Cytoskeleton
“The harder the conflict, the more glorious the triumph.”
Thomas Paine... “Unless you really just screw up.” Bush
1. What are microfilaments?
(He said know how to identify/draw these) Note: since it is multiple choice, I doubt we will have to know how to draw them. **There are also short essay questions and, in past classes, he has asked students to draw. I thought the final was ALL MULTIPLE CHOICE???********************************
Microfilament- Analogous to actin microfilaments. Helical polymer of actin protein; two protofilaments. Smallest cytoskeleton diameter (3-6nm) structure Thinner, shorter, more flexible than microtubes. One basic 7subunit, globular actin. Structurally polar. Have fast reaction to stimuli.
What super structures do they form?
1.Microvilli; structure of microfilaments lining the edge of cell
2.Stress fibers; antiparallel of actin bundles, contractile forces, wound healing ect.
3.Lamellipodia; sheet lik1.Nucleating proteins; Arp2/3 ce projections for movement, actin bundles parallel to cell surface- Same category as Filopodia
4.Filopodia; hair-like extensions or movement and sensory
5.Contractile ring; to help split cells
What other proteins do actin and microfilaments interact with? * complex help in nucleation of microfil., polymerization/ depolymerization, interaction with cell components
What kinds of microfilamentous structures does each protein help form? 1. Bundling protein; F-actin is org. into diff. assemblies based on cross linking proteins 1. Contractile Bundles- Associated protein-Myosin 2 that always moves to + end of F-actin, Non-structurally polar (even tho F-actin is polar by itself), Function-contractions, motility, ect., examples- stress fibers, contractile ring 2. Non-Contractile Bundles- Arranged in tight bundles and sheets, Structurally polar. Formed at the cell’s surface. Increase surface area.