Week 8
Major concept goals
-Dynamic instability of a microtubule is due to the GTPase activity of tubulin
-How dynamic instability plus MT stabilizing and destabalizing factors can control the formation of a MT array
-Dynein promotes sliding of MTs in the axoneme to cause cilia bending and cell swimming
-ARPs promote actin nucleation in cells
-At equilibrium actin microfilaments have equal rates of assembly and disassembly from each end leading to tread milling behavior
-The 4 steps of cell crawling
-How actin polymerization is the "motor" that leads to membrane protrusion during cell crawling
Overview of content
I. Building the microtubule (MT) array that mediates cell swimming
A. MTs have structural polarity
B. What is happening during the plateau: Dynamic instability in vitro and in vivo
C. Harnessing the creative energy of dynamic instability to create a MT array
II. Cell swimming
A. Axoneme structure
B. Axoneme function
C. MT motors: dynein and kinesins
D. Mechanism of axnoneme bending
III. Intracellular movement of organelles
A. Melanosome movement
IV. Cell crawling
A. Examples of cell crawling in development and in the immune system
B. Actin assembly into microfilaments
1. Nucleation by Arp2/3
2. Treadmilling of microfilaments at equilibrium
C. The 4 steps of cell crawling
D. Extending the cell membrane forward
1. Lamellipodium
2. Structure and function of actin in the lamellipodium