Prokaryote Lab
Question: What area has the most bacteria?
Research: Read the following information and answer the questions below.
Bacteria shapes: If you were to look at bacterial cells under a microscope, you would notice that bacterial cells have 3 basic shapes:
round, rod, or spiral shaped. The shape helps scientists identify the type of bacteria. For example, the bacteria that cause strep
throat are spherical.
Bacteria Structures: The cells of bacteria differ from the cells of other organisms in many ways. The genetic material, DNA, in a
bacterium (singular) is not contained in the nucleus, and so bacteria are classified as prokaryotes. Organisms like humans have their
genetic material in the cell nucleus and are classified as eukaryotes. The shape of the bacteria is determined by the chemicals in the
cell wall. The cell wall that surrounds most bacteria is rigid and helps protect the cell. The cell wall is the outermost structure. Inside
the cell wall is the cell membrane which controls what goes in and out of the bacterium. The region inside the cell is the cytoplasm.
Floating inside the cytoplasm are tiny structures called ribosomes. Ribosomes produce proteins for the cell. The bacterium’s genetic
material looks like a thick tangled rubber band. The genetic material contains all the information for the bacterium’s functions.
Bacteria Nutrition: Bacteria need food for energy to grow. They can get their energy from sugars found in nature like table sugar and
sugar in fruits. They can even use the starch (a type of sugar) that is found in plants like potatoes.
Answer the following questions.
1. How many basic shapes do bacteria have? ________________________________________
2. Name the basic shapes. ______________________________________________________
3. What does the cell wall do? ___________________________________________________
4. What does the cell membrane do? _____________________________________________
5. Where is the bacterium’s genetic material found? _________________________________
6. Where do bacteria get their energy? ____________________________________________
7. Why do bacteria need energy? _________________________________________________
8. What are the 3 areas that you will be testing for the highest growth of bacteria? _________
__________________________________________________________________________
Hypothesis: Using what you know about bacteria, write a logical and reasonable hypothesis.
If we allow bacteria from the desk, door handle, and cell phone to grow, then the
___________________ will have the most colonies of bacteria growing. Our reason for this is
__________________________________________________________________________.
Procedure:
1. Your teacher will give you a petri dish that has agar. Agar is a thick gel containing sugar. It is food for
bacteria. PLEASE DO NOT OPEN THE PETRI DISH.
2. Your teacher will give you a sterile Q-tip. Make sure you don’t touch anything, including your fingers, to
the cotton side of the Q-tip.
3. Rub your cotton side of the Q-tip on the place you are testing. Follow the guidelines below:
a. Seat A: Don’t touch your Q-tip to anything.
b. Seat B: Rub your Q-tip on the door handle of one of the exit doors.
c. Seat C: Rub your Q-tip on your table top.
d. Seat D: Rub your Q-tip on a cell phone (anyone’s cell phone is fine)
4. Now open the top of the petri dish and rub your Q-tip on the agar in the appropriate quadrant.
a. Seat A will rub their Q-tip on quadrant 1 (control)
b. Seat B will rub their Q-tip on quadrant 2 (door handle)
c. Seat C will rub their Q-tip on quadrant 3 (table top)
d. Seat D will rub their Q-tip on quadrant 4 (cell phone)
5. Quickly put the cover on the petri dish.
6. Draw your petri dish on Day 1 on the data table and record observations.
Data Table
Day 1: Date ___________________________
Day 2: Date ____________________________
Observations: _________________________
____________________________________
____________________________________
Observations: _________________________
____________________________________
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Day 3: Date ___________________________
Day 4: Date ____________________________
Observations: _________________________
____________________________________
____________________________________
Observations: _________________________
____________________________________
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