Kingdom Eubacteria in 23 slides

Kingdom Eubacteria  Normal, everyday bacteria & photosynthetic bacteria  Unicellular  Small—0.5 to 1.5 micrometers

Structure  Prokaryotic  No organized nucleus— DNA is free-floating in the cytoplasm  No membrane-bound organelles  Many enzymes are attached to the plasma membrane  Ribosomes are the only cytoplasmic organelles—smaller than eukaryotic ribosomes

Structure DNA Cell wall cytoplasmribosomes Plasma membrane capsule (in some species)

Capsule  A gelatinous covering found on some species of bacteria  Contributes to virulence  Protect pathogenic bacteria from phagocytosis by cells of the host

Cell Wall  Strong and semi-rigid  Gives the cell its shape  Protects cell from changes in moisture and the actions of many drugs  Penicillin stops the formation of the cell wall in bacteria

Plasma membrane  In prokaryotes, consists primarily of phospholipids and proteins  Phospholipid bilayer with integral & peripheral proteins  Selectively permeable

DNA  A single long circular molecule of DNA—the bacterial chromosome  Carries all the information required for the cell’s structures & functions  In actively growing bacteria, as much as 20% of cell volume is occupied by DNA

Plasmid DNA  Small, circular DNA molecules  Usually carry from 5 to 100 genes  Generally not for the survival of the bacterium under normal environmental conditions

Ribosomes  Site of protein synthesis  A bacterial cell will have tens of thousands

Bacterial Cell Extensions  Pili—submicroscopic hair-like structures (bristles)  Allow bacteria to stick to surfaces & to each other (ex.—E. coli)  Flagella—long protein extensions of the cell (tail)  Used for movement

Shapes  All known species of bacteria are one of three basic shapes:

bacillus

coccus

spirillum

SUCCESS!!!  In terms of numbers and distribution…the most successful organism on the planet!  WHY???  Reproduce rapidly  Some live in and/or feed on materials that are poisonous to anything else  Can exist under extreme conditions  High rate of mutation makes them very adaptable and very difficult to get rid of

Ecology  Found in every habitat  Each square inch of your skin has about 100,000 bacteria!

Consumers  Consumers  depend on other organisms for food  Saprobe—gets energy from dead &/or dieing organisms (plant/animal/&c.)  decomposers  =nature’s recyclers…recycle nutrients

Producers  Photosynthetic bacteria  Produce own food using sunlight & inorganic materials  Chemosynthetic bacteria  Use a photosynthesis-like process using sulfur & iron compounds (thermal deep sea volcanic vents)

Oxygen requirements  Obligate aerobe  Must have free oxygen (O 2 )  Obligate anaerobe  Can not live in the presence of free oxygen  Facultative anaerobe  Can grow with or without free oxygen

Importance of bacteria  Disease—tetanus, gas gangrene, Salmonella, bubonic plague, strep throat, tuberculosis, botulism, Lyme disease, syphilis, &c.  Food—cheese, yogurt, sour cream, pickles, sauerkraut, &c.  Industry—clean up oil spills, produce medicines, genetic material, snow making, &c.  Environmental—recycle nutrients, break down dead tissue, base of much of food chain, symbiotic with many species of organisms…

Reproduction bacterial cell DNA replicates DNA splits Cell wall pinches two new genetically identical cells = asexual reproduction (a- = without, not) BUT…if bacteria are asexual, doesn’t that mean that they will always stay the same? How do they adapt to new environmental situations?????

Bacterial change???  Epigenetic factors—tweak the active genes  Mutation  Bacteria have a high rate of mutation (permanent change in the DNA of an organism)  Horizontal Gene Transfer  Transposons