Chapter 12 (Part 2) Flashcards
what is actin filament made of?
G (globular) actin monomers strung together to make F (fibrous) actin
what is an actin filament?
2 actin fibers twisted together to form an alpha helical actin filament
what do you call 2 actin fibers twisted together to form an alpha helical structure
actin filament
where is tropomyosin found?
found on the myosin binding sites of actin;
wraps around each actin fiber of the actin filament
what is the role of tropomyosin?
covers sites that the myosin thick filament wants to bind to
what is troponin?
a three protein complex
where is troponin found?
periodically found along the tropomyosin and contacts the actin fibers
describe the structure of a thick (myosin) filament
- head with an actin binding site
- ATPase binding site to hydrolyze ATP
- tail
two myosin proteins are twisted together to form a myosin dimer
hydrolysis of ATP puts the _____ head into the ____ energy position
myosin head
high energy
what causes actin filaments to move towards M line
binding to actin
why is it important that crossbridging is not synchronized, myosin heads bind and release at different times.
to maintain some amount of tension, allowing for smooth rather than jerky movements
name one process that contributes to contraction
folding
