Cells

Organization of LifeDiscovery of Cells

Cell TheoryProkaryotic vs. Eukaryotic

Organization of Life

• Put your cards in order from least complex to most (what is made from what?)

Cell

TissueOrgan

Organ System

Organism

Organization of LifeCell

Tissue

Organ

Organ System

*Organism can be made of one cell or many organ systems.

Smallest unit that can carry out life’s activities

Group of cells working together to perform specific job

Group of tissues working together to perform specific job

Group of organs working together to perform specific job

Organism*

Discovery of Cells

• Most cells cannot be seen with naked eye

• So how were they first discovered?

• What was needed for their discovery?

Cells Discovered

• 1665 - Robert Hook discovered cells by accident

• Hook built a basic microscope to look at small things

• Looked at cork from a tree

Discovery of Cells

• 1673 - Anton van Leeuwenhoek looked at pond scum and saw small creatures

• Leeuwenhoek also saw that blood cells differed between animals, saw bacteria, and realized that yeast was alive

• 1838 – Schleiden concluded that all plant parts are made of cells

• 1839 – Schwann stated all animal tissues are made of cells

Cell Theory

• 1839 - Schwann developed beginning of CELL THEORY– All organisms are composed of one or more

cells.– The cell is the basic unit of life in all living

things.

• 1858 – Virchow added to CELL THEORY– All cells come from existing cells

Make a timeline of Cell DiscoveryMake a timeline of Cell Discovery

All Cell’s Have…

• Cell membrane – barrier between inside and outside of cell; controls passage of things in and out of cell

• Hereditary material – all cells contain DNA and pass a copy to new cells

• Organelles – all cells have chemicals and structures that let the cell live, grow and reproduce

• Cytoplasm - a fluid surrounding their structures

Cells

Animal Cells

Plant Cells

Bacteria

EukaryoticProkaryotic

Other Cells

Unicellular Organisms

Multicellular Organism

Other Cells

Classification of Cells

Two Types of Cells

Prokaryotic – no nucleus

Eukaryotic – have a nucleus

Prokaryotic

• Bacteria

• Smallest cells

• No nucleus

• Long, circular DNA

• Probably first type of cells on Earth (3.5 billion years old fossils)

Eukaryotic

• More complex• All living things (except bacteria) are made of

one or more eukaryotic cells• Have nucleus and many membrane-covered

organelles• Nucleus stores linear DNA• All have cell membrane, some have cell wall

also