Download Bacteria - Cobb Learning

Bacteria
Two Kingdoms
Archaebacteria and Eubacteria
(Prokaryotes, unicellular)
Prokaryotic Cell Structure
bac vid
Bacteria
-Prokaryotes
-unicellular
-can be aerobic or anaerobic
-Two Kingdoms:
Archaebacteria and Bacteria
Identifying Bacteria
-Gram staining- a dye that causes the cell wall of
a bacterium to turn a certain color
-gram positive – turns purple
-gram negative- turns pink
-this also helps you determine what antibiotic to
use
Gram Positive (cell wall)
• Gram positive bacteria contain a layer of sugar
polymers with polypeptides woven through
them called Peptidoglycans. They protect and
anchor other surface molecules.
• Gram stain turns them purple (crystal violet).
• May release exotoxins that make you sick
(strep throat).
Gram Negative (cell wall)
• Gram negative bacteria contain a layer of
lipopolysaccharides (carbs. protruding from a lipid
based membrane, LPS) on top of a thin layer of
peptidoglycans.
• Gram stain turns them pink (safranin).
• Once they die endotoxins are released that make you
sick (salmonella)
Gram Stain Benefits
anti vid
• Antibiotics, like penicillin break down
peptidoglycans so they are affective against
gram positive bacteria.
• Gram negative bacteria are extremely harmful
because their LPS layer is toxic. They cause
fever and even shock. Strong antibiotics and
alternative medicines are needed to kill them.
Attaching to host
• Capsule- sticky outside layer of polysaccharide
or protein used to help the bacteria stick to a
host or other colony members.
• Fimbriae- hair like protrusions used to attach
itself to a host.
Movement (Motility)
• Some bacteria move by using a flagellum.
• Taxis- bacteria will move toward or away from a
stimuli, like nutrient.
Bacteria Shape and Growth
-shape provided by the cell wall
-3 shapes
-rod –
bacilli-sphere – cocci-spiral – spirilla-Growth arrangements
-paired colonies- diplo-chains- strepto-clumps- staphylo-
Bacteria Reproduction
bac vid
-Binary Fission (asexual)- the DNA replicates and
the cell divides in half.
Bacteria Reproduction
-Conjugation - protein bridge is formed between 2
bacteria, a plasmid is donated.
Transformation
• A plasmid from a dead bacteria cell is taken up
by another. Can change the geno- or
phenotype.
Transduction
• A bacteriaphage may accidentally
• transfer bacteria DNA from one
• bacteria to another.
Endospores
-endospores- a tough covering containing bacteria DNA.
-produced in unfavorable environments
-bacteria will lie dormant until conditions are right (years)
-extreme heat and acidic cleaners must be used to
sterilize surfaces containing endospores
-can cause- botulism in unsterilized canned foods, or
tetanus in wounds
Archaebacteria (Kingdom)
- Bacteria that live in extreme environments
called extremophiles
Heat Loving Bacteria,
Thermophiles
-lives in hot springs and thermal vents in the ocean
(100ºC)
Methane Producing Bacteria,
Methanogens
- Live in marshes and cow stomachs
- Used in sewage treatment plants
- Breakdown CO2 and H2
Salt Loving Bacteria, Halophiles
- Live in the dead sea and salt lakes, pump in
potassium to achieve isotonic status
Bacteria (Kingdom) p. 568
-commonly found everywhere
- We will look at them based on how they
produce their energy
Heterotrophic
-most common
-often parasites
Photosynthetic Autotrophs
-do photosynthesis to produce energy
-contain chlorophyll
-found in water (rivers, lakes, swamps, etc)
Chemosynthetic autotrophs
-use inorganic compounds to make energy (nitrogen,
sulfur)
-nitrogen fixing bacteria
Bacteria Pros
tasty vid
-fix nitrogen
-help digest food in our intestines
-decomposers
-used to make food (cheese, yogurt)
Bacteria
Cons
-Cause Diseases
-Over use of antibiotics has created more resistant
bacteria.**