Bacteria

Classification of Bacteria Archaebacteria

The extremists Oxygen – free environments

Produce methane Concentrated salt water

environments Great Salt Lake, UT The Dead Sea, Middle East

Hot, acidic waters of sulfur springs

The Great Salt Lake, UT

The Dead Sea, Israel

Eubacteria The heterotrophs

Found everywhere Need organic molecules as an energy source

Parasites Absorb nutrients from living organisms

Saprobes Organisms that feed on dead organisms or

organic waste Help recycle the nutrients contained in

decomposing organisms

Saprobe

The photosynthetic autotrophs Obtain energy from light

Cyanobacteria (cyano, blue-green) Trap the sun’s energy by

photosynthesis using their blue-green pigment

Some are red or yellow Found in ponds, streams and

moist land Composed of chains of cells

The Chemosynthetic autotrophs Obtain energy from

chemosynthetic breakdown of inorganic substances

sulfur or nitrogen compounds

Important in converting nitrogen in the atmosphere to forms readily used by plants

Underwater sea vent

Structure of BacteriaMicroscopic, simple, livingProkaryotic, no true nucleusNon-membrane bound organellesMore complex than viruses but less

than living, cellular organisms Ribosomes smaller Inherited information held in single

circular chromosome

Classification of Bacteria Shape

Spheres coccus

Rods bacillus

Spiral spirillum

Cell Arrangement Diplo – cells are paired

Staphylo – cells are in grape-like clusters

Strepto – cells are in long chains

Protection from osmotic pressure Cell walls

Made of long chains of sugar linked by short chain amino acids

Prevent osmotic rupture Most bacteria live in

hypotonic environment Water always enter in Cell wall prevents bursting of

cell

If ruptured, cell dies

Penicillin – Bacterial Killer? Interferes with the enzyme

that links the sugar chains in the cell wall

Bacteria growing in penicillin develop holes in their cell walls

Water enters, bacteria dies Not effective in viruses and

animals Neither has cell walls

Nontoxic to plants Plant cell wall is different

structure from bacterial cell wall

Miracle Cure – The Story of Penicillin

Discovered by Alexander Fleming in 1928

Produced from an airborne mold, Penicillium notatum World’s first antibiotic Purified in 1940

Kills bacteria and inhibit their growth

Penicillium notatum

Ecology and AdaptationDiversity of metabolism

Obligate aerobes Bacteria that require oxygen for cellular

respiration

Mycobacterium tuberculosis Person with tb

Types of Bacteria Obligate anaerobes

Cannot use oxygen Are killed by it

Syphilis - causing bacteria

Types of BacteriaComplex

biochemical pathways Green sulfur bacteria

Use hydrogen sulfide instead of water for photosynthesis

Produce sulfur instead of oxygen

Grow in anaerobic environments like lake sediments

Green sulfur bacteria

Adaptations for survivalEndospores

Have hard outer covering Resist drying out, boiling,

freezing, many chemicals Bacteria is in slow

metabolism, does not reproduce

When in favorable conditions, germinates and gives rise to bacterial cell

Clostridium botulinum Obligate anaerobes Form endospores Produces an extremely powerful toxin

(poison) Don’t die when exposed to oxygen Can find their way into canned food

If not properly sterilized endospores germinate

bacteria grow produce their deadly toxin

Causes botulism

Clostridium tetani Produces powerful

nerve toxin Causes often-fatal

disease, tetanus Endospores are found

in every surface Can enter wound

easily, germinate and release toxin

Immunization is prevention

Binary Fission Asexual reproduction Copies its single chromosome Copies attach to cell’s plasma membrane Cells grow in size, two copies of the

chromosome separate Cell divides into two as partition forms

between two new cells Each cell has one copy of chromosome Just like mitosis, but the whole organism

is copied

Binary fissionBinary fission

ConjugationSexual reproductionOne bacterium transfers all or part of its

chromosome to anotherPilus (pili)

Bridge-like structure Connects two cells Used to transfer genetic material

ConjugationConjugation

Convert N2 gas into ammonia (NH3)

Convert ammonia (NH3) to nitrite (NO2

-) and nitrate (NO3-)

Some form symbiotic relationship with peas, peanuts, and soybeans Helps them grow better when

nitrogen is lacking When they are harvested,

remaining roots add nitrogen to soil

Nitrogen fixation

Bacteria on legume roots

Recycling of nutrientsCyanobacteria

Replenish supply of oxygen in atmosphereAutotrophic bacteria

Convert carbon dioxide in the air to the organic compounds that are passed to consumers in food chains and webs

All life depend on bacteria

Food and medicines Used to produce vinegar,

yogurt, butter, cheese, pickles, sauerkraut

Used to produce antibiotics to kill other bacteria Streptomycin Erythromycin Chloromycetin Kanamycin

Bacteria cause diseaseHalf of human disease is caused by

bacteria

Tuberculosis Scarlet fever Rocky Mountain spotted fever

Bacterial pneumonia

Syphilis Tetanus

Botulism Gonorrhea Ear infections

Strep throat Chlamydia Boils

Staph infections Diphtheria Lyme disease