Harvey Lodish, Arnold Berk, Chris A. Kaiser
ISBN #9781464183393
8th Edition
406 Questions
Homework Questions
The chapters detail the dynamic nature of the actin cytoskeleton and its regulation through multiple actin-binding proteins that coordinate polymerization, depolymerization, and treadmilling. Myosin motor proteins convert the energy of ATP hydrolysis into mechanical work via a power stroke mechanism, with different classes (myosin II in muscle contraction vs myosin V in cargo transport) tailored to specific cellular functions. Additionally, cell migration is orchestrated by spatially regulated signaling pathways involving Rho family GTPases, which help establish cell polarity and direct motile processes such as chemotaxis.
1
-
2
2.
3
E
4
x
5
p
CONCEPT
DEFINITION
Biomembrane Structure
The organized, selectively permeable barrier of the cell composed primarily of amphipathic phospholipids, cholesterol, and proteins, which self?assembles into a lipid bilayer. These structures regulate membrane fluidity, thickness, and the assembly and function of integral and peripheral membrane proteins.
Three systems of cytoskeletal filaments exist in most eukaryotic cells. Compare them in terms of composition, function, and structure.
Actin filaments have a defined polarity. What is filament polarity? How is it generated at the subunit level? How is filament polarity detectable?
In cells, actin filaments form bundles or networks. How do cells form such structures, and what specifically determines whether actin filaments will form a bundle or a network?
Much of our understanding of actin assembly in the cell is derived from experiments using purified actin in vitro. What techniques can be used to study actin assembly in vitro? Explain how each of these techniques works. Which of these techniques would tell you whether the mass of actin filaments is made up of many short actin filaments or fewer longer filaments?
The predominant forms of actin inside a cell are ATP-G-actin and ADP-F-actin. Explain how the interconversion of the nucleotide state is coupled to the assembly and disassembly of actin subunits. What would be the consequence for actin filament assembly/disassembly if a mutation prevented actin's ability to bind ATP? What would be the consequence if a mutation prevented actin's ability to hydrolyze ATP?