CELLS
EQ: How did the discovery of cells change the way people look at living organisms?

Cells are membrane covered structures that contain all the materials necessary for life.

Robert Hooke (1665) built an early microscope.

He looked at thin slices of cork and saw what looked like tiny boxes or monk's CELLS.

Anton van Leeuwenhoek (1673) looked at pond scum and saw tiny "animalcules"

He also discovered that yeasts used to make bread were unicellular organisms.

Years of observation and discovery led a group of scientists to develop
THE CELL THEORY.

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

All cells have certain things in common.

Cell membrane- acts as a barrier to keep the insides in.

DNA- instructions for living and making new cells.

Organelle- tiny "organs" that allow the cell to live and grow

Cytoplasm- fluid in a cell surrounding the organelle

Almost all cells are too small to see with the naked eye.

A cell's surface area to volume ratio limits growth.

A cell interacts through its surface- gets food, gets rid of waste. When a cell gets too big for their surface area they have to divide.

multicellular benefits

• You can grow by adding more cells.
• You can have specialized cells
• You can see with eyes, hear with ears, run with legs, fly with wings, etc...

prokaryotic cells

• primitive
• no nucleus
• no membrane covered organelle
• circular DNA
• Bacteria

Eukaryotic cells

• more complex
• have a nucleus
• have membrane covered organelle
• Linear DNA
• All other organisms