What are cells?

Today, You’re going to learn about cells.

Wherever you look, there are living things, such as trees, birds, and flowers.

All living things have different sizes, shapes, and characteristics, but…

… they have one thing in common.

The commonality is that they are all made of cells.

Cells are basic units of all living things including human beings, like…

… a building brick of this Lego castle, or a brick of this house.

For example, dogs are made of cells and …

… so are all plants.

But nonliving things do not have cells.

Do you think you can see cells with your eyes? No. Cells are so tiny that you cannot see them with naked eyes.

You have to use a microscope to see cells.

As you can see, cells are not exactly the same in their shapes and structure.

At first glance these cells appear to have little in common other than the body or body part that houses them. For all their differences, though, different types of specialized cells have a lot in common. Even plant and animal cells have far more structural similarities than they have differences.

They are remarkably similar, as in these drawings.

There is one more thing you have to remember about cells.

New cells are produced from existing cells.

So when you grow,

it’s because your bone cells are making more bone cells, and …

… your skin cells are making more skin cells.

Line drawing of a cell Real image of a cell

Things to Remember! 1. Cells are basic units of all living things including human beings. 2. Cells are not exactly the same in their shape and structure, but remarkably similar. 3. New cells are produced from existing cells.

United Streaming  The Lives of Cells [19:38] Segments This video contains 10 segments Introduction: What Are Cells? [01:41] Bacteria [01:34] Protists [02:31] Multicelled Organisms [01:30] Cells Working Together [04:14] Review of Part One [01:03] The Five Basic Life Functions [01:42] The Parts of a Cell [02:15] Making New Cells [02:16] tId=44AA5AC6-CB75-40A DD4FD0900BC5&blnFromSearch=1&productcode=US tId=44AA5AC6-CB75-40A DD4FD0900BC5&blnFromSearch=1&productcode=US

Number your paper from 1 to 10 to answer these questions.

1. ________, which are very tiny, make up all living things.

2. Answer yes or no. Is this spider made up of cells?____________

3. True or False There are only two types of cells.

4. True or False Cells are not exactly the same in their shape and structure, but remarkably similar.

5. New cells are produced ___________. a. from food b. by dividing existing cells c. from dead cells d. from bacteria

6. All cells ___________ a. look exactly alike b. are red c. are the basic unit of structure in living things d. have the same parts

7. To see cells you ____. a. just look with your eyes b. use a magnifying glass c. must use a microscope

8. The smallest living thing found on Earth are _____. a. bacteria b. birds c. protists d. spiders

9. Which is larger? a. bacteria b. protists

10. Elephants have _____ cells. A. a few cells B. about a 100 cells C. billions of cells