BACTERIA Unicellular Organisms Prokaryotes (no true nucleus)

BACTERIAL STRUCTURE Characteristics : Rigid cell walls (can be damaged by antibiotics). No membrane bound organelles No nucleus just a central chromosome (DNA) or nucleoid that floats in the centre of the cytoplasm. Bacteria do have ribosomes No mitochondria or chloroplasts

BACTERIAL STRUCTURE Chomosome (DNA - controls cell) Plasmid (DNA – extra, can give antibiotic resistance) Cytoplasm (fluid inside cell) Cell wall (maintains cell shape) Cell membrane (controls what entres & exits the cell) Ribosomes (protein synthesis) Flagella (for movement [motility]) Pili (sticks bacteria to other cells ) Capsule (slimy outer layer - protects)

BACTERIAL SHAPES & COLONIES Shapes: cocci - round (coccus singular) bacilli - rod-shaped (bacillus) coccobacillus spirilli - spiral-shaped (spirillum) Colonies: diplo - cells arranged in pairs staphylo - cells arranged in clusters (grapes) strepto - cells arranged in a chain

Arrangements of Cocci

Shapes and Arrangements Coccus – Spherical or oval bacteria STAPHYLOCOCCUS AUREUS STREPTOCOCCUS

Shapes and Arrangements Bacilli – Rod-Shaped BACILLUS ANTRACIS COCCOBACILLUS

Shapes and Arrangements Spirals – Vibrio – curved, comma-shaped – Spirillum – thick, rigid spiral – Spirochete – thin, flexible spiral VIBRIO FISCHERI SPIROCHETE

ENERGY SOURCES 1. Light energy 2. Energy from the chemical breakdown of inorganic compounds (ex rocks) CARBON SOURCES 1. Inorganic CO 2 - Autotrophs (producers) 2. Organic carbon - Heterotrophs (consumers)

OXYGEN TOLERANCE 1. Aerobic – need O 2 (ex - decomposers, skin bacteria etc....) 2. Anaerobic – O 2 is toxic it kills these bacteria (ex – decomposers [causes compost to smell], botulism bacteria, etc.....) 3. Facultative anaerobes – can live with or without O 2 (ex - decomposers, bacteria used to make wine & beer[with O 2 the bacteria makes acid ] etc....)

Biological Role Decomposition (organic materials) Food digestion (symbiotic bacteria - mutualism) Disease (Parasites) Plant Growth (fix nitrogen - mutualism) Human Food (cheese, yogurt, …) Production of food /O 2 (part of food chain)

Methods of Reproduction Asexual Reproduction in Bacteria: Binary Fission Repeated doubling called exponential growth Single chromosome replicates (doubles) Cell grows then divides in two Each new daughter cell receives one identical piece of DNA

“Sexual” Reproduction in Bacteria (changing the DNA to increase genetic diversity) 1)Conjugation: Bacterial cells become linked with pili. One bacterium transfers all or part of the chromosome or a plasmid to another bacteria.

2) Transformation Extracellular DNA uptake Bacteria can take up a piece of DNA floating free in the environment Scientists use this to trick bacteria into making products that we need (ex insulin) 3) Transduction Some viruses (bacteriophages) can inject DNA into bacteria We can use these viruses to – Get bacteria make products we need or – Kill bacteria we don’t want (virus acts as parasite in a host bacteria)