CONTRIBUTIONS TO THE CELL THEORY

Timeline of scientists and their discoveries

1) Anton von Leeuwenhoek

1600’sDutch businessmanInvented 1st simple light microscope

Anton von Leeuwenhoek (con’t)

Observed tiny organisms in pond waterOrganisms were nicknamed “wee beasties”

2) ROBERT HOOKE

1665English physicistObserved flowers, insects, and plant tissue

ROBERT HOOKE (con’t)

Observed thin slices of cork (oak tree)Coined the term “cell” based on the rooms in a monastary

3) ROBERT BROWN

1833Observed plant cells under the microscope

ROBERT BROWN (con’t)

Observed a dark structure inside each cell and coined the term “nucleus”

4) MATTHIAS SCHLEIDEN

1838German botanist: scientist who studies plantsConcluded all plants are made up of cells

5) THEODORE SCHWANN

1839German biologistConcluded all animals are made of cells

6) RUDOLF VIRCHOW1855German PhysicianStudied cell reproductionConcluded all cells arise from preexisting cells

The cell theory

1. All living things are composed of cells2. Cells are the basic unit of structure and function in living things.3. All cells arise from preexisting cells.

Introduction to Cells

Chapter 6

Levels of OrganizationAll living organisms can be studied on many levels

From smallest to largest they are:Chemical (atoms & molecules)

Cells

Tissues

Organs

Organ Systems

Whole Organism

Basic Structure of Cells

All cells have a cell membrane and cytoplasmCell Membrane: thin, flexible barrier around cell

Composed of lipids and proteins

Cytoplasm: jelly-like material inside the cell

All cells contain organellesOrganelles: small structures that perform different functions within a cell

Prokaryotic Cells

Do NOT have a nucleusInstead a small ring of DNA is free-floating in center of cell

Organelles do NOT have a membrane

i.e.: bacteria (very simple organisms)

Eukaryotic Cells

Contain a nucleus

Organelles are membrane-bound

Much more complex

i.e.: plants, animals, fungi