2. Biology Unit 4 Notes #1 (section 3.1)

3. All life is made of cells Cells discovered after microscope invented 1665: Robert Hooke first observed cork (dead tree bark) –Boxes he saw reminded him of tiny rooms –He named the empty boxes “cells” 1670’s - Anton van Leeuwenhoek- observed microscopic living things

4. Three Parts: –1) All organisms are made of cells –2) The cell is the most basic unit of life –3) Cells come from other cells All plants are made of cells All animals are made of cells All cells come from other cells

5. Types of Microscopes A compound microscope is a light microscope that uses more than one lens to enlarge images up to 1,500 times their original size.

6. An electron microscope can magnify an image up to a million times or more. Because objects must be mounted in plastic and sliced, a transmission electron microscope (TEM) can only be used to view nonliving objects. A scanning electron microscope (SEM) is used to view a three-dimensional image of an object Types of Microscopes (cont.)

7. Cell Diversity Shape depends upon function ex: Nerve Shape: Elongated branching –Function: Sends messages to and from brain ex: Red Blood Shape: Disc-like shape prevents clogging –Function: Carries O 2 throughout blood ex: Skin Shape: Flat & broad; layers overlap –Function: Covers and protects the body

8. Review 1)Who first identified cells? 2)What was he/she examining? 3)Name the three parts to the cell theory. 4)Explain how the shape of a blood cell allows it to perform it’s job better. 5)What it the biggest perk to an electron microscope? 6)What it the biggest drawback to an electron microscope?