Cell Bio Exam 2

Front 1

calmodulin

Back 1

the ligth chains of myosin I and myosin V, Ca2+ binding regulatory subunit in many intracellular enzymes

Front 2

myosin head movement

Back 2

caused by a mosin head "walking" toward the + end of a filament; thus filaments move with the (-) end in the lead.
exception is myosin VI

Front 3

neck domains in myosins

Back 3

vary in length and number of associated light chains.
Generally, the longer the neck domain of a myosin, the greater its step size

Front 4

step size

Back 4

the distance traveled along an actin filament in one step

Front 5

cytoplasmic myosins

Back 5

work alone in carrying their membrane cargoes. they move without dissociating from the filaments because of the high duty ratio (they are bound to acitn filaments for most of the ATP cycle).
this means they move along a filament for along distance with little danger of falling off.

Front 6

duty ratio

Back 6

the fraction of time spent attached to the filament during the ATPase cycle.

Front 7

Cytoplasmic Streaming

Back 7

the bulk cytosol is propelled by myosin attached to parts of the ER lying along e stationary atin filaments

Front 8

contractile bundles

Back 8

composed of actin and myosin II filaments.
maybe be transitory or permanent
when isolated from they contract on the addition of ATP
always located adjacent to the plasma membrane as a sheet or belt

Front 9

stress fibers

Back 9

ends terminate at integrin-containing focal adhesions
second type of contractile bundle

Front 10

integrin-containing focal adhesions

Back 10

special structures that attach a cell the the underlying substratum

Front 11

myofibril

Back 11

chains of sacromere about 2 micrometers long in resting muscles

Front 12

sacromere

Back 12

a specialized structure that is both the structural and functional unit of skeletal muscle

Front 13

smooth muscle contraction regulation

Back 13

regulated by cycling of myosin II between no and off states and by Ca2+ levels in response to extracellular signaling

Front 14

Calcium dependent activation of Myosin II

Back 14

when the regulator ight chain is unphosphorylated, myosin II is inactive. the smooth mscle contracts when the regulatory LC is phosphoryated by the enzyme mosin LC kinase.

Front 15

steering of migrating cells by chemotactic molecules

Back 15

some movement is guided by insoluble molecules in the underlying substratum
sometimes the cell senses soluble molecules and follows them, along a concentration gradient, to their source. the latter response is called chemotaxis.