Biology

Unit 4

Notes #1

(section 3.1)

• 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

• 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

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.

• 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.)

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 O2 throughout blood

• ex: Skin Shape: Flat & broad; layers overlap– Function: Covers and protects the body

Review1) 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?