Download Cell Biology The Cell Theory

10/24/2013
If all living things are made from cells,
then what does that include?
Cell Biology
Volvox globator
What is a cell?
Escherichia coli
A chicken egg and an ostrich
egg
Eubacteria
Archaebacteria
Protists
Fungi
Plants
Animals
Brief History of The Cell Theory
 It is the smallest unit of
life that is classified as a
living thing, and is often
called the building
block of life.
 The cell is the basic
structural and functional
unit of all known living
organisms.
 Some organisms are
unicellular (made of
only one cell) while
others are multicellular
(made up of several
cells).
The Cell Theory
Cells are the basic units of life
All living things are made up of cells.
 The cell was first discovered
by Robert Hooke in 1665.
 He examined very thin
slices of cork and saw a
multitude of tiny pores that
he remarked looked like the
walled compartments of a
honeycomb.
 Because of this, Hooke
called them cells, the name
they still bear. However, he
did not know their real
structure or function.
Diagram of a louse from
Hooke's book,
Micrographia
Brief History of The Cell Theory
 The first man to witness a live cell under a microscope
was Antonie Phillips van Leeuwenhoek, who in
1674 described the algae Spirogyra and named the
moving organisms animalcules, meaning "little
animals". Leeuwenhoek probably also saw bacteria.
Antonie van
Leeuwenhoek
New cells are made from existing cells.
This theory applies to anything living!
A drawing of a tree
section made by
Van Leeuwenhoek.
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 In 1839, Theodor
Schwann and
Matthias Jakob
Schleiden
suggested that
cells were the
basic unit of life.
 In 1858, Rudolf
Ludwig Virchow
concluded that all
cells come from
pre-existing cells,
thus completing the
classical cell
theory.
M. Schleiden
T. Schwann
Antoine Phillips van
Leeuwenhoek’s microscope
Evolution of Microscope
Brief History of The Cell Theory
Robert Hooke’s microscope
Optical microscope
Electron microscope
Digital microscope
R. Virchow
Who Discovered the Cell Theory?
1665 – Robert Hooke
What the Cell?!
size & _____
shape of a cell relate to its function.
The ____
• Looked at cork & named cells
1674 – Anton van Leeuwenhoek
• Looked at living cells & improved microscope
I am a
heart cell!
I am a
skin cell!
1838 – Matthias Schleiden
I am a
prison
cell!
• Looked at plants & determined that plants were made of cells
1839 – Theodor Schwann
• Looked at animals & determined that animals were made of cells
1855 – Rudolph Virchow
• Stated that all cells come from other living cells
How Did They See the Cell?
They used microscopes!
 Micro means ________.
SMALL
 A microscope is a tool we use to see small
objects.
Cell Specialization – Division of Labor
PRACTICE QUESTION
An advantage that multicellular organisms have over
unicellular organisms is that –
a. unicellular organisms can grow larger than
multicellular
b. unicellular organisms are more complex than
multicelluar
c. multicellular organisms can rid waste more efficiently
d. multicellular organisms can divide the work into
specialized cells
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What the Cell?!
All cells have 4 things in common:
Surrounded by a barrier = Cell
Membrane
Cytoplasm
Ribosomes
At some time, they contain DNA/RNA
Molecules that store & transmit
genetic info
Cell Membrane: Phospholipid Bilayer
Cytoplasm
 It is the part of a cell that is enclosed within the cell
membrane.
 The cytoplasm is the site where most cellular
activities occur, such as many metabolic
pathways like glycolysis, and processes such as cell
division.
Schematic showing the
cytoplasm, with major
components of a typical
animal cell
Cytoplasm: Its Components
1. The cytosol is the portion of
a cell that is not enclosed
within membrane-bound
organelles. It is a
translucent fluid in which the
other cytoplasmic elements
are suspended. It makes up
about 70 % of the cell
volume and is composed of
water, salts and organic
molecules.
2. Organelles are membranebound compartments within
the cell that have specific
functions.
What is an Organelle?
Internal structure
Enclosed in a membrane
 Thin layer of cover or lining
Specific function (job)
“Little Organ”
Organelles
What is a Nucleus?
Large structure
Enclosed in a membrane
 Thin layer of cover or lining
Contains the cell’s DNA
Controls many cell activities
Nucleus
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Nucleus
An electron micrograph of
a cell nucleus, showing the
darkly stained nucleolus.
 The nuclear envelope is a double membrane
that encloses the entire organelle and separates
its contents from the cellular cytoplasm.
 The viscous liquid within it is
called nucleoplasm, and is similar in
composition to the cytosol found outside the
nucleus.
 The nucleolus is a discrete densely stained
structure found in the nucleus.
Types of Cells
Prokaryotes vs. Eukaryotes
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Venn Diagram of Cell Types
Prokaryotes
•No nucleus
•Smaller
•Simpler
•Cell membrane
•DNA
•Carry out a
variety of
activities
•Cytoplasm
•Ribosomes
Eukaryotes
• Nucleus
• Larger
• Complex
• Membrane-bound
organelles
Types of Cells
Prokaryote
Pro = No
Eukaryote
No nucleus.
Genetic material
NOT contained in
a nucleus
Nucleus that
contains genetic
material
Generally smaller
& simpler
Generally larger
& more complex.
Have
membrane-bound
organelles.
Bacteria
Plants, Animals,
Fungi, & Protists
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