Chapter 4, Section 1As if you didn’t already know!

1665 made a compound microscope (a microscope with several lenses)

he placed a small piece of cork (tree bark) under his microscope

What did he see?

the cork looked like hundreds of little boxes next to one another

he named these little boxes cell, which means “little room” in Latin.

Robert Hooke

What did Robert Hookesay to his stockbroker?

Cell! Cell!

Anton van Leeuwenhoek

1673, used his handmade microscope to look at pond water. He saw small organisms in the water. Now we know that these were unicellular organisms like bacteria or protozoa.

The Cell TheoryAuthors: Matthias Schleiden, Theodor Schwann, & Rudolf Virchow

1. All organisms are composed of one or more cells.

2. The cell is the basic unit of life in all living things.

3. All cells come from existing cells.

The largest cell in the world is the yolk of an ostrich egg.It’s the size of a baseball!

What do all cells have in common?

Cell membrane(holds the cell together)

Hereditary material(DNA/genes, found in the nucleus in a eukaryotic cell)

Cytoplasm(fluid that fills cell)

Organelles(structures inside cell)

2 Types of CellsProkaryotic

(bacteria)

pro-: before

(“before nucleus” in Greek)no nucleusno membrane-bound organellescircular DNAcell wall is presentribosomes are present

draw figure 6, page 118.

Question: Define bacteria.

The rear entrance to a cafeteria!

2 Types of CellsEukaryotic (protists,

fungi, plants, & animals)

eu-:true (“true nucleus” in Greek)Nucleus is presentOrganelles presentDNA is linear Cell membrane presentCell walls present only in plants, fungi, and some protists

A Comparison Between Prokaryotes & Eukaryotes Eukaryotic cell

• Has nucleus• Membrane-covered

organelles• Linear DNA• All other cells

Prokaryotic cell

• No nucleus• No membrane-covered

organelles• Circular DNA• Bacteria

Why is it better to be a multicellular

organism rather than a

unicellular organism?

1. Multicellular organisms can grow.

2. Multicellular organisms are able to do lots of other things because they are made of different kinds of cells.

Running = nerve cells, blood cells, muscle cells, bone cells, eye cells