Cell Theory

THE CELL THEORY GREW

OUT OF THE WORK OF

MANY SCIENTISTS AND

IMPROVEMENTS IN THE

MICROSCOPE.

Many scientists

contributed to

the cell theory.

ROBERT HOOKE He was the first person to look at cells and

named them. He looked at cork cells which

are not living.

It is the bark of a tree so they are dead

plant cells. They are small squares and

they reminded him of the small rooms

in a monastery called cells

ANTON VAN LEEUWENHOEK

Credited with improving the microscope. (Zacharias

Janssen is credited with discovering/creating

microscope). Leeuwenhoek’s microscope could

magnify 200x the human eye! Today’s microscopes

can magnify up to 1500!

MATTHIAS SCHLEIDEN was a German botanist

(scientist who studies

plants.)

He found that the plant

parts he examined were

made of cells. He made

the generalization that

all plants were made of

cells.

THEODOR SCHWANN Studied animals. His microscopic investigations of

animal parts led him to generalize that all animals are

made of cells

After looking at Schleiden’s work ,he further proposed

that all organisms are made of cells.

RUDOLF VIRCHOW- OMNIS CELLULA C CELLULA”: ALL

CELLS FROM CELLS (1855) German doctor that said that new plant cells arise

only from existing plant cells, and new animal cells

arise only from existing animal cells.

Building off the work of Redi (1668) who disproved the

idea of spontaneous generation in his experiments

about rotting meat.

LOUIS PASTEUR-GERM THEORY 1856-Used the microscope to discover that tiny, one-

celled (eukaryotic) yeast created alcoholic

fermentation and that other one-celled, rod-shaped

organisms (prokaryotic bacteria) caused beverages

to spoil.

Pasteur (1864) designed a flask experiment that

disproved the idea of spontaneous generation once

and for all!

images from “amoeba Mike” and Britannica

Ask me why I don’t

have anthrax!

Early studies led to the development of the cell theory.

The Cell theory has three principles.

1) All organisms are made of cells.

Early studies led to the development of the cell theory.

The Cell theory has three principles.

1) All organisms are made of cells.

2) All existing cells are produced by other living cells.

Early studies led to the development of the cell theory.

The Cell theory has three principles.

1) All organisms are made of cells.

2) All existing cells are produced by other living cells.

3) The cell is the most basic unit of life.

There are two cell types: eukaryotic cells and

prokaryotic cells: Comparing cell types

There are two cell types: eukaryotic cells and

prokaryotic cells.

Eukaryotic cells have a

nucleus (true nucleus)which contains

DNA that forms many chromosomes.

nucleus

cell membrane

There are two cell types: eukaryotic cells and

prokaryotic cells.

Eukaryotic cells have a

nucleus.

Eukaryotic cells have

membrane-bound

organelles.

nucleus

cell membrane

organelles

There are two cell types:

eukaryotic cells and

prokaryotic cells.

Prokaryotic cells do not

have a nucleus.

Prokaryotic cells do not

have membrane-bound

organelles, but they do have

some organelles like ribosomes.

nucleus

cell membrane

organelles

cytoplasm

There are two cell types: eukaryotic cells and

prokaryotic cells.

Prokaryotic cells do not

have a nucleus, but they have one chromosome

and “extra” circular pieces of DNA called

“plasmids”. Draw a circular plasmid in your bottom

cell diagram on your notes and label it “plasmid

DNA”.

EUKARYOTIC CELLS VS PROKARYOTIC BACTERIA

CELLS

Nucleus Organelles

DNA/Chromatin Cytoplasm Cell membrane

Plasmid DNA

Eukaryotic

Prokaryotic

DNA/Chromatin

Cytoplasm

Cell membrane