m = 10-6 mm
1000 nm = 1 µm
0.001 µm = 1 nm
total magnification (compound microscopes) - -the image from the objective lens is
magnified again by the ocular lens
-total magnification = objective lens x ocular
lens
resolution -...
BIO 235 Microbiology Exam 1 Questions
and Answers Graded A
units of measurement - 1 µm = 10-6 m = 10-3 mm
1 nm = 10-9 m = 10-6 mm
1000 nm = 1 µm
0.001 µm = 1 nm
total magnification (compound microscopes) - -the image from the objective lens is
magnified again by the ocular lens
-total magnification = objective lens x ocular
lens
resolution - -the ability of the lenses to distinguish two points.
-shorter wavelengths of light provide greater resolution
objective lens - lens closest to the specimen
condenser - focuses light onto the specimen
brightfield illumination microscopy - -dark objects are visible against a bright
background
-light reflected off the specimen does not enter
the objective lens
-used for stained microbial cells
darkfield illumination microscopy - -light objects are visible against a dark
background
-light reflected off the specimen enters the objective lens
-used for cells that do not stain easily
phase contrast microscopy - -accentuates the diffraction of a light that passes
through a specimen
, -to facilitate detailed examination of the internal structures of living specimens
DI contrast microscopy - -differential interference
-uses a polarizer to create two distinct beams of polarized light
-typically used on unstained
cells to reveal internal structures
-gives structures such as nucleus, endospores, vacuoles, and granules a three-
dimensional
appearance
fluorescence microscopy - -used to visualize specimens that fluoresce, emitting
light of one color after absorbing light of different color
-some cells naturally fluoresce due to components like chlorophyll, but others have
to be stained with a fluorescent dye
-often rapidly used to detect and identify microbes in tissues or clinical specimens
as well as for enumerating bacteria in a natural environment
confocal scanning laser microscopy - -uses a computerized microscope coupled
with a laser source to generate a 3D image
-computer can focus the laser on single layers of the specimen
-different layers can then be compiled for a 3D image
TEM - -transmission electron microscopy
-uses ultra-thin sections of specimens
-light passes through specimen, then an electromagnetic lens, to a screen or film
-enables visualization of structures at the molecular level
-specimen must be very thin (20-60nm) and be stained with heavy-metal salts
-resolution 0.2nm
SEM - -scanning election microscopy
-specimen is coated with a thing film of heavy metal (like gold)
-an electron gun produces a beam of electrons that scans the surface of a whole
specimen
-secondary electrons emitted from the specimen produce the image
-only the surface of an object is visualized
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller CleanA. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $14.49. You're not tied to anything after your purchase.
