A CELL is the smallest unit that can carry on all the

PROCESSES of life.

Every LIVING thing is made up of ONE or more cells.

A living thing that is made up of ONE cell is called

UNICELLULAR.

A living thing that is made up of MORE than one cell is

a MULTICELLULAR

organism.

How many cells are there in a human body?

•Between 50 to 100 trillion depending on a person’s size!

How many bacterial cells are there in and on a human body?

• 182 species of bacteria colonize the average person's skin

• There are about 1,000,000 bacteria per square inch on human skin

• Saliva may contain up to 1,000,000,000 bacteria per milliliter

• We have more bacteria living in and on us than cells in our bodies!

• Only about 10% of the cells in our bodies are Human!

Summary

Cells were first discovered in 1665

by the English scientist

ROBERT HOOKE.

Hooke cut a piece of CORK and observed it with a

microscope.

He sectioned other specimens and saw that they were all made up of ”LITTLE BOXES,” or cells, which reminded him of the little rooms

MONKS of that time lived in.

The first person to view LIVING cells was

Anton VAN LEEUWENHOEKIn 1675

I’m Anto

n

It took another 150 years for scientists to take the

work ofHOOKE and

VAN LEEUWENHOEK, And devise a unified

theory of cells.

In 1838 a GERMAN botanist, Matthias

SCHLEIDEN concluded that all plants were COMPOSED of cells.

In 1855 a German PHYSICIAN, Rudolph

VIRCHOW determined that cells only come from other CELLS.

The observations of these three scientists are

known as CELL THEORY

1. All living things are COMPOSED of one or more

CELLS.

2. Cells are organisms BASIC UNITS of structure

and function.

3. Cells come only from OTHER cells.

Cells vary greatly in SIZE, SHAPE, and internal

ORGANIZATION.

SizeCells must maintain a

SMALL size or else their surface area becomes

too SMALL to maintain all life functions.

ShapeMost cells are SPHERICAL or CUBOIDAL. They can also be FLAT like skin

cells, have long extensions like NERVE cells, or may have

the ability to change SHAPE like white BLOOD

cells.

Internal OrganizationCells differ in their internal

organization.

Cells that contain a NUCLEUS and membrane bound ORGANELLES are

called EUKARYOTES.Examples:

PLANT & ANIMAL cells

Cells that lack a NUCLEUS and

membrane BOUND organelles are called

PROKARYOTES.Example:

BACTERIA CELLS

Summary

Cell MembraneIs the structure that SEPARATES the cell

from its external environment.

Cell MembraneAllows some molecules to

PERMEATE, or pass through it, and acts as a

barrier to keep some MOLECULES out of the

cell. For this reason it is called a

SEMIPERMEABLEmembrane.

The Fluid MOSAIC Model of cell membranes

reveals that they are made up of a

LIPID bilayer.

It is like a fluid lipid sandwich with the Hydrophilic heads

pointing OUTWARD and the hydrophobic tails

pointing inward. The cell membrane also has

proteins embedded in it that can move around.

Is the JELLYLIKE material found inside the cell

membrane and is made up of WATER, salts, and organic molecules.

It is in constant motion called

CYTOPLASMIC streaming. The cytoplasm surrounds

“little organs” orORGANELLES

which each have a specific job.

Are the organelles where PROTEINS are made and are the most NUMEROUS

of the organelles.

(ER) is a membrane system of folded SACS and tunnels. There are two kinds of ER.

(rER) is studded withRIBOSOMES. Is abundant in

cells that export a lot of proteins or ENZYMES like the

pancreas.

(sER) has no RIBOSOMESAnd is like a highway for

molecules to move around the cell and as a STORAGE

area.

Is the processing, PACKAGING, and secreting

organelle of the cell. It is like a factory where a product is

ASSEMBLED at one end, packaged, then put into a

mail bag for delivery at the other end.

Are the POWERHOUSES of the cell that process and release ENERGY from the nutrients that enter the

cell.

They have CRISTAE which make more surface area for cellular respiration to

take place, and ATP is formed here. Cells that use a lot of energy like muscle cells have many

mitochondria. Mitochondria have

their own DNA.

Are the garbage men of the cell and contain

DIGESTIVE enzymes that break down wastes.

Provide a frame for the cell called the

CYTOSKELETON.They also help move things

around in the cell.

Are used in MOVEMENT and extend out from

the surface of the cell.Cilia are short and hairlike.

They beat in WAVES. Flagella are long and

whiplike, occur SINGLY or in pairs.

Directs the ACTIVITIES of the cell. It is surrounded by a NUCLEAR membrane that has holes in it

where molecules can enter and EXIT.

The nucleus contains CHROMATIN, strands of

DNA and proteins. When it condenses, it forms CHROMOSOMES, the

genetic information of the cell.

The NUCLEOLUS is a spherical body in the

nucleus where ribosomes are made.

Summary

Plant cells differ from ANIMAL cells because they

have a cell WALL that surrounds the cell

MEMBRANE. This helps support and protect the

cell. They also have sacs called VACUOLES and

plastids which store food or pigments.

Contain a green pigment called

CHLOROPHYLL that is used in

photosynthesis.

Contain pigments like orange CAROTENES, and yellow XANTHOPHYLLS, and red pigments. They

give plants their distinctive colors.

Store food such as STARCHES,

proteins, and lipids. They are

storage organs in potato TUBERS.