1. Cells and Microorganisms1

2. Did you know that you and oak trees are both made of cells
Did you know that you and oak trees are both made of cells? A cell is a tiny part of a living thing. Your cells and the cells in oak trees are different from each other. Still, they may not be as different as you think. A plant cell actually has more parts than an animal cell. Both kinds of cells take in nutrients and get rid of wastes. This lesson will help you learn more about cells.
Let’s look at a plant cell up close!

3. Plant Cell Nucleus Vacuole Cytoplasm
1. Plant Cell: As you can see in this diagram, a plant cell is surrounded by a cell wall. This stiff wall protects the cell. The walls of plant cells stick to each other to give the plant its shape. Just inside the cell wall is the cell membrane, which is a thin membrane to allow 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.
Nucleus
2. The nucleus controls the cell’s growth. The plant’s genes are stored here.
Vacuole
Cytoplasm
4. The rest of the plant cell is filled with cytoplasm, which is much like jelly. Much of the cell’s work takes place here.
Cell membrane
Cell wall
3. The 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.
Chloroplast 3

4. Plant and Animals Cells
Plant Cell
Nucleus:
Located near the center of the cell – the plant’s genes are located here
Vacuole:
Stores food, water, or wastes
Cytoplasm:
Jelly-like substance that fills cell
Cell membrane:
Thin membrane allows water and nutrients to pass into the cell and allows wastes, including oxygen, to pass out of the cell
Chloroplast:
Produces food for the plant
Cell wall:
Protects and supports the plant 2

5. Animal Cell Cytoplasm: Nucleus: Cell membrane:
1. As you can see, animal cells have some of the same parts as plant cells. The cell membrane of an animal cell has the same job as it does in a plant cell. It also protects the cell from harmful substances. The nucleus controls the cell’s growth and contains genes. The nucleus is surrounded by cytoplasm.
2. Animal cells do not have cell walls. This is actually an advantage. With no cell walls, animal cells can take different shapes. They have developed in different ways. For example, 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.
Cytoplasm:
Jellylike substance that fills the cell
Nucleus:
Controls the cell’s growth and contains its genes
Cell membrane:
Allows materials to move in and out of the cell and protects cell from harmful substances

6. Plant and Animals Cells
Animal Cell
Muscle cells
Bone cells
Cytoplasm:
Jellylike substance that fills the cell
Nucleus:
Controls the cell’s growth and contains its genes
Liver cells
Cell membrane:
Allows materials to move in and out of the cell and protects cell from harmful substances 3 6

7. Cells
cell structure

8. F.Y.I.
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. This is not an advantage. As you know, animals cannot produce their own food. They must get their energy by eating plants, other animals, or both. Thus, 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!
Only the main parts of plant and animal cells are described here. Both kinds of cells contain many other parts. Some of these parts help the cell store and digest food. Some parts get rid of wastes. Some help the cell divide so the plant or animal can grow. Others pass genes from the cell to its offspring. All cells are like factories with many working parts.
Liver cells
bone cells
muscle cells
fat cells

9. A. Review Question 1 Which of these is NOT made of cells? A. a rock
B. an ant
C. moss
D. a stick A.

10. B. Review Question 2 Which part is NOT found in an animal cell?
A. cytoplasm
B. Cell wall
C. Cell membrane
D. nucleus B.

11. C. Review Question 3 Which 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.

12. B. 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.

13. Single Celled and Multi-Celled Organisms
Both plants and animals can be made of one cell or millions of cells like you. One-celled organisms, however, tend to be different from those with many cells. Some one-celled creatures have a nucleus, and some do not. Some single-celled plants have chloroplasts, but do not have stiff cell walls. All single-celled organisms eat, get rid of wastes, and reproduce.

14. Single Celled and Multi-Celled Organisms
Amoebas
Fox News Video Clip Brain Eating Amoeba Causes Death
Amoebas are single-celled or one-celled organisms.
Check out these amoebas eating!
Cytoplasm
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.

15. Single Celled and Multi-Celled Organisms
Algae
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.

16. 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. 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.
Bacteria

17. Review Question 1 A Which part does an amoeba NOT have? chloroplasts
cell membrane
cytoplasm
nucleus A

18. Review Question 2
Which of these produces most of the oxygen on Earth?
amoebas
bacteria
Algae
Multi-celled plants C

19. Review Question 3
How are single-celled algae different from multi-celled plants?
These algae do not have stiff cell wall.
These algae have no chloroplasts.
These algae have a nucleus.
These algae have a cell membrane. A

20. Review Question 4
How do you know that bacteria can reproduce easily?
They have no nucleus.
They number in the billions.
We need a microscope to see them.
They come in many shapes and sizes. B

21. Helpful and Harmful Microorganisms
A microorganism is a living thing that is too small to see without a microscope. Microorganisms include amoebas, algae, bacteria, and other tiny organisms. Some microorganisms help us in a number of ways, while others can make animals and plants sick. You will learn more about harmful and helpful microorganisms in the next few slides.

22. Harmful Microorganisms
Helpful and Harmful Microorganisms
Harmful Microorganisms
Salmonella
E. coli
Staph
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.
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. 22

23. Harmful Microorganisms
Helpful and Harmful Microorganisms
Harmful Microorganisms
A virus is another microorganism that causes diseases. A virus is 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.
Vomiting
Virus
AIDS Virus
Cold
Virus

24. Harmful Microorganisms
Helpful and Harmful Microorganisms
Harmful Microorganisms
Bakers yeast
A fungus is a microorganism, too. 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.
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.

25. Harmful Microorganisms
Helpful and Harmful Microorganisms
Harmful 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. They include athlete’s foot and ring worm (which is not really caused by a worm).
Even algae can be harmful. “Red tide” in a lake or ocean is caused by a kind of algae that grows very fast. It has nothing to do with tides. Some algae in a red tide contain poison that can kill fish. 10

26. Helpful Microorganisms
Helpful and Harmful Microorganisms
Helpful Microorganisms
You might be surprised to learn that we could not live without microorganisms. Without the algae and other tiny plants floating in the ocean, we would not have enough oxygen to stay alive. 11

27. Helpful Microorganisms
Helpful and Harmful Microorganisms
Helpful Microorganisms
Algae and other microscopic plants and animals, called plankton, 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. Thus, an important food source- fish – depends on microorganisms. 12

28. Helpful Microorganisms
Helpful and Harmful Microorganisms
Helpful Microorganisms
More Than Just Dirt! There are over four billion micro-organisms in a teaspoon of healthy soil.
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. 13

29. Helpful Microorganisms
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

30. Helpful Microorganisms
Helpful and Harmful Microorganisms
Helpful Microorganisms
Certain bacteria in our bodies helps digest our food.
Drug companies began producing penicillin in 1943, but only four years later, bacteria appeared that could resist it. New bacteria that can resist penicillin are still appearing.
Some medicines such as penicillin, which is made from mold and Streptomycin which is made from bacteria, help treat or cure many diseases.
Without microorganisms, we would have trouble eating any food. Certain bacteria in our bodies help digest food. As you can see, our survival depends on the helpful microorganisms in and around us!
Rotting wood
Microorganisms make dead things decay. Without them, the Earth would be covered with a very thick layer of dead plants and animals.

31. Getting Dirty with Microorganisms
Some microorganisms help remove harmful wastes from sewage at water treatment plants. Others help clean up oil spills.

32. B Review Question 1 How can mold be helpful?
It grows on bread and other food.
It helps dead plants decay.
It is a kind of fungus.
It grows on wheat plants. B

33. A Review Question 2 Which statement is true?
Microorganisms cause disease.
Microorganisms cure disease.
Some microorganisms are eaten.
Microorganisms are rare. A

34. A Review Question 3 Why are bacteria grouped with microorganisms?
Both cause diseases.
Both cure diseases.
Both are single-celled.
Both are harmful. A

35. D Review Question 4 How can you avoid touching microorganism?
Make sure your meat is well cooked.
Wash your hands thoroughly many times a day.
Do not touch any soil.
You can’t avoid touching microorganisms. D