BIOLOGY
Biology 1
Summer
2016-2017
Outline
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Cell Theory
Cell Structure and Functions
Prokaryotic vs Eukaryotic Cells
Cell Types
Cell Modifications
3 Postulates of Cell Theory
1. All organisms are made up of one or more cells.
2. Cells are the smallest unit of life.
3. All cells come from pre-existing cells
Why?
LIFE
Living or Non-Living?
Bread Mold
Penicillium
Living or Non-Living?
Living or Non-Living?
History of Cell Theory
Aristotle
• Greek philosopher, 3rd Century BC
SPONTANEOUS GENERATION
- Non-living  Living
- abiogenesis
- heterogenesis
Spontaneous Generation
How to make mice?
21 Days
How to make maggots?
Let it rot
History of Cell Theory
• 1668 Experiment
• BIOGENESIS THEORY
History of Cell Theory
1665- CELLS
History of Cell Theory
Anton van
Leeuwenhoek
(1632-1723)
History of Cell Theory
• 1674 – Animalcules on pond scum
History of Cell Theory
• Challenged Redi’s findings
• 1748 Experiment with Broth
John Needham
1713-1781
With
bacteria
History of Cell Theory
• Needham’s conclusion:
Bacteria growth brought about by the broth
• Spontaneous generation
• Flawed: Heat not boil!
History of Cell Theory
• Challenged Needham’s findings
• 1768
Lazzaro Spallanzani
1729-1799
History of Cell Theory
• 1859 Swan Neck Flask Experiment
Louis Pasteur
1822-1895
History of Cell Theory
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Conclusion
Air  with bacteria, contaminated the broth
Life from Life
Spontaneous or Biogenesis?
History of Cell Theory
• 1800’s improvements in
quality of microscopes
• After almost 200 years
from Leeuwenhoek
• More detailed
observations on
microscopic structures
History of Cell Theory
• Observed plant cells
• 1833 Named Nucleus
• Involved in fertilization
Robert Brown
1773-1858
History of Cell Theory
1804 –1881
• Matthias Scheiden
• Studied plant
structure
• 1838 All parts of plant
composed of cells
• Cells get pregnant
History of Cell Theory
• Theodor Schwann
• Studied animal and
human bodies
• 1838: All animal parts
are composed of cells
1810 –1882
History of Cell Theory
• Summary of Schwann’s observations
1. Cell is the unit structure of all living things.
2. Cells can exist on its own or are the building
blocks of organisms
3. Cells form by free-cell formation (like crystals)
History of Cell Theory
• Rudolf Virchow
• 1855 Cells come from preexisting cells
1821 – 1902
Cell Theory
1. All known living things are made up of cells.
• (There is a boundary between life and non-life)
2. The cell is structural & functional unit of all living things.
(When living things feed themselves, metabolize, grow, reproduce, respond and move,
die – cells alone are doing the job.)
3. All cells come from pre-existing cells by division.
• (Spontaneous Generation does not occur)
4. Cells contain hereditary information which is passed from cell to cell during cell
division.
• (Again no magic or supernatural forces, no spontaneous generation neither)
5. All cells are basically the same in chemical composition.
• (No vital forces required)
6. All energy flow (metabolism & biochemistry) of life occurs within cells.
Prokaryotic vs Eukaryotic
• PROKARYOTIC
• EUKARYOTIC
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Before the nucleus
No compartmentalization
0.2-2.0 um diameter
Simpler
Free-living cell
Eubacteria,
archaebacteria
With true nucleus
With compartmentalization
10-100 um diameter
More complex
Free-living or multiple
Plant, animal, fungi,
protozoa
Prokaryotic vs Eukaryotic
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Common Features
Plasma Membrane
Cytoplasm
DNA and RNA
Obtain energy and nutrients from environment
Chemical Composition
– Water 70%
– Salts, lipids, amino acids, nucleotides 7%
– Macromolecules 23%
• Microscopic
Why are cells small?
As the cell gets larger, it requires
more resources to be imported and
produces more products (and waste)
to be exported.
Therefore, a larger volume requires
more exchange across the membrane.
http://commons.wikimedia.org/wiki/Sphere
Diffusion Pathways
are shorter (and
more efficient)
in
with a larger
surface are to
volume ratio.
http://commons.wikimedia.org/wiki/Sphere