Bacteria
“bacteria by Jonathan Coulton
Objectives
• Define Bacteria, eubacteria, & archaebacteria,
and note the relationships between them.
• Methods used to classify bacteria
• Describe 3 types of archaebacteria
• Gram-positive vs. Gram-negative bacteria
• Structure of a bacteria cell
• How they move
• Bacterial genetic recombination
• It’s their planet, they were here first,
and there’s more of them than us.
• They’re microscopic prokaryotes
– No nucleus, ect…
The bacteria save us in
War of the Worlds
Evolution
• They’ve been evolving for 3.5 billion years,
that’s a lot of time to turn into different
species.
• They’ve found ways to survive almost
everywhere. Some can “hibernate” in
space
– Leads to interesting ideas
How many?
•
•
•
•
40 million bacteria in a gram of dirt
1 million in a mL of fresh water
5x1030 bacteria in the world
Your body has 10x’s more bacteria cells
than human cells in it
Classification
• A lot of bacteria look pretty much alike
• Group them on…
– Structure, physiology, how they react to dif.
Types of staining techniques
• OR group them on RNA similarity
Why did the bacteria cross the
microscope?
• To get to the
other slide.
Two kinds of bacteria
• Eubacteria
• Archaebacteria
– More ancient group
Archaebacteria
• Have weird lipids on their
membranes
• Have introns in their DNA
NO
Peptidoglycan
• Have
– A protein/carb mix
Extremophiles
• Love extremes
• No competition there
• Places to salty, acidic, hot or cold, for life
Methanogens
• Oxygen kills them
• Live at bottom of swamps, or in sewage
• Can combine O2 and CO2 into methane
– Swamp gas
• And in your gut
– Enteric bacteria
– E. Coli  a facultative anaerobe: It can live with or
without O2
– Obligate anaerobes: Have to live where there’s no O2
Halophiles & Acidophiles
• Halophiles: Love salt
– Live in the dead sea
– 2nd saltiest water on
Earth
– 8x’s saltier than
oceans
– Lowest point on earth
not covered by ice
– 418 M below sea level
Dead Sea
• King David,
Herod, Jesus,
John The
Baptist,
• Jericho is just
north (oldest
continually
occupied town
• But the sea is
shrinking
– People need
water
Volcanic acid lake in Gorley
(Kamchatka, Russia)
• A
crowbar
will
dissolve
in about
an hour
in this
lake
Acid Lake in Taal, Phillipines
•
Sulfuric vents at the
lake’s edge
Eubacteria
• Rod shaped: Bacilli
• Sphere shaped: cocci
– Linked in a chain:
streptococci
– Grape-like clusters:
staphylococci
• Spiral shpaed: Spirilla
Gram Stain
• Gram-positive: keep the
stain, show up purple
– They have peptidoglycan
– These bacteria make yogurt
• Gram-negative: don’t take
the gram stain, but do take
a pink stain instead
– Rhizobium: makes N2 gases
usable by plants
• The difference: Make dif, chemicals,
react to dif antibiotics and disinfectants
• Not plants, but do
photosynthesis
• Heterocysts: a kind
that makes Nitrogen
usable for plants
• If you put a lot of
nitrogen into a water
supply you get a
population bloom
– Eutrophication: all
these bacteria suck up
the oxygen and
everything else in the
water dies
Cyanobacteria
Genetic recombination
• Without reproducing bacteria can acquire
and express new genetic info
• Transformation: Bacteria take in DNA
around it
• Conjugation: Bacteria use pilli to make a
bridge between each other and uses
plasmids
• Transduction: viruses carry DNA between
bacteria