Curricular Resources > 2010 Volume III > Unit 1 (10.03.01) > Section 13

Geomicrobiology: How Microbes Shape Our Planet

The Wonders of Bacteria

Haifa Abdel-Jalil

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Activity 8

Observing Cyanobacteria under the microscope.

Cyanobacteria are oxygenic phototrophs; they are widely distributed in terrestrial, fresh water, and marine habitats. Cyanobacteria can be more tolerant to environmental extremes such as salty lakes, while other species can be found on the surfaces of soil or rocks. Cyanobacteria can be unicellular or filamentous; some of these filaments are branched. They get their name from phycocyanin, a bluish pigment used to capture light for photosynthesis. They also contain chlorophyll a, which is the photosynthetic pigment used by plants for photosynthesis. Cyanobacteria are responsible for fixing a significant amount of carbon dioxide and for producing oxygen on Earth.

Objectives

Students will be able to make a wet mount slide.

Observe the shape and structure of cyanobacteria under the microscope.

Material needed

· Microscope

· Slides

· Forceps

· Pond water or salt marsh water sample

· Pipette

Procedure

1- Use a pipette to take a drop from the sample water and place it in the center of the slide. (Make sure that you can get some of the green stuff on the slide by using the forceps).

2- Gently place a cover slip on the sample, avoid making air bubbles.

3- Use the low-power objective lens to locate the cyanobacteria under the microscope. Turn the coarse adjustment knob until the cells come into focus.

4- You can switch to the medium power (40X) objective to view the slide and see more details of the shape of the cyanobacteria. (cyanobacteria will look like green strings).

5- Observe the cells, draw and label the appropriate parts if you can. Write down the magnification power.

6- Clean the slides carefully, and turn off the microscope

Performance Assessment

1- Draw and label the slides.

2- Describe the shape of the cyanobacteria cells.

3- Describe the color of the cyanobacteria cells.

4- How are these cells similar to plant cells? How are they different?

5- What is the advantage of preparing a wet mount slide and viewing the slide under the microscope?

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·	Microscope
·	Slides
·	Forceps
·	Pond water or salt marsh water sample
·	Pipette

1-	Use a pipette to take a drop from the sample water and place it in the center of the slide. (Make sure that you can get some of the green stuff on the slide by using the forceps).
2-	Gently place a cover slip on the sample, avoid making air bubbles.
3-	Use the low-power objective lens to locate the cyanobacteria under the microscope. Turn the coarse adjustment knob until the cells come into focus.
4-	You can switch to the medium power (40X) objective to view the slide and see more details of the shape of the cyanobacteria. (cyanobacteria will look like green strings).
5-	Observe the cells, draw and label the appropriate parts if you can. Write down the magnification power.
6-	Clean the slides carefully, and turn off the microscope

1-	Draw and label the slides.
2-	Describe the shape of the cyanobacteria cells.
3-	Describe the color of the cyanobacteria cells.
4-	How are these cells similar to plant cells? How are they different?
5-	What is the advantage of preparing a wet mount slide and viewing the slide under the microscope?