THE CELL THEORY

What is a theory? What is a cell.

When scientists agree upon an observation or idea, after repeated experimentation, they call it a theory.

There is so much

evidence most scientists accept it.

A cell is the basic unit of structure and function in living things.

This means that cells form the parts of an organism and carry out all of an organisms processes or functions

Robert Hook 1665

• One of the first people to observe cells.•Built his own compound microscope.•Observed Cork and found tiny rectangles he called “Cells.”

Anton van Leeuwenhoek 1674

With his simple microscope, made with a tiny glass bead for a lens, Leeuwenhoek looked at drops of water, scrapings from teeth and gums, and water from rain gutters. He found a variety of one-celled organisms.

Formulation of the Cell Theory

3 German Scientists are credited.

1. Matthias Schleiden- plants are made of cells.

2. Theodor Schwann- all animals made of cells.

3. Rudolf Virchow- a cell came from a cell that already existed.

The Cell Theory

1. All organisms are made up of one or more cells.

2. Cell is the basic unit of structure and function.

3. All cells come from pre-existing cells.

1. All organisms are made up of one or more cells. A cell is the

smallest unit of an organism that carries on the functions of life.

Cells are divided into two groups

1.Prokaryotic cells2.Eukaryotic cells

2. Cell is the basic unit of structure and function

Cells are building blocks of living organisms

All cells have the same basic parts to do specific tasks,

1. Take in nutrients2. Store3. Reproduce4. Breakdown substances5. Take in and use energy

3. Cells come from pre-existing cells. Because cells

come from other cells, scientists can study cells to learn about growth an reproduction.

Two methods of reproduction:

1. Meiosis2. Mitosis

Organisms are divided into two groups.

1. Prokaryote are single-celled organisms, and are divided into two groups.2. Eukaryotes are multi-celled organisms.

Prokararyotic Vs Eucaryotic cells-

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Organisms are classified into three domains. Bacteria ,Archaea, and Eucaryota. Bacteria and Archaea are Prokaryotes . Eucaryota are Eucaryotes .

Prokaryotic: Single Celled Organisms

Archaebacteria

These organisms lived in extreme environments - deep sea hydrothermal vents, "black smokers", hot springs, the Dead Sea, acid lakes, salt evaporation ponds –

Archaea are found in the harshest environments on Earth, and are the oldest known organisms on Earth, appearing in the fossil record over 3.6 BILLION years ago.

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Prokaryotic: Single Celled Organisms

Bacteria: StreptococcusBotulism and Staphyloccus(skin boils), and EColi

Example: Cyanobacteria are aquatic and photosynthetic, that is, they live in the water, and can manufacture their own food using photosynthesis.

Prokaryotic cells-

Prokararyotic cells- Found only in

single-celled organisms such as Paramecium and bacteria.

Does not have membrane bound structures inside the cell.

No nucleus

Eukaryotic Cells

Eukaryotic Cells-

Cells with membrane-bound structures inside the cell.

Found in multi-celled organisms.

Cells contain a nucleus

Organisms composed of many cells.

Plants Animals Molds Fungi

Organization of Cells in Multi-Celled Organisms

1. Cell- The smallest unit that has properties of life.

2. Tissue- Group of similar cells that work together to do one job. Ex: Heart tissue

3. Organs- two or more types of tissue that work together. Ex: Heart: nerve, blood, and cardiac muscle tissue.

4. Organ Systems – A group of organs working together to perform a certain function. Ex: Cardiovascular system includes heart, arteries, veins, and capillaries. 5. Organisms- Many organ systems that work together

Ex: Humans

Different cells perform different functions in multi-celled organisms.

Plant • leaves - epidermis cells- protect the

plant.• Trunks of trees- xylem cells- extra

thick cell walls.

Humans–Nerve cells – carry messages to and from

different parts of the body–Blood cells carry oxygen to and from

different parts of the body

Cells Are Different For A Reason

Depends On Their Job.

Size and Shape

Nerve Cells – are long to cover a large area.

Muscles cells- thin and long, in order to expand and contract

Why are cells different?

What about small blood cells and their flexible layer that surrounds the cell?

What about plants rigid cell wall surrounding them?

Basic Unit of Life and Structure

Ultimately Cells…… Take in nutrients and convert it to

energy Sized and shaped differently

according to their job- (function). Perform different jobs depending on

the needs of the cell Work together to maintain the life of

an organism.

The Cell Theory

1. All living things are made up of cells.

2. Cell is the basic unit of structure and function.

3. All cells come from pre-existing cells.