Life Is CellularLife Is Cellular

The Cell TheoryThe Cell TheoryEarly 1600’s – Two useful Early 1600’s – Two useful

instruments were instruments were constructedconstructed

–TelescopeTelescope

–MicroscopeMicroscope

Anton van LeeuwenhoekAnton van Leeuwenhoek

One of the One of the first people first people to use a to use a microscope microscope to study to study nature.nature.

Anton van LeeuwenhoekAnton van Leeuwenhoek

Using only a single powerful Using only a single powerful lens, he crafted instruments lens, he crafted instruments that could produce magnified that could produce magnified images of very small objects.images of very small objects.

Anton van LeeuwenhoekAnton van Leeuwenhoek

His simple microscope His simple microscope enabled him to see things enabled him to see things that no one had ever seen that no one had ever seen before.before.

–First person to see tiny living First person to see tiny living organisms in a drop of water. organisms in a drop of water. (1674)(1674)

Robert HookeRobert Hooke

Robert HookeRobert Hooke1665 – English Physicist1665 – English Physicist

Used one of the first Used one of the first light microscopes to look light microscopes to look at thin slices of plant at thin slices of plant tissues.tissues.

Robert HookeRobert HookeOne of these, a slice of cork.One of these, a slice of cork.

– Under the microscope the cork Under the microscope the cork seemed to be made of thousands seemed to be made of thousands of tiny chambers.of tiny chambers.

– Hooke called these chambers Hooke called these chambers “cells”, because they reminded “cells”, because they reminded him of a monastery's tiny rooms him of a monastery's tiny rooms aka cells.aka cells.

Cork CellsCork Cells

Search For Cells In Search For Cells In Other Living ThingsOther Living Things

1838 – Matthias Schleiden1838 – Matthias Schleiden– All plants are made of cellsAll plants are made of cells

1839 – Theodore Schwann1839 – Theodore Schwann– All animals are made of cellsAll animals are made of cells

1855 – Rudolf Virchow1855 – Rudolf Virchow– Studied cell reproduction.Studied cell reproduction.– ““Where a cell exists, there must Where a cell exists, there must

have been a preexisting cell…”have been a preexisting cell…”

New DiscoveriesNew DiscoveriesThe discoveries of these and The discoveries of these and

other biologists are other biologists are summarized in one of the summarized in one of the fundamental concepts of fundamental concepts of biology.biology.

CELL THEORYCELL THEORY

Cell TheoryCell TheoryAll living things are composed All living things are composed

of cells.of cells.Cell are the basic units of Cell are the basic units of

structure and function in structure and function in living things.living things.

New cells are produced from New cells are produced from existing cells.existing cells.

Prokaryotes and Prokaryotes and EukaryotesEukaryotes

Biologists divide cells Biologists divide cells into two categories:into two categories:

–Prokaryotes and EukaryotesProkaryotes and Eukaryotes

Compare and ContrastCompare and Contrast ProkaryotesProkaryotes

– Smaller and Smaller and SimplerSimpler

– Have Cell Have Cell Membrane and Membrane and CytoplasmCytoplasm

– No NucleiNo Nuclei– Examples Examples

(Bacteria)(Bacteria)

EukaryotesEukaryotes– Larger and More Larger and More

ComplexComplex– Have Cell Membrane, Have Cell Membrane,

Cytoplasm, Nucleus, Cytoplasm, Nucleus, Dozens of Dozens of Specialized Specialized Structures Structures (Organelles)(Organelles)

– Examples: All Plants, Examples: All Plants, Animals, and Fungi, Animals, and Fungi, and Many and Many MicroorganismsMicroorganisms Some Live Solitary Some Live Solitary

LivesLives