Download Cytoskeleton, Cell Connections, ECM

Cytoskelton, Cell Connections, ECM
Cytoskeleton: structure (support), motility, movement
- stabilizes animal cells by balancing opposing forces.
- Anchorage of other organelles
- Vesicles move along cytoskeleton as they move to plasma
membrane or other organelles (endomembrane system).
TYPES:
1. microtubules: hollow rods of tubulin protein subunits.
- Can disassemble their tubulin and reassemble to assist in
a cell changing shape
 Specific functions:
1. Maintenance of cell shape (compression bearing).
2. Cell motility (cilia and flagella)
3. Chomosomal movement
4. Organelle movement
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Specific example #1
• cillia and flagella:
- responsible for locomotion of motile cells (sperm,
protists)
Example #2:
• framework for organelle attachment
- guide for motion of organelles and proteins via motor
proteins attached to membrane of organelles.
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2. Microfilaments:
Specific functions:
1. Maintenance of cell shape (tension-bearing)
2. Changes in cell shape
3. Muscle contractions (actin and myosin proteins… more
later…)
4. Cell division
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3. Intermediate Filaments:
- More or less permanent structures – don’t disassemble
and reassemble like microtubles and microfilaments
 Specific functions:
1. Maintenance of cell shape (tension-bearing)
2. Anchors nucleus (and other organelles)
3. Forms nuclear lamina
Cell Connections
Cells are organized into tissues and need to communicate
so the tissue can function as a single unit.
PLANT CELLS
 plasmodesmata: channels of cytoplasm through plant cell
walls; connects the chemical environment of adjacent cells.
 Macromolecules can move along the
cytoskeleton of a cell, move through
plasmodesmata into adjacent cell.
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ANIMAL CELLS
 desmosomes: fix animal cells together
 tight junctions: also hold animal cells together
but form barrier to travel of extra-cellular fluids
ex. Don’t want HCl leaking out of stomach to abdominal
cavity!
 gap junctions (protein channels): cytoplasmic passages
between animal cells; ions, sugars, and amino acids can
move through…
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 Extracellular Matrix (ECM) = all the structures (stuff)
between 2 cells
- Structure: Proteins, Glycoproteins (w/specific carb shape &
protein structure), fluid between neighboring cells
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- Functions:
o Communication between a cell and its environment
o Regulatory:
 Effects development - Specificity of glycoproteins
for each specialized cell type help to grow and
develop specific tissues with specific jobs
(developing embryo)
 Effects gene expression; therefore, the making of
proteins.
Animal Cells
Collagen – most abundant glycoprotein in animal cells.
Structural support for connected cells
Fibronectin – glycoproteins that connect to proteins embedded in
plasma membrane (through entire thickness) (integrins);
o Integrins are further connected to the cytoskeleton
attached to the inner side of the membrane.
o This connection between Fibronectin (ECM) to integrins
(through plasma membrane) to cytoskeleton helps cell
communicate what is going on outside the cell to the
inside and vise versa.
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