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Prokaryotes
March 24, 2010
Prokaryotes
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Prokaryotes
March 24, 2010
Classification based on:
• shape
• Structure of cell wall
• Source of food/energy
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SHA PE
Cocci ­ round (singular is coccus)
Bacilli ­ rod­shaped (singular is bacillus)
Spirilli ­ spiral shaped (singular is spirillum)
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Staphylo­ ... grows in clusters (like grapes)
... grows in pairs
Strepto­ ... grows in chains
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Prokaryotes
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Gue
March 24, 2010
!
Who
Streptococcus mutans
the bacteria that causes tooth
decay by using the sugars we
eat. The by­product of the
sugar consumption is a acid that
eats away at our enamel,
causing cavities and tooth
decay
Staphylococcus aureus
the bacteria found on about 1/3 of our skin. can
cause minor infections of the skin or serious
illness such as pneumonia.
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Two Main Membrane Structures
gram negative
gram positive
Gram staining is a process developed by Hans Gram in which the
cell wall is stained purple. The purple attaches to the peptidoglycan
component of the cell wall. Gram positive cells show up purple
while gram negative cells appear pink (becuase they do have a thin
layer of peptidoglycan between the cytoplasmic membrane and the
outer membrane!
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Is this one bacteria specimen or two different species?
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Prokaryotes
March 24, 2010
Still look the same?
Escherichia coli
Bacillus anthracis
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Nutrition
Photoautotrophs ­ receive their energy
from the sunlight and their carbon
source is CO2
Example: Cyanobacteria
Photoheterotrophs ­ receive their energy
from the sunlight and their carbon source
is organic carbon compounds (ex.
carbohydrates, fatty acids and alcohols)
Example: Purple non­sulfur bacteria
Chemoautotroph ­ obtain the carbon
and energy required for life processes
from breaking apart inorganic
compounds
Example: Nitrobacter
Chemoheterotrophs ­ Both the
energy and carbon source comes
from organic matter.
Example: Escherichia coli
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Prokaryotes
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Conjugation
A method of genetic
recombination in bacteria
Involves the exchange of some or
all of a bacteria's genetic code
with another individual
Cells become linked with a pilus
­ a long tube­like structure
Binary fission then occurs and
then daughter cells are
genetically different from the
mother cell was prior to the
genetic exchange
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Plasmids
Small loops of DNA that are separate from the main
chromosome. Also genetically different from the main
chromosome and can range in size from one gene to
many genes. Plasmids can be transferred from one
cell to another during conjugation.
Used in recombinant DNA technology that can give
new traits to an organism. Ex. cloning the gene for the
production of insulin in humans.
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Endospores
When conditions are unfavorable to the bacteria, the
organism can form an endospore. The endspore
contains the DNA and a small amount of the cytoplasm.
While the bacteria is in the endospore phase, the
organism does not grow or reproduce. They are
extremely resilant to extreme weather conditions
including temperature and water availability. When
the conditions become favorable again the endospore
loses its protective coat and the bacteria begins to
grow and divide again.
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Prokaryotes
March 24, 2010
Bacteria and Us!
Bacteria help us break down compounds that cannot be broken
down by enzymes. Ex. Beans and cabbage contain sugars that are
too big to enter our cells, but we cannot break them down into
more manageable sizes. So, bacteria help us do this and the by­
product of them breaking down the sugar is methane gas...hence
the...
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The resistant bacteria are called MRSA, or Methicillin Resistant Staphylococcus aureus, or VRSA,
Vancomysin Resistant Staphylococcus aureus, depending on which antibiotic the S. aureus is resistant to.
VRSA is a stronger resistance than MRSA; there has been less cases of VRSA.
http://www.youtube.com/watch?v=CLevnx6dZ3E
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Bacteria and the Environment
Cyanobacteria ­ produce oxygen for their environment
through photosynthesis. Also form the bottom of the
food chain, providing food for larger species above
them in the food chain. Some species of cyanobacteria
fix nitrogen for their environment.
Chemoheterotrophs ­ break down organic material,
helping the nutrients that individual used re­enter their
cycle...Ex. Carbon, hydrogen, etc...
Chemoheterotrophs such as sulfate­reducing bacteria help
convert sulfur from a form that is not usable by organisms to a
usable form by breaking down hydrogen sulfide.
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