Motor Proteins and Directed Movement Along Tracks · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

Tiny walkers on one way tracks

Science · Organisms & Life Processes · ages 20-22
Name ______________________   Date ____________

  1. Kinesin mostly walks toward which end of a microtubule?

    • The minus end
    • Neither end matters
    • The plus end

  2. What does one ATP molecule buy a motor protein?

    • A brand new track
    • Exactly one step
    • A full trip across the cell

  3. Myosin walks on actin while kinesin and dynein walk on microtubules.

    Circle one:   True   False

  4. Someone claims a motor keeps stepping with no fresh ATP at all. What is wrong?

    • Motors never touch fuel
    • ATP only builds tracks
    • Steps consume ATP, so stepping cannot continue without fuel

  5. A vesicle must return from the cell edge to the center on the same microtubule. Which motor does the job?

    • Kinesin
    • Myosin
    • Dynein

  6. Calcium floods a muscle fiber. What happens next?

    • The tracks dissolve away
    • Binding sites open and myosin heads start cycling
    • All motors detach forever

  7. Short local deliveries near the membrane are best assigned to kinesin on microtubules.

    Circle one:   True   False

  8. A cargo must go outward but only dynein is attached. What is the result?

    • It travels inward, the wrong way
    • It travels outward normally
    • It splits into two bags
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Tiny walkers on one way tracks W1-mt_TUTmILr7y0-s1

  1. The plus end · Kinesin is the plus end walker, dynein takes the minus end.
  2. Exactly one step · The cycle couples one fuel molecule to one single stride.
  3. True · That split is the strict division of labor in the cell.
  4. Steps consume ATP, so stepping cannot continue without fuel · Each stride spends one ATP, so the walking must halt.
  5. Dynein · The inward trip toward the minus end belongs to dynein.
  6. Binding sites open and myosin heads start cycling · Calcium uncovers the sites, and the myosin crew starts rowing.
  7. False · Local actin work belongs to myosin, and kinesin is the long haul motor.
  8. It travels inward, the wrong way · Dynein walks toward the minus end, which points inward here.
Worksheet · LightMySky