LESSON #1What is so extraordinary about the organizationof living organisms?

DISCOVERING THE

CELL

The unit of life

Levels of

biological

organizatio

n

Before the 1800s

How were cells discovered?

Discovering the principles of the

microscope

In 1590, Zacharias

Janssen, a Dutch

eyeglass maker.

2 overlapped lenses

increase magnification

Anton Van Leewenhoek (1632-

1723)

Father of microbiology

First to observe living

organisms smaller than

what the human eye can

see.

Robert Hooke

Scientist

Made an improved

microscope.

First used the word

“cell” to indicate what

living beings are made

of.

What Hooke saw…

A pause

In the following

years Hooke’s

discovery didn’t

have much influence

in science.

S. XVII y XVIII

Scientists were

focused on

classifying new

species discovered

by explorers.

In the early 19th Century they had a revolutionary idea in Germany.

Living things are

made of living

units

They started studying plants and animals at a microscopic level again.

Both came up with a theory that said that all organisms come from a cell and

develop from there by the formation of new cells. CELL THEORY.

18381839

All living things are formed by one or more

cells

A cell is the smallest and simplest living

thing.

All cells come from other pre-existing cells.

All cells can function independently,

although they work together in a coordnated

way when part of an organism.

One cell can perform all living functions : nutrition,

reproduction and interrelation

How large are things really?

Microscopic objectsare meassured in:

μm = 10-3 mm

Nm = 10-6 mm

Not visible with a naked eye.

Eye resolution is 0,2 mm

If two objects are separated by a smaller distance, wewill see them as one.

Exercise 1:

If an object meassures1 mm, how manymicrometers does itmeassure? And howmany nanometers?

Exercise 2

Paramecium caudatum magnified 300 times

3.6 cm

What is the size of the

paramecium?

Could we see it with

our naked eye?

20th Century interest: The cell

1930 invention of

the Electron

Microscope:

uses electrons

instead of light.

Resolution 0,5 nm.

Allows to see cells in

detail.

Electron Microscope Images

What do you think this is? And this?