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Cytoskeleton and Cell Motility
8/26/11 First Lecture
10
Medical
Graduate
08/30/2011

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Cards

Term
What are the three major types of cytoskeleton in epithelial cells?
Definition
1. Microtubules
2. Intermediate filaments
3. Actin filaments
Term
Describe the use of intermediate filaments in determining the origin of tumors
Definition
Different types of cells express different types and combinations of intermediate filaments. Examining the IF composition in a tumor can be useful in determining where it originated.
Term
What is the main role of intermediate filaments?
Definition
Structural support in cells
Term
what are the 4 sub classes of IFs and where is each found?
Definition
1. Keratins - epithelia
2. Vimentin - connective tissue, muscles, neuroglial cells
3. Neurofilaments - nerve cells
4. Nuclear lamina - all nucleated cells
Term
Where do intermediate filaments bind to the membrane of epithelial cells and what 2 roles does this play?
Definition
A) desmosomes and hemidesmosomes

B) 1. Dispersion of force 2. Mechanochemical sensing
Term
What are the 3 broad class of functions of actin filaments?
Definition
1. Anchors
2. Stability
3. Motility
Term
Describe the polarity of actin thin filaments
Definition
1. + and - ends
2. - end is pointed, + end is "barbed"
3. + end grows (polymerizes) faster then - end
4. Myosin motors migrate from the - toward the + end
Term
Describe how actin can cause movement in the absence of motor such as myosin
Definition
If the - end is anchored within a cell membrane, addition of units to the + end cause the cell to grow outward into a lemellopedia if the + end reaches and pushes on a cell membrane
Term
What are the 3 parts of a myosin fiber?
Definition
1. head
2. neck
3. tail
Term
Describe the process of myosin motors moving along actin filaments
Definition
1. Nucleotide binding - Binding of ATP to a myosin head causes the head to be released from an actin subunit
2. Hydrolysis - Hydrolysis of ATP to ADP causes pivoting of the head and binding to the next subunit toward the + end
3. P release - Release of the phosphorus group causes the head to pivot and move the actin filament
4. ADP release - ADP is released from the myosin head, allowing the process to begin again
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