Experiment 1: Staining Video
1. Open the Media Player by clicking on the film-strip button in the lower left of the lab's window frame, as shown below. The Media Player is a repository of images, videos, saved snapshots, and more that you will need during the lab.
2. Find and watch the Staing video.
3. The video follows the process of the primary stain method used to identify bacteria - Gram staining.
The RADIANCE Virtual Microscope: Getting Oriented
Since this is the first time you are using the virtual microscope, this activity will help you understand how to use it. This particular microscope is somewhat advanced, but it has the same basic components and controls as all light microscopes.
The microscope is on the Instruments shelf. Place it on the right side of the workbench. Be sure it does not hide the shelf tabs - you still need them. Notice that the Microscope has a view-screen attached to it. This view-screen is connected to the lens and shows you the view through the lenses on top.
Prepared slides are on the Materials shelf. A Microscope Slide is a glass plate on which a specimen has been mounted for viewing. Move your mouse over the slides on the Materials Shelf to view their labels.
Slides are placed on the Microscope stage, the flat surface that the lenses focus on from above. The stage is illuminated by a light source located beneath it. Here is what our Microscope's stage looks like:
Try it:
Find the Amoeba slide on the left side of the shelf. Place it exactly onto the Microscope stage. If you have done this correctly, you will see a loading message in the view-screen at the right of the Microscope.
When the slide loads, you'll see the magnified Amoeba. You are viewing the slide with the 4X objective lens of the Microscope, which is positioned over the center of the slide. The slide you are looking at has a single Amoeba mounted on it. It is a relatively large organism, so it is a good specimen to begin with.
Working comfortably with the Microscope requires getting up close to it. We recommend that you use the lab navigation controls at the bottom-right of the lab to zoom in. Position your view so that everything is within easy reach.
Experiment 2: The Amoeba
1. Place the amoeba slide from the Materials shelf onto the microscope stage again.
2. Use the X-Axis Adjust and Y-Axis Adjust dials on the sides of the stage to center the amoeba on the microscope view screen.
3. Click the objective lens to the right to advance from 4X to 10X magnification. Re-center the amoeba as required.
4. Once the amoeba nearly fills the view screen, observe it and then record a description of its shape in your lab notes.
5. Continue to increase the magnification until you can clearly see the amoeba with its nucleus in the center of the slide. ?
6. Find, label, and save snapshots of the following structures using the microscope's annotation tools at the right of the view screen. You may need to take more than one image to capture all of these structures:
- cell membrane
- cytoplasm
- pseudopod
- nucleus
- food vacuole
7. When you are done, discard the slide. Remember to save your notes.
Experiment 3: The Spirogyra
1. Place the spirogyra slide onto the microscope stage.
2. As before, observe the cells under both low and high power. Record in your notes the shape and color.
3. Find, label, and save snapshots of the following structures:
- cell membrane
- cytoplasm
- nucleus
- chloroplast
- cell wall
4. When you are done, discard the slide. Remember to save your notes.
Experiment 4: Animal Cell Structure - Cardiac Muscle
The heart has many special requirements and thus needs a special type of muscle, cardiac muscle, to perform its functions. Cardiac muscle is not found anywhere else in the body. The output of the heart must adjust rapidly to meet the needs of the organism. With the help of cardiac muscle present, it can increase from about 5 liters of blood/min at rest to more than 25 liters/min in heavy exercise.
1. Place the cardiac muscle slide onto the microscope stage.
2. As before, observe the cells under both low and high power. Record in your notes the shape and color.
3. Find, label, and save snapshots of the following structures:
- cell membrane
- cytoplasm
- nucleus
- intercalated discs
- branching
HINT #1: The cardiac muscle cells are often branched, and contain one nucleus.
HINT #2: A prominent and unique feature of cardiac muscle is the presence of irregularly-spaced dark bands between cardiac muscle cells, or myocytes. These bands are known as intercalated discs, and are due to areas where the membranes of adjacent myocytes come very close together. The intercalated discs have two major functions: one is to ' glue' the myocytes together so that they do not pull apart when the heart contracts; the other is to allow an electrical connection between the cells, which is vital to the function of the heart as a whole. The electrical connection is made via special junctions (gap junctions) between adjoining myocytes, which contain pores through which small ions, and therefore electrical current, can pass.
4. When you are done, discard the slide. Remember to save your notes.
Experiment 5: Bacterial Cell Structure
Part I: Dark Field Microscopy
1. Take the slide labeled bacteria from the slide rack and place it on the stage of the Microscope.
2. Record what you observe in your lab notes. As we discussed the bacteria should be very difficult to visualize using bright field microscopy.
3. Find the field button. It should be set on Bright Field, click on it and it should switch to Dark Field.
4. You probably won't be able to observe the bacteria until you increase to high power, so don't be concerned if you can't see them right away. Describe their shape in your lab notes. Describe any general differences between the appearance of the overall field in Dark Field and Bright Field in your lab notes.
5. Observe and label the following structures:
o cell membrane
o cytoplasm
6. Stick a label in one of the corners and record the magnification you are using.
7. Take a snapshot of the slide with labels.
Part I: Phase Contrast Microscopy
1. Click on the Field button to switch to Phase Contrast.
2. Does the shape of the bacteria change in this different field? Describe their shape in your lab notes. Describe any other differences between Phase Contrast, Dark Field and Bright Field in your lab notes.
3. Observe and label the following structures:
- cell membrane
- cytoplasm
4. Take a snapshot of the slide with labels.
Attachment:- Microbial Diversity Lab.rar