Bacteria For every “human” cell, there are 20 bacteria present on our body (but they are smaller)…..this accounts for ~10% of the mass that you carry around.

prokaryote – unicellular organisms that lack a nucleus cell wall cell membrane DNA (no nucleus) ribosomes cytoplasm flagella pili

The Three Domains of Life

Kingdom Eubacteria larger kingdom more diverse can be found almost everywhere E. coli

Kingdom Archaebacteria can be found in harsh environments methanogens halophiles thermophiles may be ancestors of eukaryotes

Symbiotic Bacteria

Bacterial Shapes Bacillus – rod-shaped prokaryotes Coccus – spherical-shaped prokaryotes Spirilla – spiral and corkscrew-shaped prokaryotes

Lactobacillus

Staphylococcus epidermidis Streptococcus pneumoniae

Bacterial Locomotion Don’t move at all Propelled by flagella Spiral forward Glide via slime-like secretion

How do bacteria obtain energy? heterotrophs – organisms that obtain energy by consuming organic molecules made by other organisms autotrophs – organisms that make their own food from inorganic molecules

Release of Energy obligate aerobes – organisms that require a constant supply of oxygen in order to live obligate anaerobes – organisms that must live in the absence of oxygen facultative anaerobes – organisms that can survive with or without oxygen

Growth and Reproduction of Bacteria Binary Fission Conjugation

Extra Protection? Spore Formation… endospore forms when a bacterium produces a thick internal wall that encloses its DNA and a portion of its cytoplasm allows some bacteria to survive harsh conditions (heat, dryness, lack of nutrients)

Bacterial Growth Curve

Pathogenic Bacteria