1
MMG 301 Exam 1 Learning Objectives
Questions with Correct Answers | Updated
(100% Correct Answers)
Light Microscopes Answer: Have glass lenses and show structure
and function of microorganisms; visualize samples with staining with
colored chemicals
Electron Microscopes Answer: Uses a beam of electrons rather than
visible light that passes through the specimen; used to study cell
internal structure and surfaces with high reolution and high
magnification
How is immersion oil beneficial to light microscopy? Answer:
Increases the amount of light passing through specimen
Numerical Aperture (NA) Answer: Estimate the smallest observable
object, printed on the objective
Resolving Power Answer: Smallest object resolved
(0.5x*wavelength)/NA
wavelength of light used
Gram Staining Answer: 1. Flood heat-fixed smear with crystal violet
for 1 minute (all cells purple
© 2025 All rights reserved
,2
2. Add iodine solution for 1 minute (all cells purple)
3. Decolorize with alcohol briefly (20s) (gram-positive=purple; gram-
negative=colorless)
4. Counterstain with safranin for 1-2 minute (gram-positive=purple;
gram-negative= red)
Acid-Fast Staining Answer: 1. Small amount of organism suspended
in saline solution is fixed on a slide (no color)
2. Slide is flooded with carbol Fuchsin and phenol for 3 minutes,
and gently rinsed with water (both=fushia)
3. Slide is decolorized with 3% HCl in 70% alcohol until color
appears to be removed and rinse with water (acid-fast=fushia; not
acid-fast= no color)
4. Slide flooded with methylene blue counterstain for 30 sec, rinsed
with water and air-dried (acid-fast= fushia; not acid-fast=blue)
Phase Contrast Microscopes Answer: -converts differences in
refractive index within unstained cells into contrast
-provides improved constrast between unstained bacteria and
surrounding medium
-light collected in phase ring (amplify difference in cells and
converts them to contrast)
© 2025 All rights reserved
,3
-examine morphology of live cells
Dark Field Microscopes Answer: -allows visualization of thin cells on
dark background
-utilizes cardioid (dark-field) condenser between light source and
specimen
-produces "hollow cone of light"
-objects appears bright against dark background
-ideal for examining thin cells
-illuminate= light reaching specimen is scattered
How is a specimen illuminated in darkfield microscopy? Answer:
Produces a hollow cone of light and the light reaching the specimen
is scattered
What do cells look like when viewed in a fluorescence microscope?
Answer: -Cells colored against a dark background
-Illuminate species from above and observing fluorescence on a
dark background
Fluorescence Microscope Answer: Light comes in from the side in
between the ocular and objective lenses
© 2025 All rights reserved
, 4
Transmission Electron Microscope Answer: -passes beam of
electrons through a specimen
-resolves internal ceel structures and thin external appendage on
bacteria
-visualize details down to molecular level
-slide prep=dried cells --> plastic --> slice
Scanning Electron Microscopes Answer: -visualize surfaces
-move focused beam of electron over surface of specimen
-image created from secondary electron emitted off object surface
-sample prep= dry sample coated with metal ions
-high depth of field
-view surfaces colonized by bacteria
Ester lipids Answer: -Backertia and eukaryotes have easter lipids
Ether lipids Answer: -Ether lipids of Archaea can form lipid bilayers
or monolayers
Fluid Mosaic Model of Membrane Structure Answer: The fluid
mosaic model of membrane structure is the "fluid" characteristic of
the membrane that allows proteins to move relative to each other.
© 2025 All rights reserved
MMG 301 Exam 1 Learning Objectives
Questions with Correct Answers | Updated
(100% Correct Answers)
Light Microscopes Answer: Have glass lenses and show structure
and function of microorganisms; visualize samples with staining with
colored chemicals
Electron Microscopes Answer: Uses a beam of electrons rather than
visible light that passes through the specimen; used to study cell
internal structure and surfaces with high reolution and high
magnification
How is immersion oil beneficial to light microscopy? Answer:
Increases the amount of light passing through specimen
Numerical Aperture (NA) Answer: Estimate the smallest observable
object, printed on the objective
Resolving Power Answer: Smallest object resolved
(0.5x*wavelength)/NA
wavelength of light used
Gram Staining Answer: 1. Flood heat-fixed smear with crystal violet
for 1 minute (all cells purple
© 2025 All rights reserved
,2
2. Add iodine solution for 1 minute (all cells purple)
3. Decolorize with alcohol briefly (20s) (gram-positive=purple; gram-
negative=colorless)
4. Counterstain with safranin for 1-2 minute (gram-positive=purple;
gram-negative= red)
Acid-Fast Staining Answer: 1. Small amount of organism suspended
in saline solution is fixed on a slide (no color)
2. Slide is flooded with carbol Fuchsin and phenol for 3 minutes,
and gently rinsed with water (both=fushia)
3. Slide is decolorized with 3% HCl in 70% alcohol until color
appears to be removed and rinse with water (acid-fast=fushia; not
acid-fast= no color)
4. Slide flooded with methylene blue counterstain for 30 sec, rinsed
with water and air-dried (acid-fast= fushia; not acid-fast=blue)
Phase Contrast Microscopes Answer: -converts differences in
refractive index within unstained cells into contrast
-provides improved constrast between unstained bacteria and
surrounding medium
-light collected in phase ring (amplify difference in cells and
converts them to contrast)
© 2025 All rights reserved
,3
-examine morphology of live cells
Dark Field Microscopes Answer: -allows visualization of thin cells on
dark background
-utilizes cardioid (dark-field) condenser between light source and
specimen
-produces "hollow cone of light"
-objects appears bright against dark background
-ideal for examining thin cells
-illuminate= light reaching specimen is scattered
How is a specimen illuminated in darkfield microscopy? Answer:
Produces a hollow cone of light and the light reaching the specimen
is scattered
What do cells look like when viewed in a fluorescence microscope?
Answer: -Cells colored against a dark background
-Illuminate species from above and observing fluorescence on a
dark background
Fluorescence Microscope Answer: Light comes in from the side in
between the ocular and objective lenses
© 2025 All rights reserved
, 4
Transmission Electron Microscope Answer: -passes beam of
electrons through a specimen
-resolves internal ceel structures and thin external appendage on
bacteria
-visualize details down to molecular level
-slide prep=dried cells --> plastic --> slice
Scanning Electron Microscopes Answer: -visualize surfaces
-move focused beam of electron over surface of specimen
-image created from secondary electron emitted off object surface
-sample prep= dry sample coated with metal ions
-high depth of field
-view surfaces colonized by bacteria
Ester lipids Answer: -Backertia and eukaryotes have easter lipids
Ether lipids Answer: -Ether lipids of Archaea can form lipid bilayers
or monolayers
Fluid Mosaic Model of Membrane Structure Answer: The fluid
mosaic model of membrane structure is the "fluid" characteristic of
the membrane that allows proteins to move relative to each other.
© 2025 All rights reserved
