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
