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