Prokaryotic Cell Lab - Honors
“Looking at Bacteria”
Name: ______
Date: ______
Class Period: ______
______/ 23 = ______%
Objective: To observe the size, shape, and structure of prokaryotic cells, to be able to compare them later to eukaryotic cells.
Introduction:
Bacteria are prokaryotic cells. Bacteria have three basic shapes:
bacillus (rod-shaped) coccus (sphere-shaped) spirilla (spiral shaped).
Bacteria can also arrange themselves into colonies. Each arrangement is given a special name.
The prefix Diplo means 2 ex: diplococcus, a pair of sphere-shaped bacteria.
The prefix Strepto-, meaning chain ex: streptobacilli, a chain of rod-shaped bacteria.
The word Tetrad, means 4. Note: this is not a prefix. You would just say "tetrad cocci bacteria"
The prefix Staphylo-, meaning random ex: staphylococcus, a random arrangement of sphere-shaped bacteria.
Scientists and doctors can identify bacteria by their shape and arrangement. For example, if you've ever had strep throat, the doctor probably took a sample from your mouth or throat. They are looking for bacteria that are spherical and in chains. The technical name of this is streptococcus. Hence the name: strep throat.
Procedure Part One: Microscopes are set up displaying the three shapes of bacteria. You will draw each shape under the oil immersion power. Sketch your drawing below. (3pts)
bacillus coccus spirilla
Part Two Introduction:
Blue-green algae are not a type of algae but rather a type of bacteria called cyanobacteria. Cyanobacteria are single-celled prokaryotic organisms and are the simplest life forms. They produce their own food by photosynthesis like plants, but cyanobacteria cells are simpler and lack some of the structural characteristics of these eukaryotic organisms. You would recognize this bacteria as the green scum that covers some ponds and lakes.
Procedure Part Two:
Obtain a prepared slide of blue-green bacteria/algae from your teacher. Draw the bacteria under high power. (1pts)
Introduction Part Three:
As you can see, bacterial cells are very tiny. It is very hard to see cell parts using a light microscope. In order for you to see the cell parts of bacteria you will need to look below.
Name and define the function of each part labeled in the bacterial cell from Introduction Part Three. USE YOUR NOTES!
1. Cytoplasm:
2. Flagellum (Flagella):
3. Ribosome:
4. DNA:
5. Cell wall:
6. Plasma membrane
Analysis Questions:
Identify the shape and colony type of each bacteria picture shown below. See the front page of the lab for help.
1. ______
2. ______
3. ______
4. ______
6. Are bacterial cells prokaryotic or eukaryotic? Give 2 reasons to support why. (2 points)
7. What are the 4 cell parts that are shared between prokaryotic and eukaryotic cells? (4 points)
ON LOOSELEAF: Write a short conclusion to this lab. Include a discussion of the three shapes of bacteria and the cell parts that all cells have. (3pts)