ap biology the cell theory ap biology some random cell facts the average human being is composed of...
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AP Biology
The Cell Theory
AP Biology
Some Random Cell Facts The average human being is composed
of around 100 Trillion individual cells!!! It would take as many as 50 cells to
cover the area of a dot on the letter “i”
WOW!!!
AP Biology
Discovery of Cells 1665- English Scientist, Robert Hooke,
discovered cells while looking at a thin slice of cork.
He described the cells as tiny boxes or a honeycomb
He thought that cells only existed in plants and fungi
AP Biology
Anton van Leuwenhoek 1673- Used a handmade microscope to observe
pond scum & discovered single-celled organisms He called them “animalcules”
He also observed blood cells from fish, birds, frogs, dogs, and humans
Therefore, it was known that cells are found in animals as well as plants
AP Biology
150-200 Year Gap??? Between the Hooke/Leuwenhoek
discoveries and the mid 19th century, very little cell advancements were made.
This is probably due to the widely accepted, traditional belief in Spontaneous Generation.
Examples:
-Mice from dirty clothes/corn husks
-Maggots from rotting meat
AP Biology
19th Century Advancement Much doubt existed around Spontaneous
Generation Conclusively disproved by Louis Pasteur
Pasteur: Ummm, I don’t think so!!!
+
=?
AP Biology
Development of Cell Theory 1838- German Botanist, Matthias Schleiden,
concluded that all plant parts are made of cells
1839- German physiologist, Theodor Schwann, who was a close friend of Schleiden, stated that all animal tissues are composed of cells.
AP Biology
Development of Cell Theory 1858- Rudolf Virchow, German physician,
after extensive study of cellular pathology, concluded that cells must arise from preexisting cells.
AP Biology
The Cell Theory Complete The 3 Basic Components of the Cell
Theory were now complete: 1. All organisms are composed of one or
more cells. (Schleiden & Schwann)(1838-39) 2. The cell is the basic unit of life in all living
things. (Schleiden & Schwann)(1838-39) 3. All cells are produced by the division of
preexisting cells. (Virchow)(1858)
AP Biology
Modern Cell Theory Modern Cell Theory contains 4 statements, in
addition to the original Cell Theory: The cell contains hereditary information(DNA)
which is passed on from cell to cell during cell division.
All cells are basically the same in chemical composition and metabolic activities.
All basic chemical & physiological functions are carried out inside the cells.(movement, digestion,etc)
Cell activity depends on the activities of sub-cellular structures within the cell(organelles, nucleus, plasma membrane)
AP Biology
How Has The Cell Theory Been Used?
The basic discovered truths about cells, listed in the Cell Theory, are the basis for things such as: Disease/Health/Medical Research and Cures(AIDS,
Cancer, Vaccines, Cloning, Stem Cell Research, etc.)
It’s all about:Surface Area-to-Volume Ratio
Cell radius (r) 1 unit 10 unitsSurface area (4╥r2) 12.57 units2 1257 units2
Volume (4/3╥r3) 4.189 units3 4189 units3
Large Cells
vs.
Small Cells
Why Are Cells So Small?Size Matters!
As a cell get larger, its volume increases at a faster rate than its surface area!SA/V= 2.98 0.30
______ ______
AP Biology
Archaebacteria&
Bacteria
Classification Old 5 Kingdom system
Monera, Protists, Plants, Fungi, Animals
New 3 Domain system reflects a greater
understanding of evolution & molecular evidence Prokaryote: Bacteria Prokaryote: Archaebacteria Eukaryotes
Protists
Plants
Fungi
Animals
Prokaryote
Eukaryote
AP Biology
KingdomProtist
KingdomFungi
KingdomPlant
KingdomAnimal
KingdomArchaebacteria
KingdomBacteria
AP Biology 2007-2008
Prokaryotes
Domain Bacteria
Domain Archaebacteria
DomainBacteria
DomainArchaea
DomainEukarya
Common ancestor
AP Biology
Bacteria live EVERYWHERE! Bacteria live in all ecosystems
on plants & animals in plants & animals in the soil in depths of the oceans in extreme cold in extreme hot in extreme salt on the living on the dead
Microbes alwaysfind a way to
make a living!
AP Biology
Bacterial diversityrods and spheres and spirals… Oh My!
AP Biology
Prokaryote Structure Unicellular
bacilli, cocci, spirilli
Size 1/10 size of eukaryote cell
1 micron (1um)
Internal structure no internal compartments
no membrane-bound organelles only ribosomes
circular chromosome, naked DNA not wrapped around proteins
prokaryotecell
eukaryote cell
AP Biology 2007-2008
Eukaryotes
Domain Eukarya
DomainBacteria
DomainArchaea
DomainEukarya
Common ancestor
AP Biology
Eukaryote Structure Unicellular or Multicellular
Plant, animal, fungi, protist
Size 10X larger than a prokaryote cell
10-100 micron (1um)
Internal structure Far more complex (compartmentalized)
nucleus containing DNA other membrane-bound organelles ribosomes (no membrane)
Linear chromosome wrapped around proteins
prokaryotecell
eukaryote cell
AP Biology
Prokaryote vs. Eukaryote Chromosome
double helix
Prokaryote
Eukaryote
AP Biology
Variations in Cell Interior
internal membranesfor photosynthesislike a chloroplast(thylakoids)
internal membranesfor photosynthesislike a chloroplast(thylakoids)
internal membranes
for respiration
like a mitochondrion
(cristae)
internal membranes
for respiration
like a mitochondrion
(cristae)
aerobic bacterium
mitochondria
cyanobacterium(photosythetic) bacterium
chloroplast
AP Biology
Prokaryote Cell Wall Structure
peptide sidechains
cell wallpeptidoglycan
plasma membrane
protein
Gram-positive bacteria
Gram-negative bacteria
peptidoglycan
plasmamembrane
outermembrane
outer membrane of lipopolysaccharides
cell wall
peptidoglycan = polysaccharides + amino acid chainslipopolysaccharides = lipids + polysaccharides
That’simportant foryour doctorto know!
AP Biology
Prokaryotic metabolism How do bacteria acquire their energy &
nutrients? photoautotrophs
photosynthetic bacteria chemoautotrophs
oxidize inorganic compounds nitrogen, sulfur, hydrogen…
heterotrophs live on plant & animal matter decomposers & pathogens
AP Biology
Genetic variation in bacteria Mutations
bacteria can reproduce every 20 minutes binary fission
error rate in copying DNA 1 in every 200 bacteria has a mutation you have billions of E. coli in your gut!
lots of mutation potential!
Genetic recombination bacteria swap genes
plasmids small supplemental
circles of DNA
conjugation direct transfer of DNA
conjugation
AP Biology
Bacteria as pathogens Disease-causing microbes
plant diseases wilts, fruit rot, blights
animal diseases tooth decay, ulcers anthrax, botulism plague, leprosy, “flesh-eating” disease STDs: gonorrhea, chlamydia typhoid, cholera TB, pneumonia lyme disease
AP Biology
Bacteria as beneficial (& necessary) Life on Earth is dependent on bacteria
decomposers recycling of nutrients from dead to living
nitrogen fixation only organisms that can fix N from atmosphere
needed for synthesis of proteins & nucleic acids plant root nodules
help in digestion (E. coli) digest cellulose for herbivores
cellulase enzyme
produce vitamins K & B12 for humans
produce foods & medicines from yogurt to insulin
AP Biology
How big are cells?
Microscopic (mostly)
Measured in microns µm
(micrometers).
A µm is one millionth of a meter =
10-9 m = one thousandth of 1 mm.
AP Biology
How big are cells?
Smallest free-living cell = Mycoplasma genitalium
Size = 0.2 to 0.3 µm
AP Biology
How big are cells? Bacteria e.g. Eschericia coli (aka
E.coli) Size=1 µm by 3 µm
AP Biology
How big are cells? Human red blood cell = 8 µm in
diameter
AP Biology
How big are cells?
Largest cell on the human body =
ovum Size= 1000 µm in
diameter
(1 mm)
AP Biology
How big are cells? Smallest cell in the human body =
sperm cell.
AP Biology
How big are cells?
Largest cell with a metabolism =
Chaos chaos
Size=1-5 mm in length.
common name =
Giant Amoeba
Chaos diffluens, is an amoeba closely related to the giant amoebae
AP Biology
How big are cells? Largest cell = yolk of an ostrich egg
AP Biology
Ostrich, egg, humans
AP Biology
Ostrich emerged from egg
AP Biology
How can we study cells?
Problem:
They are microscopic!
Solution:
Use a microscope!
AP Biology
Types of Microscopes
1. Compound light microscope
Light passes through lenses to magnify image up to 1000X
Can observe living cells
AP Biology
Types of Microscopes
2. Electron microscope
Uses a beam of electrons to magnify image
> 1000X Kills cells being
observed