17 Apr 2012
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Endosymbiotic Organelles, the Cytoskeleton and Cell Junction
Symbiont - two organism depend/live among each other
Endo - inside the cell
Mitochondria
have outer plasma membrane and highly folded inner membrane.
Inner folds have large proteins used in Cellular Respiration.
Contains DNA, RNA and ribosomes.
Chloroplast
In plants, carries out photosynthesis
Part of the "plastids"
Similar to Mitochondria (outer membrane and inner membrane)
They have a stacks of membranes derived from inner membrane - where
proteins and enzymes are found for photosynthesis and carbon fixation.
Own DNA, RNA and ribosomes.
Endosymbiont Theory
At the start of evolution chloroplast/mitochondria were individual cells, since they
have a double membrane and their own DNA/genome and own ribosome (similar
to eubacteria).
Another Cell perhaps "attempted" to engulf it through endocytosis
The cells became symiotic
NOTE:
In General,
The Nucleus, then the Golgi, are most related to the endomembrane system.
The Cell Membrane is not part of the system, but closely related.
The Mitochondria is a separate system.
Cytoskeleton
Maintains Shape and Polarity
Provides locomotion
Can act as a tract for "motor" proteins
Actin Filaments
made of "actin" protein
give shape and structure
together with motor myosin it can mediate cell shape changes, cell migration and
muscle contraction.
exists as monomer in cells and can polymerize to form the filaments
they have a + end and - end
Actin-Myosin Contraction
Myosin - Large Protein w/ head and tail domain
Tail domain forms a coiled coil (2 alpha helices wrapped around) forming a