3.1 Cell Theory
MAIN IDEA
Cells are the basic “building blocks” of all living things.
3.1 Cell Theory
The cell theory grew out of the work of many scientists
and improvements in the microscope.
• Many scientists and nonscientists, over hundreds of years
have contributed to our present day understanding of cell
structure and function.
3.1 Cell Theory
The invention of the microscope in the 1600’s provided
the opportunity to make detailed observations of cell
structures and activities.
3.1 Cell Theory
Robert Hooke 1665
Observed holes in cork under microsocope.
Coined the term “cells”
Empty spaces were actually where living cells were
before dying – he just saw cell walls
3.1 Cell Theory
Anton von Leeuwonhoek
(just call me Tony)
* Dutch lens maker
* First to observe and describe
single-celled microorganisms
Ex. bacteria and protists
* Called them animalcules and
cavorting beasties
3.1 Cell Theory
Robert Brown
Robby Bobby said –
“That dark structure found
inside many cells should be
named the Nucleus”
3.1 Cell Theory
Theodore Schleiden
Ted said “All plants are made of cells”
3.1 Cell Theory
Matthias Schwann
Matt knew where it was at when he
declared
“ALL animals (like swans) are made
of cells”
3.1 Cell Theory
Rudolf Virchow
Rejected the concept of
spontaneous generation, which
held that organisms could arise
from nonliving matter
spontaneously.
Rudy’s Rule:
“All cells are made by other cells”
3.1 Cell Theory
Theory –
An explanation for a wide body of evidence
gathered over time through observation and
experimentation.
A theory ties lots of findings together and
tries to provide a unifying explanation.
3.1 Cell Theory
The cell theory grew out of the work of many scientists
and improvements in the microscope.
• Many scientists contributed to the cell theory.
• More was learned about cells
as microscopes improved.
• The cell theory is a unifying
concept of biology.
3.1 Cell Theory
3 Principles of the Cell Theory
1. All organisms are made of cells.
3.1 Cell Theory
3 Principles of the Cell Theory
1. All organisms are made of cells.
2. All cells are made by other living cells
3.1 Cell Theory
3 Principles of the Cell Theory
1. All organisms are made of cells.
2. All cells are made by other living cells
3. Cells are the “building blocks” of all life
.
3.1 Cell Theory
There are thousands of different types of cells that make
up living organisms.
3.1 Cell Theory
Two categories of cells based on their internal structure.
1. Prokaryotic Cells
DO NOT have a nucleus or organelles surrounded by membranes
2. Eukaryotic Cells
DO have a nucleus and membrane surrounded organelles
3.1 Cell Theory
Two major cell types: Eukaryotic cells and Prokaryotic cells
Eukaryotic cells have a nucleus.
nucleus
cell membrane
3.1 Cell Theory
Two major cell types: Eukaryotic cells and Prokaryotic cells
•
•
Eukaryotic cells have a nucleus.
nucleus
Eukaryotic cells have
membrane-bound organelles.
organelles
cell membrane
3.1 Cell Theory
Two major cell types: Eukaryotic cells and Prokaryotic cells
nucleus
organelles
•
Prokaryotic cells do not
have a nucleus.
cell membrane
3.1 Cell Theory
Two major cell types: Eukaryotic cells and Prokaryotic cells
nucleus
organelles
•
Prokaryotic cells do not
cell membrane
have a nucleus.
•
Prokaryotic cells do not
have membrane-bound
organelles.
cytoplasm
3.1 Cell Theory
Fossil Evidence of Prokaryotic and Eukaryotic Cells
PROKARYOTES
EUKARYOTES
Photosynthetic marine bacteria Evolved 1.5 billion yrs ago
3.5 Billion Years Ago
First ones were unicellular
Later cells became
multicellular
3.1 Cell Theory
Organisms are made of either prokaryotic or eukaryotic cells
Prokaryotes are organisms made of Prokaryotic cells
Only Bacteria are Prokaryotes
•
•
•
•
Eukaryotes are organisms made of Eukaryotic cells
Organisms include:
Protists
Fungi
Plants
Animals
3.1 Cell Theory
Cells come in many different shapes and carry out
many different jobs. However they all share some
features.
All cells do share some characteristics
• Most cells are microscopic.
Bacterium
(colored SEM; magnification 8800x)
3.1 Cell Theory
All cells share some characteristics
• Most cells are microscopic
• All cells are separated from their environment by a
plasma membrane
cell membrane
Bacterium
(colored SEM; magnification 8800x)
3.1 Cell Theory
All cells share some characteristics
• Most cells are microscopic
• All cells are enclosed by a plasma membrane
• All cells are filled with gel like fluid called cytoplasm
cell membrane
cytoplasm
Bacterium
(colored SEM; magnification 8800x)
3.1 Cell Theory
All cells share some characteristics
•
•
•
•
Most cells are microscopic
All cells are enclosed by a plasma membrane
All cells are filled with cytoplasm
All cells contain DNA
cell membrane
cytoplasm
Bacterium
(colored SEM; magnification 8800x)
3.1 Cell Theory
3.1 Cell Theory
Endosymbiotic
Theory
• Developed
in the 1970’s
• Endosymbiosis- a relationship in which one organism lives
within the body of another and both benefit from
relationship.
• Early mitochondria and chloroplasts were once simple
prokaryotic cells that were taken up by larger prokaryotes
around 1.5 bya. Some of the smaller prokaryotes may have
survived inside the larger ones. Survival advantage-Both
structures helped the larger cell get energy.
Mitochondria and Chloroplasts have their own DNA &
ribosomes, can copy themselves
3.1 Cell Theory
Endosymbiosis
3.1 Cell Theory
Helpful Animations and Videos
Prokaryotic vs. Eukaryotic Cells: Comparison and Contrast
http://science.howstuffworks.com/life/28732-assignmentdiscovery-elements-of-cells-video.htm
http://www.youtube.com/watch?v=y623clAREHI
http://www.youtube.com/watch?v=yWy4o_UfZ4A
http://www.youtube.com/watch?v=WRO-DPyB9Bk
3.1 Cell Theory
Parts of a Prokaryotic Cell
3.1 Cell Theory
Prokaryotic Cells
No Nucleus
Eukaryotic Cells
Nucleus
No membrane surrounded
organelles
Membrane surrounded
organelles
Smaller
Larger
Single celled/ Unicellular
Single or Multicellular
Found in bacteria, archaea Found in protists, fungi, plant
and animals
Circular DNA
Linear
DNA
Ribosomes – not
Ribosomes (protein factories)
surrounded by a
membrane
3.1 Cell Theory