9. You are studying the molecular behavior of myosin II, S1 fragments (including the head and neck domains). You have already repeated classic experiments in which Actin filaments are observed to slide over a coverslip coated with S1 fragments. You have identified a mutation in myosin II that causes it to bind, but not hydrolyze ATP. You bind the mutant myosin II S1 fragments to a coverslip, and add stabilized, labeled Actin filaments and ATP. What happens? a. the actin is hydrolyzed b. the actin filaments stretch out c. the actin does not bind d. the actin binds but does not move e. the actin binds and slides around 10. Proteins that accelerate the polymerization of actin filaments are called a. nucleating proteins d. nucleons b. monomer- sequestering proteins e. cross-linking proteins c. end-blocking proteins 11. When an animal dies, its muscles stiffen for a few hours in a condition called rigor mortis. How is this explained at the level of the sarcomere? a. Muscle myosin requires ATP binding to release the thin actin filaments. Because ATP is no longer being made, myosin and actin remain bound. b. Muscle myosin requires ATP hydrolysis to release the thin actin filaments. Because ATP is no longer being made, myosin and actin remain bound. c. Muscle myosin requires ADP binding to release the thin actin filaments. Because ATP is no longer being made, it also cannot be hydrolyzed, so myosin and actin remain bound. d. Actin filaments require ATP for stablization, so the lack of ATP causes them to shrink. This, in turn, causes muscle contraction. e. Actin filaments require ATP for elongation, so the lack of ATP causes them to shrink. This, in turn, causes muscle contraction. 12. Place the following events for cell locomotion in order: 1) The cell breaks its rear contacts with the substratum, retracting its trailing edge. 2) A part of the cell surface protrudes in the direction of cell movement. 3) Lower surface of cell protrusion attaches to substratum, forming temporary anchorage sites. 4) The bulk of the cell is pulled forward over adhesive contacts..

1. 9. You are studying the molecular behavior of myosin II, S1 fragments (including the head and
neck domains). You have already repeated classic experiments in which Actin filaments are
observed to slide over a coverslip coated with S1 fragments. You have identified a mutation in
myosin II that causes it to bind, but not hydrolyze ATP. You bind the mutant myosin II S1
fragments to a coverslip, and add stabilized, labeled Actin filaments and ATP. What happens? a.
the actin is hydrolyzed b. the actin filaments stretch out c. the actin does not bind d. the actin binds
but does not move e. the actin binds and slides around 10. Proteins that accelerate the
polymerization of actin filaments are called a. nucleating proteins d. nucleons b. monomer-
sequestering proteins e. cross-linking proteins c. end-blocking proteins 11. When an animal dies,
its muscles stiffen for a few hours in a condition called rigor mortis. How is this explained at the
level of the sarcomere? a. Muscle myosin requires ATP binding to release the thin actin filaments.
Because ATP is no longer being made, myosin and actin remain bound. b. Muscle myosin
requires ATP hydrolysis to release the thin actin filaments. Because ATP is no longer being made,
myosin and actin remain bound. c. Muscle myosin requires ADP binding to release the thin actin
filaments. Because ATP is no longer being made, it also cannot be hydrolyzed, so myosin and
actin remain bound. d. Actin filaments require ATP for stablization, so the lack of ATP causes
them to shrink. This, in turn, causes muscle contraction. e. Actin filaments require ATP for
elongation, so the lack of ATP causes them to shrink. This, in turn, causes muscle contraction. 12.
Place the following events for cell locomotion in order: 1) The cell breaks its rear contacts with the
substratum, retracting its trailing edge. 2) A part of the cell surface protrudes in the direction of cell
movement. 3) Lower surface of cell protrusion attaches to substratum, forming temporary
anchorage sites. 4) The bulk of the cell is pulled forward over adhesive contacts.