Transcript Unit 4: Microscopes, Cell Structures and tree of Life

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