Lab Exam 1 Flashcards
What is the power of the ocular lens in a microscope?
10x
What are the powers of the four objective lenses on our microscopes?
- Scanning lens (red): 4x
- Low power magnification (yellow): 10x
- High power (blue): 40x
- Oil immersion (grey): 100x
What is the purpose of the immersion oil?
The light rays at the highest magnification can be retained.
Which objective lens requires immersion oil?
The 100x magnification
What are the three basic steps for prepping a smear?
- Two loopfuls of bacteria on the target circle
- Air dry for a maximum of 10 mins
- Pass slide through flame at least 6 times
Why do we fuse bacteria to the slide?
To make sure that the bacteria is not washed off whenever we run a liquid over them.
Why do we flame during the preperation of a smear?
We heat-fix the slide so that we kill the bacteria on the slide. This ensures the bacteria stays there. This also keeps the bacteria’s structual integrity.
Why do we flame the tube, the loop, and the slide?
- We flame the slide to kill bacteria and keep them on the slide.
- We flame the tube and loop to kill any lingering bacteria. We don’t want to spread bacteria in lab.
What is a wet mount? What are it’s pros and cons compared to a smear?
- A wet mount is a fluid solution on a slide, mixed with a specimen
- Pro: Wet mounts are better for bacteria and protozoans
- Con: Takes more time to prepare slide. Easily dries out, so if the procedure is long, you must be careful of it drying out
What microbes did you see when using the wet mount that were autotrophs?
- Algae (Diatoms)
What microbes did you see when using the wet mount that were heterotrophs?
- Protozoa
Why do we stain microorganisms?
To paint that microorganims a color so that we can view them better under a microscope. We can see their size and shape.
How is a simple stain different from a differential stain?
- Simple stain uses one staining reagent to paint microorganism
- While differential stain uses two or more staining reagents to paint microorganism
What are the names and colors of the two simple stains that we use in our lab?
- Methylane Blue- Blue
- Crystal Violet- Purple
What are the four basic steps and purpose to a differential staining procedure.
- Crystal Violet
- Gram Iodine
- Discolorizer
- Safranin
Washing in netween stains, mordant, and discolorizer.
When is the simple stain used as part of the differential staining protocol?
The very first step of putting Crystal violet of the smear. The purpose of this is to stain the bacteria. If it is a gram-positive the cells will be purple, if it is gram-negative the cells will be pink. The reason is because the decolorizer will remove the crystal violet off the gram-negative, it will NOT remove the crystal violet off the gram-positive.
Endospore Staining (Schaeffer-Fulton Method
What is the primary stain?
Malachite green is the primary stain in the endopore staining.
What is the function of the rotatable head in a microscope?
The rotatable head swivels and holds prisms.
What is the function of the mechanical stage in a microscope?
The mechanical stage is a flat platform that the slide rests on.
What is the function of the illuminator in a microscope?
The illuminator is the light source of the microscope.
What is the function of the condenser in a microscope, and what special feature does it have?
The condenser directs light onto the sample and includes a blue filter to increase resolution.
What is the function of the diaphragm in a microscope, and where is it located?
The diaphragm regulates the amount of light passing to the sample and is located within the condenser.
What is the function of the rotatable nosepiece in a microscope?
The rotatable nosepiece turns to change the objective lens power.
What is the function of the objective lenses in a microscope, and how many power options are typically available?
The objective lenses are closer to the slide and provide different magnification options. Typically, there are four power options, such as 4X, 10X, 40X, and 100X.
What is the function of the fine adjustment knob in a microscope?
The fine adjustment knob raises and lowers the slide by small amounts to bring objects into focus.
What is the function of the coarse adjustment knob in a microscope?
The coarse adjustment knob raises and lowers the slide by large amounts to bring objects into focus.
What is the function of the stage adjustment in a microscope?
The stage adjustment is a metal clamp that holds the slide in place.
