EQ: How can a microorganism be both

harmful and beneficial?

Harmful and Beneficial

Microorganisms

What is a microorganism?

A microorganism is an organism that can be seen only with the

aid of a microscope.

They include bacteria, protozoans, algae, and fungi.

Beneficial microorganisms produce a favorable result. They are

helpful and useful.

Harmful microorganisms (pathogens) are likely to have a

damaging result. They are also called pathogens or

“germs.” (p. 363)

Bacteria—Harmful or Beneficial? Both!

Read about Bacteria on page 93.

(Also can be “Harmless”.)

Both!

Read about Fungi on page 95, and on page 364.

(Also can be “Harmless”.)

A fungus (fungi is the plural) is neither a plant nor an animal.

Fungi—Harmful or Beneficial?

Beneficial Bacteria: Hidden Helpers in

our Body- p. 93

Billions of bacteria in our bodies live in our intestines—more

than 100 different kinds! (There is enough bacteria in you to

fill three coffee cups!)

These bacteria help us digest our food to get nutrients.

Other bacteria make vitamins to help keep us healthy and

disease-free.

Yummy Food…“Thank you, Microorganisms.”

Bacteria that is put in milk changes the

milk to be thicker and slightly sour.

Yogurt bacteria helps our bodies get

more nutrients from other foods we

eat. (p. 93)

Yeast in bread is what helps it to rise.

Yeast is a fungus. (p. 95)

Mold, another type of fungus, helps to

flavor the different kinds of cheeses we

eat.

Medicine… “Thank you, Microorganisms.”

Some microorganisms are used to make medicines to fight off

harmful microorganisms.

We will learn more about this in a bit…

Harmful Microorganisms (Pathogens):

Bacteria on your teeth

Bacteria live in your mouth.

They like to feed on old food stuck in your teeth.

As they feed, they make an acid that makes teeth soft and

decay. This causes cavities (holes in your teeth).

Their favorite foods are sweet, sugary foods.

This is why brushing your teeth is so important!!

WANT A JOKE?

A mushroom looks up at a kid playing soccer. He asks, “Hey,

can I play?”

The kid says, “Nope.”

The mushroom replies, “Why not? I’m a Fungi.”

Harmful Microorganisms (Pathogens):

Fungi (p. 364)

Fungi are related to mushrooms, but the kind that we get on

our skin is a type of pathogen. (It’s like mold for people.)

Rashes like ringworm and athlete’s foot are fungi that can live

and grow on our skin.

The rashes are red and itchy and can be treated by an anti-

fungal cream from the doctor.

Pathogen: Mold (p. 95)

Some mold can be beneficial microorganisms (like the ones

that make cheese), but some types of mold are also harmful

and will make you sick if you eat them.

Mold is also a fungus.

Leave out a piece of bread… watch how quickly mold will

grow on the bread.

Pathogen: Protozoans (p. 364)

Protozoans can live in unpurified water (like ponds, streams,

and creeks) and drinking unclean water can cause a person to

become very ill.

Also, a tropical disease called malaria is caused by a

protozoan that has infected a mosquito which in turn bites a

human and infects that person.

Many people that live in places that have the threat of malaria

sleep with mosquito nets around their bed for protection.

Pathogen: Virus (p. 365)

Viruses are the smallest known pathogens, but are not considered true living organisms due to the fact that they do not have their own cells.

Viruses need to infect other cells to move and duplicate.

They get into our bodies on food, through cuts on the skin, or by breathing them in through the air. Some examples of viruses are colds, the flu, chickenpox, and warts.

To help our bodies fight off viruses, we get shots called vaccinations (vaccines).

Vaccines put a small amount of the pathogen into our bodies so our bodies get used to fighting it off. (p. 376)

(One million viruses could fit on theperiod at the end of one of yoursentences on your paper.)

Spreading Pathogens: Airborne and Contact Some pathogens can enter our body when we breathe. They can

get into the nose, mouth, throat, and chest.

Other pathogens float in the air and land on us.

When on our skin, they can then enter through sores or wounds on the body.

Some pathogens on our hands can transfer to food when we handle it to eat it.

Lastly, if you come in contact with a sick person or touch somewhere that a sick person has been, you might could catch a pathogen as well.

This is why covering your mouth when you sneeze and washing your hands is SO IMPORTANT!!

The Immune System (p. 374-376) God made our body to fight off diseases!

Your body makes special cells called white blood cells to keep your body protected from dangerous pathogens.

They release special proteins called antibodies to kill the pathogen and prevent it from spreading.

After that, your body stores information about that pathogen in special memory cells so your body can more easily fight it off again at a later time.

You then build up immunity to that pathogen!

Medicine… “Thank you, Microorganisms.”

(p.377) To help our immune system fight diseases,

antibiotics are made from microorganisms.

In laboratories, bacteria and fungi are grown in large tanks called bio-vats.

In these bio-vats, the microorganisms float, grow, and feed in a watery liquid. When necessary, some of the liquid is taken from the tanks and medicine is made.

Medicines made from these are called antibiotics.

Antibiotics can fight bacterial and fungal infections. (not viral infections)

One example of an antibiotic is penicillin, which is made from mold (a fungus).