In this lesson, we will cover:
Single celled organisms are very near the bottom of the food chain. They feed on bacteria, each other, and some plant material. Plants, of course, like every other living thing, are made out of cells as well. Without cells... all life might be made up of metal! (Protective, but not too great when it gets wet)
So what's, who cares about microscopic life, I live in the real world, that doesn't affect me, right? Wrong. Even the largest mammal in the world is affected, almost directly! The blue whale eats tiny organisms called plankton. These plankton feed directly on single celled animals, and plant matter.
Now you can see the importance of cells in the food chain alone. Next time you take a bite of that pizza, think about where it came from!
Below is a lab experiment that you can try at home. It involves extracting the DNA from an onion.
| First Step | 50 ml warm water (60 degrees centigrade) | Medium onion (approx. 1 cup chopped) |
| small container | soap | thermometer |
| blender | 1 teaspoon salt | 50 ml liquid |
Peel and cut the onion into very small pieces.
Measure out 50 ml of water and add the salt. Stir until the salt is dissolved.
Put the onion pieces and the water in the blender and chop for just a minute or two. The mixture
should still be lumpy, containing small pieces of onion.
Gently stir the onion and water from the blender into the container with the soap.
Set the container in the warm water bath for 15 minutes at 60 degrees centigrade. (Don't go
over the time or temperature!)
After 15 minutes, remove the container from the warm water bath and place it in ice water.
| Second Step | strainer | toothpick |
| coffee filters (3 to 4) | meat tenderizer | small glass container |
Put the coffee filters in the strainer and then the onion mixture.
Filter the liquid into the small glass container. (At this point the mixture does
not need to be kept on ice.)
Add approximately 1/8 teaspoon of the meat tenderizer and gently stir the
mixture with a toothpick.
| Third Step | Ethyl or Isopropyl alcohol at room temperature |
Let the container rest on the table. Slowly pour the alcohol into the small glass container until it is
about an inch over the cell debris.
The alcohol will form a layer on top of the cell debris.
Watch carefully as the DNA precipitates through the alcohol. The DNA is clear. Small bubbles
will attach to the strands as they migrate up through the alcohol. Use the toothpick to gently stir the
alcohol layer. Notice how it moves like snot. The snotty substance is the DNA.
Now that you have extracted DNA from an onion, think about each step of the procedure and why
it works. How did each of the ingredients in the demonstration help extract DNA from the other
parts?
Careers in microbiology are my no means scarce. In fact, there are many job opportunities. You could get a job in the fields of:
Working in areas such as:
That's it! You have made it through lesson 5, the last lesson, and the most important, which teaches you what makes cells so vital to life. There is no quiz for lesson 5, but we encourage you to search out more information on microbiology on your own, or by using our list of resources.