Kartagener Syndrome (Cytoskeleton)
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These are small bead-like sub units that make up Actin
What are “G-actin” monomers assembled into a helical polymer called “F-actin”
Can have a growing (+) and shrinking (-) end: Which end happens when ATP binds to G-actin and which end happens after hydrolysis to ADP?
+ is when ATP binds to G-actin - is after hydrolysis to ADP
What percentage of muscle cell protein is made up of actin?
10% of muscles cells and 1-5% of total protein in non-muscle cells
Myosin is really nothing more than assembled …. ?
Protein motors
T or F: Myosin is an enzyme?
TRUE!!! The head region is the enzyme part; can “walk” on actin by hydrolyzing ATP … thus, also considered protein motors
ATP is used in two ways w/ the myosin head. What are they?
ATP is used to change its conformation, and to set up a “power stroke”
What is it called when Myosin head is bound to Actin?
Rigor Complex
What is the ultimate control of contraction?
temporarily opening Ca++ channels
Which type of receptor releases Ca++ from SER?
Ryanodine receptor (voltage-gated ion channel)
T of F: Myosin can bind to actin when tropomyosin is covering binding site?
True. But it cannot slide on actin until Ca++ is released
Actin and myosin are also in non-muscle cells. Give some examples.
• Contractile ring forming a cleavage furrow to complete telophase • Interior of microvilli • attach cytoskeleton to plasma membrane at anchoring points
Which transmembrane linker anchors to another cell? to an ECM protein?
Cadherin = to another cell Integrin = to an ECM protein
All intermediate microfilaments play a functional or structural role? Actin and myosin play a functional or structural role?
Intermediate = structural role Actin and Myosin = both functional and structural roles
What type of filament is Keratin? Where is it found? What does it do?
Intermediate filament Found in epithelial cells Provides flexibility and resilience
What type of filament is Desmin? Where is it found? What does it do?
Intermediate filament Found in muscle cells Forms Z-lines (links myofibrils together)
Vimentin is found …?
connective tissue cells
What are neurofilaments?
structural proteins in neurons
What are microtubules? What are they made of?
They are protein rods made up of tubulin
Where does addition and deletion happen in a mircrotubule in a living cel?
Both addition and deletion of tubulin dimers happen at the plus end ONLY. The minus end is capped
What does the addition of tubulin on a microtubule require?
GTP-binding. When GTP is hydrolyzed to GDP, the tube shrinks
What is a centrosome?
Collection of 2 microtubules (centrioles)
What arrangement do centrioles have?
9 + 0 arrangement; 9 groups of 3 w/ 0 in middle
What do most microtubules function involve?
Movement (ciliary and flagellar, intracellular transport of vesicles…etc)
What does movement of microtubules require?
Requires “motors” kinesin and dynein, and these motors require the hydrolysis of ATP