Prokaryotes Honors Biology Monkemeier

 Microfossils are fossilized forms of microscopic life.  The oldest microfossils are approximately 3.5 billion years old.  The microfossils resemble modern day Archeabacteria.  Modern Archeabacteria live in extreme conditions and early Earth was harsh and was extreme.

 In addition to microfossils, indirect evidence for ancient life can be found in the form of sedimentary deposits called stromatolites.  Stromatolites provide evidence that photosynthetic bacteria were on the Earth approximately 2.5 billion years ago.  The cyanobacteria are also known as blue-green algae.

 Prokaryotes are divided into two Domains, the ARCHAEA and the BACTERIA.

 ALL cells whether prokaryotic or eukaryotic share three features:  Plasma membrane: a cell membrane that acts as a barrier to the exterior environment.  Centrally located genetic material known as DNA. In prokaryotes the DNA is a single, circular structure. In eukaryotes, the DNA has associated proteins, is linear and occur in even numbers.  Cytoplasm: The area between the plasma membrane and fills the interior of the cell. It has a jello-like consistency and can move. The liquid portion minus the organelles is the cytosol.

 Some prokaryotes move by rotating flagella.  Flagella are long, threadlike structures protruding from the surface of the cell that are used in locomotion.  Bacteria can swim at speeds of up to 70 cell lengths per second by rotating their flagella like screws.  The rotary motor uses the energy stored in a gradient that transfers protons across the plasma membrane to power the movement of the flagellum.

ARCHAEA  Amino acid that initiates synthesis: methionine  Cell wall: not composed of peptidoglycan  Cell membrane: Monolipid bilayer  Noncoding regions known as introns in the genes BACTERIA  Amino acid that initiates synthesis formyl-methionine  Cell Wall consists of peptidoglycan  Cell membrane is a phospholipid bilayer  Genes do not contain noncoding regions.

 Archaea bacteria are found in extreme conditions. Early Earth was hostile and extreme. Methanogens, Halophiles, Thermophiles, acidophiles.  Archaea are anaerobic:  Bacteria are found in water, soil and air.

 Bacteria come in three basic shapes.

 Bacteria have a simple cell structure.  Bacteria can be classified by their  Shape  If they contain or do not contain flagella  If they have flagella, the number and positions of the flagella.  Reaction to Gram Staining Technique