The Prokaryotic World Ch 16.2

Prokaryotes Prokaryote: a cell that lacks a nucleus and other organelles 2 types of prokaryotes: 1. Archaea 2. Bacteria

Archaea “Archaea” means ancient; not bacteria These are some of the oldest life forms on Earth Live in extreme conditions that resemble early Earth –Thermophiles lives in hot spring or sea vents –Halophiles (“salt lover”) lives in salty conditions (Dead Sea, Great Salt Lake) –Some live in oxygen free environments (volcanoes)

Archaea and Bacteria Once considered to be in the same kingdom, genetic analysis of archaea tells us that they are just as closely related to eukaryotes as they are bacteria –Also have structural differences It is believed that archaea and bacteria share an ancient prokaryotic ancestor Given their own Domain (Bacteria, Archaea, Eukaryotes)

Evolution of Bacteria Bacteria are microscopic prokaryotes –Between 0.2 – 6 µm (micrometers ) –Smallest living cells Fossil records indicate that there were bacteria 3.5 billion years ago –Archaea fossils are as old as 4.5 billion yrs old

Classification of Bacteria Bacteria have few morphological features (internal or external structures) Grouped based on structure, physiology (how they work), composition (what they’re made of), and motility

Structure Capsule Cell wall Plasma membrane DNA or RNA Pili Endospore Flagella

Nutrition and Growth Can be producers or consumers (decomposers or parasites) Producers use light (cyanobacteria) or chemicals (sulfur bacteria) to make food Some can live with or without oxygen: –Obligate anaerobes ~ can’t live in O 2 –Facultative anaerobes ~ can live w/ or w/out O 2 –Obligate aerobes ~ can’t live w/out O 2

Naming bacteria First decide what arrangement the colony is in: –Diplo = Pairs –Staphylo = Clusters –Strepto = Chains

Now choose the shape the bacteria is: –Cocci = Round –Bacillus = Rod –Sprillium = Spiral

Naming common bacteria To name common bacteria, we combine arrangement + shape How would you name this bacteria? –STAPHYLOBACILLUS