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 organellesMany 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

Consumersdepend 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 (O2)

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…

Reproductionbacterial

cell

DNA replicates

DNA splits

Cell wall pinches

two newgenetically

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