One place where bacteria can be found is on your teeth. This is why it’s so important to brush well. Don’t believe me? Then this experiment is for you. You’ll need to gather your materials and make sure you have a toothbrush and microscope nearby.

This is important because prokaryotes are incredibly common and have a huge impact on our lives.  You may already know some of the ways bacteria can be harmful to you, and this is certainly important information.  Scientists have used knowledge of prokaryotes to create medications, vaccines, and healthy living habits that have led to a healthier life for billions of people.

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Materials:

• water
• toothbrush
• microscope with coverslips and slides

Experiment:

1. Place a drop of water on a microscope slide.
2. Gently brush your toothbrush against your teeth and then apply the saliva from the brush to the slide.
3. Add a cover slip, and observe under the microscope. Draw what you see.

Here’s a short video on a real bacterial colonization of the mouth after only 8 hours of having a cleaning done at the dentist:

If you’ve ever gone to the store to buy toothpaste, you know there many brands. Do any actually do a better job of getting rid of bacteria on your teeth? This is a great question for the scientific method. Here’s what you do:

1. Brush your teeth really well.
2. Swab your teeth with a cotton ball and apply to a petrie dish of agar.The next day, brush with a different brand of toothpaste, and again, swab and apply to a different dish.
3. Repeat for five days with five different brands. Record the growth of bacteria on each dish for each day.
4. Remember that “day 1” for the first dish will be different than “day 1” for the second dish, and so on.
5. Which brand left the fewest bacteria? Could there be factors that caused the difference besides toothpaste brand? (Hint: Do you eat the same thing every day?)

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Ah-chooo! Influenza (the “flu”) is when you get chills, fever, sore throat, muscle pains, headaches, coughing, and feel like all you want to do is lie in bed. The flu is often confused with the common cold, but it’s a totally different (and more severe) virus.

The flu is passed from person to person (or animals or birds) by coughing or sneezing. With plants, it’s transmitted through the sap via insects. In the case of birds and animals, the flu is usually transmitted by touching their droppings, which is why hand-washing is so important! In addition to soap, the flu virus can be inactivated by sunlight, disinfectants and detergents.

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A virus can only replicate inside the living cells of organisms, and most are way too small to be viewed through a microscope. Viruses can infect organisms, animals, plants, bacteria and archaea. Virus particles (virions) are made up of two or three parts, including the genetic material (from either DNA or RNA), long molecules which bring genetic information, and a special coat that protects the genes.

Viruses can be helical or complex structures, but they are a lot smaller than bacteria usually by about a hundredth.

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Birds, people, plants, and microscopic organisms need to know where they are as well as where they want to be. Birds migrate each year and know which way is south, and plants detect the sun so they can angle their leaves properly. People consult a map or GPS to figure out where they are.

Magnetotactic bacteria orients itself along magnetic field lines, whether from a nearby magnet or the Earth’s magnetic field. It’s like having a built-in internal compass.

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Discovered in 1975, scientists noticed that certain bacteria seemed to move to the same side of the microscope slide. After placing a magnet near the slide, they were able to determine these bacteria contain tiny bits of iron (magnetic crystals, to be exact). The bacteria place the iron (which act like magnets) in a line to make one long magnet, and use this magnet to align to the earth’s magnetic field, just like a compass.

Bacteria move away from oxygen and toward areas with low (or no) oxygen. In water, oxygen levels decrease with depth, so you’ll find magnetotactic bacteria in the deeper parts. These bacteria use their internal compass to figure out which way is deeper.

Since the Earth’s geomagnetic north pole actually points at an angle, the “north-seeking” bacteria aligned to the field lines are also pointing down. When the bacteria move north along the field lines, they are moving into deeper water (with less oxygen). On the flip side (Southern Hemisphere), magnetotactic bacteria must be “south-seeking” in order to go deeper. Of course, at the equator, there’s a mixture of north-seeking and south-seeking bacteria.

Since the magnetic crystals are found in the organisms, even dead cells will align themselves!

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All living things need a way to get energy. Bacteria get their food and energy in many ways. Some bacteria can make food on their own, while others need other organisms.

Some bacteria help other living things as they get energy, others hurt them while they get energy, and still others have no affect on living things at all.
Some living things, or organisms, are able to make their own food in a process called photosynthesis.

In this process, the organism turns energy from the sun into energy that can be used for energy. Organisms that get their energy from photosynthesis are called autotrophs. Some bacteria get their energy this way.

Some bacteria, called chemotrophs, get their energy by breaking down chemical compounds in the environment, including ammonia. Breaking down ammonia is important because ammonia contains the element nitrogen.

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All organisms need nitrogen to survive, and the nitrogen released by bacteria is crucial to these living things’ survival. Clearly, chemotrophs are very important and beneficial to other living things. Living things that cannot get their energy through photosynthesis or from breaking down chemical compounds have to get their energy from other living things. Some bacteria, called decomposers, get their energy by breaking down dead organisms or waste products into simple nutrients and energy.

Pseudomonas bacteria are decomposers found in the soil, where they recycle dead plant material. The last groups of bacteria get energy from organisms that are still alive, and depend on these organisms to survive.
Mutualistic bacteria get their energy in ways that help another organism. For example, some bacteria live in the roots of legumes, including pea plants. The bacteria make the nitrogen the pea plants need and the pea plants provide a place for the bacteria to live. Other bacteria, called parasitic bacteria, hurt the organism they are getting help from. For example, some bacteria cause illness. We will talk about ways bacteria can be helpful or harmful a little later.

All living things reproduce. This is the only way to ensure the organisms continued survival. Bacteria reproduce asexually. This means that a single “parent” organism produces offspring on their own. In the case of bacteria, a process called binary fission is used. In binary fission, the DNA in the nuceleoid region and plasmids double, and the bacterium splits into two identical copies. If everything happens the way it’s supposed to, the two new bacteria will be identical to the original bacterium. These bacteria can then split again to increase the number of bacteria in the population. Through binary fission, bacteria reproduce very quickly. Some populations can double their size in less than ten minutes!

How to Grow Your Own Bacteria

Although we often think of bacteria as things that cause disease, some bacteria are very helpful. In fact, if you like to eat yogurt, you are eating helpful bacteria all the time! See for yourself in these two activities:

Materials:

• clean plastic cup
• yogurt
• dropper or toothpick
• microscope with slides and coverslips

1. Place a very small portion of plain yogurt onto the slide, and add one drop of water. Place the coverslip on top.
2. Under low power, find a section where the yogurt is pretty thin; this is where you will find the bacteria.
3. Switch to high power (400X for most microscopes) for a better view of the bacteria.
4.  Make a sketch of your view under different magnifications.

Finding Bacteria in Yogurt

Materials:

• clean plastic cup
• yogurt
• toothpick
• water
• microscope with slides and coverslips

1. Clean a small plastic cup. Make sure ALL soap is completely rinsed off.
2. Put a small amount of yogurt in the cup, and put it aside in a dark, relatively warm area. Leave undisturbed for at least 24 hours.
3. After the time has past, take a small sample with a toothpick and place on a slide. If the sample seems too thick, dilute with a drop of water. Next, place a cover slip on top.
4. First observe the bacteria at low power 100X to find a good place to start looking. The diaphragm setting should be very low (small) because these bacteria are nearly transparent.
5. Switch into the highest power to identify the bacteria according to arrangement.
6. From here you can identify any bacteria you might find. For example, a common inhabitant of yogurt is a paired, round bacteria or diplococcus (see list below)
7. Did you observe more bacteria in part 1 or 2? Why do you think this is?
8. Do you want to take it a step further? Think about all the kinds of yogurt out there. There are different flavors, different brands, some that are non-fat, and much more. Do some types have more bacteria than others? This is a great question to investigate using the scientific method. So come up with a specific question, write a hypothesis, grab some yogurt, and get experimenting!

Bacteria are classified as follows:

First observe the way the bacteria are arranged:

• paired = diploe
• chained = streptose
• clusters = staphyle

Next observe the shape of the bacteria:

• round = coccus
• rod = bacillus
• spiral = spirillum

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Bacteria have a bad reputation. Walk down the cleaning aisle of any store and you’ll see rows and rows of products promising to kill them. There are definitely some bacteria that cause problems for people, and we’ll talk about them soon, but we are going to start off positive, and talk about the many ways bacteria can be helpful.

First, decomposers help control waste. Without these bacteria, the amount of waste in soil would quickly make the soil a place where nothing could grow. Bacteria are even used in sewage treatment plants to treat our waste. Decomposers also help provide organisms with nitrogen, as was discussed earlier.

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Bacteria also have an important role in the foods we eat. Yogurt and some cheeses are made from using bacteria to ferment milk, and sauerkraut is made from using bacteria to ferment cabbage.

Once we’ve eaten, bacteria continue to help us. Bacteria line the digestive tract and help us digest food. In your gut, the number of bacteria cells is greater than the number of your own cells.

In science labs, researchers have found ways to use bacteria to produce medicines. For example, some people with the disease diabetes need insulin. Mass-produced insulin, made possible by bacteria, has lowered the cost of insulin for people suffering from this disease.

Researchers from Japan’s National Institute of Advanced Industrial Science and Technology (AIST) have figured out a way to get motion from bacteria. This team of scientists have developed a motor that is powered by bacteria movement.

Because this motor is so small (it’s only 20-microns across, where 1 micron = 1 millionth of a meter), we’ve posted a picture (above) so you can see the six revolving motor blades. Each blade has a tab that sits in a circular groove area, which is treated with a substance that makes the bacteria move only in one direction. As the bacteria moves, they push the tabs (which spins the motor). This is a great way to get power for tiny devices, such as tiny pumps inside medical devices.

What is true about bacteria is that they are made of only a single cell, are prokaryotes, and are very common. They are the most common living things on Earth. In fact, there are more bacteria living in the mouth of a single person than there are people on the planet!

Since bacteria are made of only one cell, they are very cell. The only way to see bacteria is to look at them in a microscope. When you look at bacteria in a microscope, they usually have one of three shapes.

Bacilli are shaped like rods, cocci are shaped like spheres, and spirilli are shaped like spirals. Using shapes to describe bacteria helps scientists but bacteria into groups, which is often called classification.

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