Archean Eon lecture notes.doc

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24 Mar 2012
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Archean Eon
Slide 32:
-Archean eon comes from archea
Slide 34:
-cocci = round
-bacilli = rod shaped
-bacteria named was based on size, shape and mobility
-there are too many bacteria now to be named based on morphological differences
-bacteria are now classified based on genome structure
-named using strains (i.e.: strain numbers)
-identifies genomic fingerprint
Slide 35:
bacteria
-very small and simple
-bag of cytoplasm surrounded by phospholipid plasma membrane
-cytoplasm includes ribosomes (for protein synthesis) and nucleus
-nucleus is a single, circular DNA material with no membrane
-DNA is dense in the nucleoid area
-contains circular plasmid
-no compartmentalization (only regions of specialization)
-involves the first forms of life
-diverse forms of metabolism to capture energy
-various types of asexual reproduction
-no internal organelles
-chromosome strand is packaged
-cytoplasm surrounds ribosomes and nuclear material that is contained in a nucleoid made
of packed chromosomes (which stabilizes DNA strand)
-plasma membrane surrounded by non-living cell walls
-cell wall (peptidoglycan layer and the outer membrane) ensures integrity of the cell due to
osmotic issues
-unique spinning flagellum allows for motility
Slide 36:
-gram stains (positive = stained ; negative = didn't stain)
gram positive bacteria:
-cell wall contained by peptidoglycan which is the part that stains (sugar + protein)
-long chain of alternating dimer (2 different) sugar molecules with 4 amino acids
linked to another 4 amino acids on the adjacent chain forming the matrix of the
cell wall
-mesh is formed made up of sugar molecules with 4 amino peptide branches that
are interwoven with other amino acid strands and this gives rigidity to the cell
wall
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-the peptidoglycan is the part that is stained
gram negative bacteria:
-small peptidoglycan layer
-2 plasma membranes (outer and inner bilipid layer)
-cannot stain since peptidoglycan is hidden under lipid layer
-most gram negative bacteria are toxic and pathogenic
-pathogenecity is due to proteins embedded in outer membrane
-capsule (which may or may not be present in bacteria) is equivalent to the glycocalyx
-slime-like surface; important for adhesion to substrates
-not a universal characteristic
-made up of hydrocarbons and is gelatinous
-periplasm surrounds peptidoglycan between membranes
Slide 38:
-flagellum mechanism is unique for bacteria
-made up of 20 proteins
-3 major components of bacterial flagellum:
-flagellum: spinning propeller; polymerized, uniform protein
-hook: ties flagellum to motor
-base: contains the motor
-contains rings which embed motor into the membrane
-ring create a bearing (hole in plasma membrane so hook can spin
with little resistance)
-lipophilic sites to anchor protein into membrane
-rings create hole in plasma membrane so hook can spin with little
resistance
-motor:
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