Bacteria And why they are cool!

Bacteria are prokaryotes (no membrane bound organelles) They are microscopic, ranging in size from 10 to 100 micrometers (There are one million micrometers in a meter. This means that 10 000 can fit end to end along one cm)

Both kingdoms are similar: Bacteria are classified as either Eubacteria (largest kingdom of the 2) or Archebacteria   Both kingdoms are similar: Small Lack nuclei Have cell walls

Major Differences Archebacteria lack peptidoglycan in cell walls Have DNA more like eukaryotes (have nuclei)

Interesting Archebacteria Methanogens produce methane gas Live without oxygen Others can live in very salty environments

Three Shapes Bacilli – rod shape Cocci – spherical Spirilla - corkscrew shape

Ways to Identify Cell walls: Thin (will look pink when stained) Thick (will look purple when stained)

Movement May have flagella (whiplike structures)to propel them along May spiral, or snake, forward May ooze along May not move at all

Metabolic Function: AKA How They Get Their Energy Most are heterotrophs (get energy from other organisms)   Chemoheterotrophs Must take in organic (from living organisms) compounds for energy and carbon  Photoheterotrophs Are photosynthetic and use sunlight for energy, but also need organic compounds for carbon

Others are autotrophs (make their own food) Photoautotrophs Are photosynthetic Use sunlight for all their energy and carbon needs Cyanobacteria: have blue pigment, found around the world on land and in water (near the surface), are often the first species to recolonize an area after natural disaster Chemoautotrophs Do not require sunlight Get all their energy and carbon from other chemicals Can live deep in the ocean

Oxygen requirements Obligate aerobes Obligate anaerobes MUST have oxygen Ex. Mycobacterium tuberculosis  Obligate anaerobes MUST live without oxygen Ex. Clostridium botulinum  Facultative anaerobes Do not require oxygen, but are not killed by it. Ex. Escherichia coli (E. coli)

Growth and Reproduction Binary Fission Bacteria replicates (copies) its DNA and divides in half No exchange of genetic material   Conjugation Hollow tube forms between two bacteria Genes move from one to another Increases genetic diversity

Spore Formation Bacteria can form spores when conditions for living might kill them Endospore: bacterium makes a thick interior wall; saves DNA and some cytoplasm Spores can be dormant for years Ex. Bacillus anthrax

Importance of Bacteria Not all are harmful Good bacteria include: Decomposers - break down dead stuff  Nitrogen fixers – convert nitrogen into a form plants can use

Human Benefits Human benefits: Used to produce foods and beverages (can you think of some?) Digest oil spills Remove wastes and poison from water Mine minerals Help make drugs and other chemicals (by genetic engineering) Make vitamins in our colon (large intestine) New uses being discovered