Cells and

Microorganisms

1

Wonder Wall: What questions do you have about cells and microorganisms?

Lesson 1

Do You Know the Differences Between a Plant and an Animal

Cell?Discuss this with a neighbor and be prepared to share your answers with the class.

Why do you need to know this? See next

slide…

Georgia Performance Standards• S5L3. Students will diagram and label parts of various cells

(plant, animal, single-celled, multi-celled). • a. Use magnifiers such as microscopes or hand lenses to

observe cells and their structure. • b. Identify parts of a plant cell (membrane, wall, cytoplasm,

nucleus, chloroplasts) and of an animal cell (membrane, cytoplasm, and nucleus) and determine the function of the parts.

• c. Explain how cells in multi-celled organisms are similar and different in structure and function to single-celled organisms.

• S5L4. Students will relate how microorganisms benefit or harm larger organisms.

• a. Identify beneficial microorganisms and explain why they are beneficial.

• b. Identify harmful microorganisms and explain why they are harmful.

Did you know that you and oak trees are both made of cells? A cell is a tiny part of a living thing.

• Are we like plants? How are plant cells and animal cells alike?

• Plant cells have more parts than an animal cells

• BUT- both kinds of cells take in nutrients and get rid of wastes.

• Reading Connection: What kind of text structure would best represent the information?

Let’s look at a plant cell up close!

Cell Form and Function

Plant Cell•The plant cell is surrounded by a cell wall.

This stiff wall protects the cell. •Why do you think plants need stiff walls?• Just inside the cell wall is the cell membrane• This thin membrane allows water and

nutrients to pass into the cell.• It allows wastes, including oxygen, to pass

out of the cell. •The cell membrane stops some materials

from entering the cell and injuring it.•Look at the next slide for an illustration.

Plant Cell

Cell wall

Cell membrane

Nucleus

Chloroplast

Cytoplasm

Vacuole

The nucleus controls the cell’s growth. The plant’s genes are stored here.

Green chloroplasts produce food for the plant. The chloroplasts combine sunlight, water, and carbon dioxide from the air to produce sugars, which give the plant energy to grow and bloom.

The rest of the plant cell is filled with cytoplasm, which is much like jelly. Much of the cell’s work takes place here.

Plant CellsPlant Cell- Can you identify the parts?

???: Protects and supports the plant

???:Thin membrane allows water and nutrients to pass into the cell and allows wastes, including oxygen, to pass out of the cell

???:Located near the center of the cell – the plant’s genes are located here

???:Produces food for the plant

???:Jelly-like substance that fills cell

???:Stores food, water, or wastes

2

Do plant and animal cells have the same parts?

• Cell membrane – has same job in both cells

• Also protects the cell from harmful substances.

• The nucleus controls the cell’s growth and contains genes.

• The nucleus is surrounded by cytoplasm

• What is cytoplasm?

• See next slide for an illustration

Animal Cell

Animal Cell

Nucleus:Controls the cell’s growth and contains its genesCell membrane:Allows materials to move in and out of the cell and protects cell from harmful substances

Cytoplasm:Jellylike substance that fills the cell

• Why don’t animal cells have cell walls?

• With no cell walls, animal cells can take different shapes and can develop in different ways

• Animal cells can become nerve cells, muscle cells, blood cells, and so on. Having different kinds of cells has allowed animals to develop muscles, bones, and nerves have given animals the ability to move from place to place.

Animals CellsAnimal Cell- CAN YOU IDENTIFY THE PARTS?

???:Controls the cell’s growth and contains its genes

???:Allows materials to move in and out of the cell and protects cell from harmful substances

???:Jellylike substance that fills the cell

Liver cells

Muscle cellsBone cells

Cells cell structure

The illustrations below show some of the shapes that animal cells can take. On the other hand, most plant cells have square shapes. Their stiff cell walls prevent that shape from changing. However, the cell walls do serve as the plant’s “skeleton”. They support the plant.

• Animal cells do not have chloroplasts. Animals cannot produce their own food, so they don’t need them! They must get their energy by eating plants, other animals, or both. Animals must depend on plants and animals that they eat to survive.

• Animal cells tend to be smaller than plant cells. However, you will need a microscope to see either one. The largest plant cell is only about 100 micrometers wide. A micrometer is 1/1,000,000 meter (1/25,000 inch). That’s tiny!

Liver cells

bone cells muscle cells

fat cells

Reading connection: What clue words let you know that the author is showing you a contrast (differences) in the two cells?

Animal Cell - Functions

Nucleus control center of the cell – stores information for cell functions

Cytoplasm jelly-like substance where cell activities take place

Cell membrane thin, controls the substances that enter or exit the cells

Let’s summarize:

Nucleus control center of the cell – stores information for cell functions

Chloroplasts contain green pigment chlorophyll, needed in photosynthesis

Cytoplasm jelly-like, where cell activities take place

Cell membrane thin, controls the substances that enter or exit the cells

Cell wall stiff wall which gives plant cells their shape

Plant Cell - Functions

Let’s summarize:

What are the Differences Between Plant Cells and Animal Cells? Tell

your neighbor.

Plant Cell Animal Cell•Plant cells contain chloroplasts to make food from solar energy during photosynthesis.

•Animal cells DO NOT contain chloroplasts.

•Plant cells contain cell walls.

Animal cells DO NOT have cell walls.

Review Question 1

Which of these is NOT made of cells?A. a rockB. an antC. mossD. a stick A.

Review Question 2

Which part is NOT found in an animal cell?A. cytoplasmB. Cell wallC. Cell membraneD. nucleus B.

Review Question 3Which statement is true?A. The nucleus gives the cell its shape.B. Plant cells are filled with jelly-like

chloroplasts.C. An animal cell can become a bone cell.D. A plant cell can become a nerve cell.

C.

Review Question 4

Which statement is true?A. The cell wall allows materials to pass in and out of

cells.B. Both plant and animal cells have a cell membrane.C. The genes for plant cells are in the cytoplasm.D. A plant cell produces food in its nucleus.

B.

• Both plants and animals-made of one cell or millions of cells like you.

• One-celled organisms are different…

• Some one-celled creatures have a nucleus; some don’t. Some single-celled plants have chloroplasts, but do not have stiff cell walls.

• All single-celled organisms eat, get rid of wastes, and reproduce.

Lesson 2: Single Celled and Multi-Celled Organisms

Single Celled and Multi-Celled Organisms

Single Celled and Multi-Celled OrganismsAmoebas

Amoebas are a kind of animal. They live just about anywhere! You can find them in pond water, saltwater, moist soil, and in animals… including you!!!!!!!!!!!!!! Notice that their cell structure is a lot like yours. • The amoeba “breathes” when oxygen passes through the

cell membrane into the cytoplasm. • Carbon Dioxide passes out of the amoeba through the same

membrane. This cell “eats” by surrounding a bit of food, such as bacteria, and sweeping it inside.

Cytoplasm

Amoebas are single-celled or one-celled organisms.

Check out these amoebas eating!

Fox News Video Clip Brain Eating Amoeba Causes Death

Single Celled and Multi-Celled OrganismsAlgae

• Algae are like plants. • They live in the water and other moist places. Some algae have only

one cell. • That includes the billions of algae that float on the surface of the

ocean. • Seaweed is a form of algae that has many cells. Some seaweed

stretches 100 meters (300 ft) from the ocean floor to the surface. • Algae are among the oldest living things on Earth. They have a cell

membrane, cytoplasm, and a nucleus. They are not surrounded by a stiff cell wall, but they do contain chloroplasts to make food for themselves. Algae produces much of the oxygen in the air you breathe. In fact, algae produces more oxygen than all the other plants combined.

AlgaeSingle Celled and Multi-Celled Organisms

• They have a cell membrane, cytoplasm, and a nucleus.

• They are not surrounded by a stiff cell wall, but they do contain chloroplasts to make food for themselves.

• Algae produces much of the oxygen in the air you breathe.

• In fact, algae produces more oxygen than all the other plants combined.

Single Celled and Multi-Celled Organisms

Bacteria• Bacteria are one-celled organisms. • We did not even realize that they exist until

the microscope was invented in the 1600s. • There are more bacteria than any other kind

of living thing. • A handful of soil can contain billions of

bacteria. • Bacteria have NO nucleus. • The material that is in the nucleus of other

cells is spread throughout the cytoplasm in bacteria.

Bacteria

Bacteria

• They are the oldest form of life on Earth. • They live EVERYWHERE on Earth from

the Arctic to the bottom of the ocean. • Some bacteria are helpful and some are

harmful.• You’ll learn more about the different types

of bacteria in the next slides.

Review Question 1

Which part does an amoeba NOT have?A. chloroplastsB. cell membraneC. cytoplasmD. nucleus A

Review Question 2

Which of these produces most of the oxygen on Earth?

A. amoebasB. bacteriaC. AlgaeD. Multi-celled plants

C

Review Question 3How are single-celled algae different from multi-

celled plants?A. These algae do not have stiff cell wall.B. These algae have no chloroplasts.C. These algae have a nucleus.D. These algae have a cell membrane.

A

Review Question 4How do you know that bacteria can reproduce

easily?A. They have no nucleus.B. They number in the billions.C. We need a microscope to see them.D. They come in many shapes and sizes.

B

Let’s Review!

What are cells? Plant vs. AnimalSingle-Celled and Multi-Celled Organisms

Discuss these with a neighbor.Are there more single-celled (or one-celled) organisms or multi-celled organisms? What

are we???Discuss types of single-celled organisms we

have learned about.

Lesson 3: Helpful and Harmful Microorganisms

A microorganism is a living thing that is too small to see without a microscope. What else is too small to be seen without a microscope?Microorganisms include amoebas, algae, bacteria, and other tiny organisms. Do you remember the importance of bacteria and algae and why they are known for?Some microorganisms help, while others can make animals and plants sick. Can you figure out why???

Helpful and Harmful MicroorganismsHarmful Microorganisms

• Some harmful bacteria, such as Salmonella and E. coli, can make you very sick.

• These bacteria are found on raw chicken and other meat, raw eggs, and other foods. If foods with bacteria on them touch other foods, such as lettuce, the bacteria can spread to the lettuce.

• Cooking kills these bacteria. • However, if cooked food is left out of the refrigerator for 2 hours or

longer, harmful bacteria will start to grow on it.

E. coliSalmonella

Staph

Helpful and Harmful MicroorganismsHarmful Microorganisms

• You probably have staph bacteria on your skin right now!• It can cause serious infections of the blood, bones, and

lungs. • Have you ever had Strep throat? • It was caused by strep bacteria and can lead to serious

diseases. • Strep Bacteria can harm newborn babies, pregnant

women, older adults, and adults who have certain other illnesses.

E. coliSalmonella

Staph

Helpful and Harmful MicroorganismsHarmful Microorganisms

Vomiting Virus

AIDS Virus

Cold Virus

• A virus is another microorganism that causes diseases.

• Even smaller than bacteria

• It must use a living cell to grow and reproduce.

• Viruses cause many diseases, from colds to AIDS.

• Viruses often change as they reproduce.

• A medicine that killed the first virus often cannot kill the changed virus.

Helpful and Harmful Microorganisms

Harmful Microorganisms

• A fungus is a microorganism (the plural of fungus is fungi)• Like plants, fungi cannot move around• Like animals, fungi cannot make their own food• They get their energy by eating other living or dead

organisms.

Bakers yeast

Helpful and Harmful Microorganisms

Harmful Microorganisms

• Kinds of fungi include molds, yeasts, and mushrooms. • Some kinds of fungi, such as yeast, contain only one cell.

Others, such as mushrooms, are multi-celled. • You have probably seen mold growing on food. • Each bit of mold is very small, but when mold grows in

large groups, you can see it.

Bakers yeast

Helpful and Harmful MicroorganismsHarmful Microorganisms

• Harmful mold and other fungi can spread through crops and kill them.

• They can also rot food and wood. • Fungi cause several skin diseases-including athlete’s foot

and ring worm (which is not really caused by a worm).10

Helpful and Harmful MicroorganismsHarmful Microorganisms

• What does algae give us, and why is it important? • Even algae can be harmful. “Red tide” in a lake or ocean is

caused by a kind of algae that grows very fast (has nothing to do with tides, though)

• Some algae in a red tide contain poison that can kill fish.10

Harmful Microorganisms

Helpful and Harmful MicroorganismsHelpful Microorganisms

• We CANNOT LIVE without microorganisms.

• Without the algae and other tiny plants floating in the ocean, we would not have enough oxygen to stay alive.

Tell your neighbor why…

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Helpful and Harmful MicroorganismsHelpful Microorganisms

• Algae and other plankton (microscopic plants and animals) float on the surface of the ocean.

• Tiny fish eat the plankton. Then larger fish eat the tiny fish.

• In time, people eat the larger fish. So… an important food source- fish – depends on microorganisms! Get it?

• Review some helpful microorganisms with your neighbor. 12

How can you use context clues to help you with an unfamiliar word on this slide?

Helpful and Harmful MicroorganismsHelpful Microorganisms

• Microorganisms also help plants grow on land. • Certain fungi help plants take up nutrients from the soil. • Without these nutrients, the plants would not grow as well. • That would mean less food for us and other animals. • HOW? 13

Helpful and Harmful MicroorganismsHelpful Microorganisms

More Than Just Dirt!There are over four billionmicroorganisms in a teaspoon of healthy soil. 13

Helpful and Harmful Microorganisms

Helpful Microorganisms • Microorganisms help

provide us with other kinds of food.

• Bacteria turn milk into yogurt.

• In fact, one gram of yogurt can contain up to 1 billion bacteria. (It’s supposed to!)

• Bacteria also help produce certain kinds of cheese. Yeast makes bread, rolls, and cakes rise. 14

Helpful and Harmful MicroorganismsHelpful Microorganisms

Certain bacteria in our bodies helps digest our food.

Some medicines such as penicillin (which is made from mold) and Streptomycin (which is made from bacteria), help treat or cure many diseases.

Drug companies began producing penicillin in 1943, but only four years later, bacteria appeared that could resist it (fight it off). New bacteria that can resist penicillin are still appearing. Scary, huh?

Helpful and Harmful MicroorganismsHelpful Microorganisms

• Microorganisms make dead things decay.

• Without them, the Earth would be covered with a very thick layer of dead plants and animals. YUK!Rotting wood

• Without microorganisms, we would have trouble eating any food.

• Certain bacteria in our bodies help digest food. • Our survival depends on the helpful microorganisms in

and around us!• Discuss the many ways that we depend on helpful

microorganisms with a neighbor.

Helpful Microorganisms

• Some microorganisms help remove harmful wastes from sewage at water treatment plants.

• Others help clean up oil spills.

Review Question 1

How can mold be helpful?A. It grows on bread and other food.B. It helps dead plants decay.C. It is a kind of fungus.D. It grows on wheat plants.

B

Review Question 2

Which statement is true?A. Microorganisms cause disease.B. Microorganisms cure disease.C. Some microorganisms are eaten.D. Microorganisms are rare.

A

Review Question 3

Why are bacteria grouped with microorganisms?A. Both cause diseases.B. Both cure diseases.C. Both are single-celled.D. Both are harmful.

A

Review Question 4

How can you avoid touching microorganism?A. Make sure your meat is well cooked.B. Wash your hands thoroughly many times a day.C. Do not touch any soil.D. You can’t avoid touching microorganisms.

D