Chapter 3 (EXAM 1) Flashcards
How big is bacteria and how is it looked at
Most are. 2–2.0 µm
Looked at on a scanning or light microscope
describe a light/compound microscope & its path of light
It uses a series of two sets of lenses to magnify the specimen
Light illuminates, illuminator - condenser - through the specimen slide - to the objective lens - to the body tube – through the ocular lens
What is the ocular lens
Made of glass, magnifies the image that is created in the body tube. It passes through the glass specimen & oil. The light is absorbed and reflected from the specimen
What is the objective lens
It is made of glass, focuses and redirects light, magnifies and creates the image
Why is oil immersion used
To direct the light rays up to our eyes, it helps us avoid the spreading of light rays, diffraction
What is diffraction
The breaking up of lights into its rainbow colors
What is the resolution
The ability of a microscope to distinguish between two objects that are close together
What is Brightfield
The path of light/illumination. Produced by regular compound light microscope
Used for stained smears
What is Dark field
Helps us view specimen in liquid and shows us the shape and cillia and presence of extremly small organs
Used to observe unstained cells
What is phase contrast
When we can see direct lights on an altered specimen that travel different paths from light rays.
Two sets of rays are combined at the top increasing the illumination of the specimen
What is confocal
Dark field, allows us to look at a specimen that has not been disorted. It puts together scanned planes, a 3-D view
Describe the electron microscope
Used on anything smaller than zero. 2 µm.
Has a projector lens that focuses the electrons onto the view frame and creates a transmission electron micrograph.
Shows light and dark areas.
Because the illuminating source is a beam of electrons, the lenses are magnetic
Describe a transmission electron microscope
Electrons pass through the specimen, sliced very thin using a glass knife.
Allows us to see through the specimen because they are very thin.
Something we cannot see with the naked eye
Describe the scanning electron microscope
Allows us to see specimens in 3-D and visualize its external structures.
Magnifies many times and has great resolution
What are the scanned probe microscope
AFM
STM
Describe the STM
Uses a tungsten probe.
Allows us to look at the molecular processing ( clotting blood, nerve impulses ).
Able to see the three dimensional surface of atoms & molecules.
It gives us some idea of the chemical magnetic properties and the temperature difference exhibited inside of a cell.
Overall is used more to look at interactions with atoms and molecules, better used by chemist and physicists
How do you perform a smear
Put drop of H2O in the middle of a slide, aseptically add the specimen, smear onto slide making a small stamp, let it air dry 100% on a shelf rack so it dries underneath the slide too, heat fix, stain
What is the purpose of heat fixing
So bacteria sticks to the slide, it allows staining without washing off the bacteria, coagulate proteins so they better absorb the same and it kills the bacteria
What happens if you heat fix for too long
The bacteria will rupture and it will be distorted
What happens if you don’t fully dry the smear before keep fixing
You’ll boil the bacteria
What is simple staining and its stains
A basic/positive stain that is attracted by slightly negative charges inside the cells.
Stains include: crystal violet, safranin, methylene blue, malachite green
What is a negative stain and its stains
Used when you don’t want to heat fix and you want to look at the structures that will wash away in the stating process, capsules and flagla. Stains the background of the cell and leaves the cells clear for us to view
Stains include: nigroson, congo red, Eosin
What is are differential stains
Stains you do beyond in order to determine what bacterial you’re looking at
The stains react differently with different bacteria
describe the acid-fast procedure
Steaming bacteria & using alcohol
Describe a gram stain and its stains along with results
Burstein done to tell us about the bacteria infecting a person and what medication to use
- Add primary stain: Crystal Violet, both will be purple
- Add mordant: iodine, both will still be purple
- Add decolorizer: alcohol, it will destroy the outer lipid membrane so gram-positive = purple gram-negative = clear
- Add counterstain: safranin, gram positive = blue/purple gram negative = pink/red
gram-positive versus gram-negative in medications
Gram positive: antibiotics can destroy its peptidoglycan wall ( penicillin )
Gram negative: will be aggravated by penicillin
What are special stains
Used to show certain structures that cells may have
examples are: capsule staining, endospore staining, flagella staining
Describe capsule staining

Involves a positive and nrgative stain.
Negative staining type that uses a positive stain to stain bacteria on the inside and the negative stain that will stain the back.
Allows us to see a clear halo around the bacteria which are the capsules
Describe endospore staining
Allows us to use malachite green, will stain the endospores, and safranin, will stain rod shaped bacteria, to detect any endospores
Describe a flagella staining
Allows us to see taild, some of may have 1 others might have more.
Uses a negative stain, mordant, to coat the tail and add more and more layers until the tail becomes visible; kind of like painting
After Graham Sting what color are gram negative bacteria and gram positive bacteria
Red/pink and blue/purple
List in order the 4 chemicals used in gram staining
- crystal violet, 2. iodine, 3. alcohol, 4. safranin
What microscope would you use to view intrusellular structures in the natural state ?
A PCM
The smaller the ____ of light, the better the ___ of the microscope
Wavelength, resolution
How do you obtain total magnification of a microscope
Objective lens magnification x ocular lens magnification
Malachite green and safranin are used in what staining?
Endospore staining
What microscope allows specimens to emit light when exposed to UV rays
Fluorescent microscopy
What is accomplished in heat fixing
Kills bacteria, organisms stick to slide, coagulate proteins so they better absorb the state
What is the function of the ocular lens
Re-magnifies the image
When would you use a negative stain
To determine the morphology and cellular arrangement that is too delicate for heat fixing
What are the steps done in lab to view bacterial cells using methaline blue or safferonin
- prepare fixed smears 2. stain 3. allow rest for 1 min. 4. Rinse with water 5. blot dry
Why do mycobacteria tuberculosis appear gram positive although they are not
Because of their waxy mycolic cell wall
What microscope is uses to view a stained bacterial smear
Compound light microscope
What microscope is used to view unstained bacterial cells, small with no detail
Dark field microscope
What microscope is used to view unstained live tissue, some intercelular detail
Phase contrast microscope
What microscope is used to view a sample that emits light when illuminated with uv light
Fluorescence microscope
What microscope is used to view intracelular detail of a cell that is 1 micrometer long
Electron microscope
What microscope is used to view unstained live cell in which intracellular structures are shown

Differential interference contrast microscope
When staining bacillus with malachite green with Heat and a counterstain with safranin, what are the green structures?
Endospores
3D images of live cells can be produced with what microscope
Confocal
Carbolfusuchsin can be used as a simple stain and negative stain, the simple stains PH is ?
Higher then the negative stain
Which is a non functional analogous pair of stains
Nigrosin and malachite green
Which of the pairs is mismatched
None of the above
What stain for capsule
Negative stain
What stain for cell arrangement
Simple stain
What stain for cell size
Negative stain
What stain for bacterial identification
Gram stain
Viewing gram stained of red cocci and blue rods. You can conclude:
Two different species
