Can you explain the discovery of cells?

What would make someone think that a rabbit or a tree or a person is

make up of tiny parts that cannot be seen?

Robert Hooke• Discovered cells in 1665• British• Wasn’t even looking for cells! He was trying to impress

other scientists.• Made a slide of Cork tree & looked at it with a simple

microscope.

The 1st Cell• Looked like 100’s of little boxes or honeycomb• Hooke named them cells, which means “little rooms” in

Latin.• Hooke thought

cells were only in

plants & fungi b/c

they have cell walls.

Anton van Leeuwenhoek• Dutch• 1673• 1st to look at pond scum, blood, plaque, bacteria, & bread

yeast.• Called the organism he saw animalcules which means

“little animals.”

Fish, birds, & frogs have oval shaped blood cells.

Humans & dogs have flatter blood cells.

Matthias Schleiden• German• 1838, 2 centuries later, realized that all living

things had cells by looking at plants.

“Hmmm…do all the parts of a plant have cells?”

Theodor Schwann

• 1839• German• Found that all animals have cells• Co-wrote the Cell Theory w/ Rudolf Virchow.

“Animals are full of cells!”

The Cell Theory

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

2. The cell is the basic unit of life in all living things.

3. All cells come from other cells (added 20 years later by Virchow).

I believe in cells!

Create a timeline with a short description on the history of the first

cell.

Can you describe the structures within every cell?

2 Types of Cells

Prokaryotic

Cells• No nucleus• No membrane covering

the organelles• Circular DNA• Bacteria

Eukaryotic

Cells• Nucleus• Membrane covering the

organelles• Linear DNA• Are all other cells

The Cell• Cells come in many shapes, sizes, & have

diff. functions.

Organelles

Cytoplasm

HereditaryMaterial

Cell Membrane

All Cells

Hereditary Material

• DNA- deoxyribonucleic acid• Controls all the cells activities • Contains the info. for making new cells.

Organelles

• The chemicals and structures that allow the cell to live, grow, and reproduce.

• They’re diff. for diff. cells.

http://www.cs.brown.edu/stc/outrea/greenhouse/nursery/biology/home.html

Cytoplasm

• The fluid that holds the organelles in a cell.

Cell Membrane

• Barrier between inside of the cell and the environ.

• Controls material passing thru the cell.

Surface-to-Volume Ratio

• A growing cell needs a large surface area to exchange material.

• As surface-to volume ratio decreases the cell’s size increases.

(# of cells increases but not the size of the cell.)

So, what’s so great about being multicellular?

1. Being made of 1 large cell would mean the outer surface would be too small to allow in the material you would need, so the cell would die.

Ex. This is why an elephant has cells the same size you do!

What else is great about being multi-cellular?

2. Cells can perform lots of diff. jobs! Which allow organisms to do lots of diff. things at the same time!

What functions is this organism

doing?

Now that you know what a basic cell looks like, draw and label some

of the basic parts.