In your journal, create a 3 column KWL chart. Take a minute to record what you already know about cells and what you would like to know.

What is a cell?

A cell is the very smallest unit of living matter. All living things including plants and animals are made up of cells.

What is a cell made of?

Cells are made of atoms, which are the smallest units of matter.

How many different types of cells are there?

There are many different kinds of cells. The two

kinds you may already be familiar with are animal

and plant cells.

What makes plant cells different from

animal cells?One main difference is that plant cells contain

chloroplasts which contain chlorophyll.

What different organelles make up an

animal cell?Cells are tiny, but they have

lots of important parts

inside!

What different organelles make up an animal cell?

One part found in all cells is the cell

membrane. The cell membrane

surrounds the cell, holds the other

parts of the cell in place, and protects

the cell.

Inside the membrane, all cells, except for bacterial cells, contain a nucleus and

cytoplasm. The nucleus is a dark structure located in the middle of the cell. It controls the cell's activities, and acts like the cell's

brain. Inside the nucleus there is DNA which contains genetic information.

The cytoplasm is a jelly-like substance inside the cell where most of the cell's

activities take place. It's made out of water and other chemicals. All cell parts, except the nucleus, are located in the cytoplasm

Like all living things, cells die. If you watched a clock for one minute, about

three billion cells in your body die. The length of time cells live can vary. For example, white blood cells only

live for thirteen days, red blood cells live for about one hundred and twenty

days, liver cells live about eighteen months, and nerve cells can live up to one hundred years. That is a very big

difference!

Basically, each cell is made from an already existing cell. New cells

are made through a process called cell

division or mitosis. One cell turns into two cells and then each of those two cells turn into four cells, etc. Even humans

started life with only one cell.

How do I get new cells when the old ones die?

Most of the cells in multi-celled organisms use mitosis to reproduce. The animation shows the basic steps in mitosis which are:1) At the start of mitosis chromosomes are in the nucleus.2) The chromosomes in the nucleus will then make a copy of themselves3) Next the cell divides.4) Lastly, one set of chromosomes goes to the new cell and one set remains in the parent cell.

How do I get new cells when the old ones die?

Organisms like humans are made up of trillions of cells. There are also one celled organisms such as euglenas,

amoebas, and bacteria.

One of the most important tools that scientists use to study cells is

the microscope. An optical microscope can magnify a cell up to two thousand times. If an ant were

to be magnified at two hundred thousand times, it would be more than two and one half miles (four

kilometers) long. Scientists also put dyes in cells to make certain parts look bright under a microscope.

If cells are so tiny, how do scientists study them?

Do all cells inside me look the same?

No, different cells have different jobs. Cells with different jobs can

look very different.All cells start as stem cells.

Once they are ‘assigned’

a job, they change to fit

their purpose.

Skin Cells Nerve Cells

Blood Cells

Cancer is caused by cells that don’t duplicate correctly. Cells in our

immune system will try to kill the bad cells.Immune Cells

Attack Cancer Cell

Update your KWL chart with some new information that you

have learned about cells.