Download 2.3 Cell Theory and Microscopy File

Chapter 2.3
Discovering Cells
POINT > Identify how cells were discovered
POINT > Describe how different microscopes
work
POINT > Describe the development of Cell
Theory
POINT > Identify how cells were discovered
The invention of the lens
Robert Hooke (1665): observed a
thin slice of cork (dead plant cells)
with a microscope
He described what he observed as
“little boxes” (cells)
POINT > Identify how cells were discovered
Anton van Leeuwenhoek (1675): was the first
person to observe living cells
He was looking at pond water and saw “miniature
animals” swimming around
CHECK:
Who was the first person to see cells?
What was Robert Hooke looking at with his
microscope?
What was van Leeuwenhoek looking at
when he first saw living cells?
POINT > Describe how different microscopes work
Magnification refers to the
microscope’s power to increase an
object’s apparent size
Resolution refers to the
microscope’s power to show detail
clearly
POINT > Describe different microscopes
The compound
microscope
uses two lenses
to magnify
objects
CHECK:
What is magnification?
What is resolution?
How many lenses in a compound microscope?
POINT > Describe different microscopes
Elodea (aquatic plant)
with a light microscope
40X
400X
Transmission Electron Microscope (TEM)
Transmission Electron Microscope (TEM)
gives better resolution
Herpes Virus
Plant Root Cell
Scanning Electron Microscope
(SEM)
Scanning Electron Microscope (SEM) shows
even better topography
Mosquito Head
200X
2000X
Scanning Electron Microscope (SEM)
Fly Eye
Scanning Electron Microscope (SEM)
Surface of
Tongue
Neuron
Inside of
Stomach
Scanning Electron Microscope
(SEM)
Pollen
Yeast
Red Blood
Cell,
Platelet,
and White
Blood Cell
TEM vs. SEM
Viruses leaving
a cell
POINT > Describe the development of Cell Theory
Who developed the Cell Theory?
Matthias Schleiden (1838): concluded
that all plants are composed of cells
Theodor Schwann (1839): concluded
that all animals are composed of cells
Rudolph Virchow (1855): determined
that cells come only from other cells
POINT > Describe the development of Cell Theory
What is the Cell Theory?
1. All living things are composed of one or
more cells
2. Cells are the basic units of life function
3. Cells come only from existing cells
Homework:
Read pages 50-57
Finish Study Guide
GRAS pages 31-33