Post on 19-Jan-2016
transcript
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
• Have NO Peptidoglycan– 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
Cyanobacteria• 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
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