The Cell

Definition of Cellnote: only write down text in red

A cell is the smallest unit that is capable of performing life

functions.

Cell Theory

• All living things are made of cells. • Cells are the smallest living units. • All cells come from preexisting cells

through cell division.

Who came up with this theory?

1. Robert Hooke(1665)First person to see cells, he was looking

At cork and noted that he saw many boxes

That look like prison cells

Let’s call these things

cells!

Who came up with this theory?

2. Schleiden (1838)All plants are made of cells!

Onion skin cells

3. Schwann - 1839

Who came up with this theory?All animals are made of cells!

Human red blood cells

Who came up with this theory?

4. Virchow - 1855

All cells come from

pre-existing cells!

Examples of Cells

Amoeba Proteus

Plant Stem

Red Blood Cell

Nerve Cell

Bacteria

How big are cells?

• Mostly Microscopic

• Measured in microns (µm)

• A µm is one millionth of a meter!

How big are cells?

• Bacteria (aka E.coli)• Size=1 µm by 3 µm

How big are cells?

• Human red blood cell = 8 µm

How big are cells?

• Largest cell on the human body is the ovum

• 1000 µm in diameter

(1 mm)

Two Types of Cells

•Prokaryotic•Eukaryotic

Prokaryotic

• Do not have organelles surrounded by membranes

• Few internal structures

• Example: Bacteria

Eukaryotic• Contain organelles surrounded by membranes• Most living organisms are eukaryotes

Plant Animal

“Typical” Animal Cell

“Typical” Plant Cell