Kingdom Monera: Bacteria
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| Student notebook page (10th grade) |
Kingdom Monera is basically Bacteria -the tiny little living things -so small that 1,000 of them would fit easily side-by-side in a dot on this "i". Bacteria are prokaryotic which means that they are single-celled organisms that are not "membrane-bound." The DNA strand, which is a single circular strand, is not bound inside a nucleus but is simply suspended in the cytoplasm. They also only have one type of organelle - ribosomes. The first way we separate the organisms in kingdom Monera is by their cell walls. If a bacterium has a complex cell wall (Gram-negative) it belong to phylum Gracilicutes. If the cell wall is rather simple (Gram-positive), it belongs to phylum Firmicutes. If they have no cell wall, they belong into phylum Tenericutes. Some bacterial posses a cell wall, but the compounds which form these walls are different than those of the phylums Gracilicutes and Firmicutes, than it is in the phylum Mendosicutes.
In phylum Firmicutes, the classes are determined by their shape.
Bacteria come in three basic shapes.
The shape of the bacterium is in its name. For instance, Staphylococcus pharyngitis is the name for strep throat, and from the name, you can tell that the bacteria are spherical (cocci). They are sometimes in colonies, not just a single bacterium by itself. There are other ways in which we categorize bacteria, however.
Bacteria can be aerobic or anaerobic, meaning they may or may not need oxygen.
Phylum Gracilicutes have three classes, which are based on their metabolism. Class Scotobacteria is composed of the non-photosynthetic bacteria. Many pathogenic bacteria can be found here.
Heterotrophic bacteria get their food from other sources. If they are decomposers, they are saprophytic; they feed on non-living things.
If heterotrophic bacteria are parasitic, they feed on a living host. Autotrophic bacteria make their own food either by photosynthesis (energy from sunlight) or by chemosynthesis (chemical reactions which release energy). Class Anoxphotobacteria, is composed of photosynthetic bacteria that do not produce oxygen, and Oxyphotobacteria, as you can probably tell from its name, is composed of photosynthetic bacteria that produce oxygen.
Bacteria can be aerobic or anaerobic, meaning they may or may not need oxygen.
We also took this opportunity to complete a nature study of bacteria, the object being a lesson to enforce cleanliness. We made up some unsweetened gelatin according to the directions on the packet. We poured some into four little disposable cups and let it cool. I then invited the boys to place their unwashed hands on the gelatin in two of the cups. I then got them to wash their hands and do the same with the second set of cups of gelatin. We covered the two plates and left them in a cool, dark place for a few days.
This is one of the cups that was touched with dirty hands. Can you see the cloudy spots throughout the gelatin? It is a bit hard to see. These are the places with bacterial colonies. The ones with washed hands did not have them. (I neglected to get pictures of them, since they didn't change.) We then explored the questions in Lesson 206 of the Handbook of Nature Study.
We also took this opportunity to complete a nature study of bacteria, the object being a lesson to enforce cleanliness. We made up some unsweetened gelatin according to the directions on the packet. We poured some into four little disposable cups and let it cool. I then invited the boys to place their unwashed hands on the gelatin in two of the cups. I then got them to wash their hands and do the same with the second set of cups of gelatin. We covered the two plates and left them in a cool, dark place for a few days.
Most people think of bacteria as harmful, and they can be, but there are also friendly bacteria. These are found in milk and yogurt, as the process of making yogurt involves culturing milk with live and active bacterial cultures. There are also friendly bacteria in your own body, including the ones that are responsible for the digestion of your food.
It is so much fun to collect a water sample from a nearby pond and see if you can identify the interesting microscopic creatures found there...
but if you don't have access to a pond and/or microscope, you can use this as your virtual pond.
What can you identify?
Culturing pond water, or adding things to the jar of pond water in hopes of encouraging microorganisms to grow and reproduce, can produce even more interesting creatures to see, sketch and study. You can add a small amount of hay, rice, egg yolk or soil (or try adding each to four separate jars.) Take the jars and place them in an area of subdued light and leave them for about 3 to 5 days.
Culturing pond water, or adding things to the jar of pond water in hopes of encouraging microorganisms to grow and reproduce, can produce even more interesting creatures to see, sketch and study. You can add a small amount of hay, rice, egg yolk or soil (or try adding each to four separate jars.) Take the jars and place them in an area of subdued light and leave them for about 3 to 5 days.
Some are Monera but some are Protista, which we will get to next time.
sources and inspiration:
- Exploring Creation with Biology, Jay Wile
- Handbook of Nature Study, Anna Botsford Comstock, Lesson 206: Bacteria
- Sahm I Am!
- Virtual Pond Dip
- Homeschooler's Resources (lots of videos)
- Healthy Habits at Totally Tots, Glitter Germs at Kids Activity Blog, or Glo Germs
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