BACTERIA NOTES

Cellular Evolution – Prokaryotes and Eukaryotes Current evidence indicates that eukaryotes evolved from prokaryotes between 1 and 1.5 billion years ago Two theories: 1. Infolding theory 2. Endosymbiotic theory

Infolding Theory The infolding of the prokaryotic plasma membrane gave rise to eukaryotic organelles. infolding organelle

Endosymbiotic Theory Endosymbiosis refers to one species living within another(the host) Movement of smaller photosynthetic & heterotrophic prokaryotes into larger prokaryotic host cells Formed cell organelles chloroplast mitochondria

Prokaryotes - Bacteria Unique Characteristics: Microscopic prokaryotes Small ribosomes Single, circular chromosome (DNA) in nucleoid region

Size of Bacteria

Three Domains of Life Archaea – prokaryotes living in extreme habitats Bacteria- Cyanobacteria and eubacteria Eukarya – Protozoans, fungi, plants, & animals

Bacteria Kingdoms Eubacteria Archaebacteria Most common Found everywhere First living cells (?) Photoautotrophs Contain chlorophyll but not inside a chloroplast Withstand hostile environments Nicknamed “extremophiles”

Archaebacteria vs. Eubacteria

Classification OF BACTERIA - based on shape

Shapes Are Used to Classify Bacillus: Rod shaped Coccus: Spherical (round) Vibrio: Comma shaped with flagella Spirillum: Spiral shape Spirochete: wormlike spiral shape

Grouping of Bacteria - Prefixes Diplo- Groups of two Strepto- chains Staphylo- Grapelike clusters

Diplococcus

Streptococcus - Causes Strep Throat

Staphylococcus

Bacillus - E. coli

Streptobacilli

Spirillum and Spirochetes – Lyme Disease and Syphilis

Bacillis anthraxis Mycobacterium tuberculosis Actinobacillis bacterium

Classification based on cell wall Uses Gram staining Named for a Danish bacteriologist, Gram staining is a technique for the identification of bacteria in which a violet dye is applied.

Gram Positive Gram Negative Thick cell wall made of peptidoglycan (protein-sugar complex) Retains purple stain Antibiotics keep cell walls from forming correctly Cells die Gram Negative Thinner cell walls Stain washes away Antibiotics won’t work

EXAMPLES Gram Negative Gram Positive Rhizobacteria - grow in root nodules of legumes (soybeans, peanuts) Fix N2 from air into usable ammonia (NH3) (nitrogen fixation) Rickettsiae -parasitic bacteria carried by ticks Cause Lyme disease & Rocky Mountain Spotted Fever Lactobacilli (makes yogurt & buttermilk) Actinomycetes (make antibiotics) Clostridium (lockjaw bacteria) Streptococcus (strep throat) Staphylococcus (staph infections) 22

Bacteria Obtain and Use Energy Heterotrophs: don’t make own food Saprobes – feed on dead organic matter Parasites – feed on a host cell Autotrophs: can make own food Bacteria can be “photoautotrophs” or chemoautotrophs”

Cyanobacteria Gram negative, photosynthetic Called blue-green bacteria Contain phycocyanin (red-blue) pigments & chlorophyll - may be red, yellow, brown, black, or blue-green May grow in chains (Oscillatoria) First to re-enter devastated areas Some cause Eutrophication (use up O2 when die & decompose in water)

Types of cellular Respiration in bacteria Obligate Aerobes – require O2 (tuberculosis bacteria) Obligate Anaerobes – die if O2 is present (tetanus) Facultative Anaerobes – don’t need O2, but aren’t killed by it (E. coli) Anaerobes = carry out fermentation Aerobes = carry out cellular respiration

BACTERIAL Reproduction Bacteria reproduce asexually by binary fission Single chromosome replicates & then cell divides Rapid; All new cells identical (clones)

Binary Fission (asexual reproduction)

Endospores Form endospore whenever when habitat conditions become harsh (little food) Able to survive for long periods of time as endosperm Difficult to destroy (heat resistant)

Conjugation (sexual reproduction) A tube forms between 2 bacteria to exchange genetic material Held together by pili New cells NOT identical Pilus

Beneficial Uses of Bacteria Food: yogurt, cheese, soy sauce Symbiotic Relationships: E.coli in intestines, nitrogen fixation Recycling Nutrients: sewage Industrial: oil spills, mining Medicine: antibiotics, genetic research