Motor mechanisms II
Review questions
Binding of ATP to myosin head causes:
a) actin filament to slide
b) Myosin head to detatch from actin filament
C) Myosin head to cock
What will happen when ADP and Pi dissociate from myosin head?
A) head will detatch from actin filament
B) head will retract and pull actin filament
C) head will bind ADP again
Ca++ induces muscle contraction by:
A) Causing actin monomers to assemble into a filament
B) making ATP available to bind to myosin head
C) allowing myosin head to bind to actin filament
Muscle fiber types are the result of different types (isoforms) of myosin
Type I - slow fibers (aerobic)
Type II - fast fibers (anaerobic)
Type IIx - very fast
Type IIa - intermediate between II x and I
Characteristics of other muscle types:
Cardiac muscle - found only in the heart, striated, gap junctions allow direct electrical signaling between cells
Smooth muscle - involuntary muscle, meshwork of actin and myosin, can contract more (greater shortening), but with less tension.
Muscle cell types schematic:
1) skeletal
2) cardiac
3) smooth
Skeletal muscle
Cardiac
muscle
Smooth muscle