Discovery and Diversity of Cells

What is a Cell?

• A membrane-covered structures that contain all the materials necessary for life.

• Smallest building block of life

Robert Hook• First person to describe Cells

• 1665 he built a microscope and looked at cork

• saw tiny boxes and called them cells

• Cell is Latin for “tiny box”

Finding Cells in Other Organisms

Anton van Leeuwenhoek• 1st to see bacteria

• discovered yeast is a single-celled organism

Matthias Schleidenstudied plants and concluded that all

plants are made of cells.

Theodore Schwann studied animals and

concluded that all animals are

made of cells.

Rudolf VirchowA doctor who discovered

that cells formed only from other cells.

Cell Theory

• All organisms are made of one or more cells.

• The cell is the basic unit of all living things.

• All cells come from existing cells.

Types of Cells• Prokaryote – cells without a nucleus.

• All prokaryotes are single-celled with no membrane bound organelles.

• Circular DNA floats around cell.

• Eukaryote (you-karyote)– cells with a nucleus

• The Nucleus is where the DNA is stored

Two types of Prokaryotes• Eubacteria

• Most common bacteria.

• They live almost everywhere on Earth.

• Smaller than eukaryotic cells, no nucleus, circular DNA.

• Archaebacteria

• Not as common as Eubacteria.

• Live in harsh conditions like hot springs, salt water, & swamps.

• Unique because cell walls made up of material different than other cell walls.

Eukaryotic Cells• The largest cells. • Can be single-celled or multi-cellular.• All have a nucleus that contains the

DNA.• Most contain membrane-bound

organelles.• Most organisms that can be seen

without a microscope are made of eukaryotic cells.

• (plants, animals, fungi, . . .)