1. Unit 2: Cells Chapter 3: Cells, The Basic Units of Life
Lesson 3.1: The Diversity of Cells

2. The Diversity of Cells
Most cells are so small they can not be seen by the naked eye.
How did scientists find cell’s?
CELL: the smallest unit that can perform all the processes necessary for life.

3. Cells and the Cell Theory
Robert Hooke was the first person to describe cells (1665)
He “discovered” cells by accident
He was looking at a thing piece of cork under a microscope
The cork looked like it was made of “little rooms” he called cells

4. THE CELL THEORY 1. All organisms are made of one or more cells
2. The cell is the basic unit of all living things.
3. All cells come from existing cells.

5. Cell Size – most cells are too small to be seen without a microscope (name one exception)
Why Are Cells So Small???
Cells take in and get rid of wastes through their outer surface.
As a cell gets larger, it needs more food and produces more waste.
So, more materials pass through the outer surface.

6. Surface area-to-volume ratio:
…is the ratio of the cell’s outer surface are to the cell’s volume.
= surface area
volume

7. Parts of a Cell: All cells have the following parts in common
CELL MEMBRANE: a protective layer that covers the cell’s surface and acts as a barrier. It separates the cells contents from its environment, and controls what goes into and out of the cell
CYTOPLASM: jell fluid in the cell
All organelles “float” in the cytoplasm

8. ORGANELLES: structures that perform specific functions within the cell
ORGANELLES: structures that perform specific functions within the cell. (see pg 74)
1. Nucleus
2. Ribosome
3. Endoplasmic Reticulum
4. Mitochondria
5. Chloroplast
6. Golgi Complex
7. Vacuole
8 Lysosome

9. Prokaryotic Cells: BACTERIA AND ARCHEA
Prokaryotes are single-celled organisms that do not have a nucleus or membrane covered organelles

10. BACTERIA The most common PROKAYOTES The smallest cells known
Do not have a nucleus
Have DNA – it is a long, circular strand
Have no membrane covered organelles
Have a cell membrane just inside the cell wall
See pg 64

11. ARCHEA – similar to bacteria
But can live in places no other organisms can live – in extreme conditions
Some times called extremophiles
Heat-loving
Salt-loving
Methane-making
See pg. 65

12. EUKARYOTIC CELLS – all other cells (ex. You & me & a tree)
Largest cells – but most still microscopic
About 10x larger than bacteria cells
Have a nucleus
DNA in nucleus
Membrane covered organelles
Some unicellular, most are multicellular

13. HW DUE TUES 11/22 Read Chapter 3 Lesson 2 “Eukaryotic Cell”
Make a chart in your notebook listing the organelles and their function, and if it is found in plant cells, animal cells, or both.
Include the 8 organelles in the chart on pg 74 and Cell Wall, Cytoplasm, Cell Membrane