Becker's World of the Cell (9th Edition)
9th Edition
ISBN: 9780321934925
Author: Jeff Hardin, Gregory Paul Bertoni
Publisher: PEARSON
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Chapter 14, Problem 14.5CC
In addition to being found at the rear of migrating cells, nonmuscle myosin II is also typically found in cellular protrusions, where it “reels in” actin at the base of lamellipodia. Based on what you know about the direction in which myosin II moves along actin and the polarity of actin filaments in lamellipodia, why does myosin have this effect on the actin in lamellipodia?
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When ADP and Pi are bound to myosin in the cross-bridge cycle... (MULTIPLE SELECT)
A. There is no force production and myosin is not bound to actin
B. There is no force production and myosin is bound to actin
C. There is force production and myosin is not bound to actin
D. If its smooth muscle, a second phosphate might be bound to the light chain
E. The cross-bridge is in a state of rigor mortis
F. There is force production and myosin is bound to actin
What does ATP binding to myosin head triggers?
a.
Its association with microtubules
b.
Its dissociation from actin microfilament
c.
Conformational change and rotation of myosin head
d.
Its association with actin microfilament
Myosin II has a duty ratio of 10 percent, and its step size is 8 nm. In contrast, myosin V has a much higher duty ratio (about 70 percent) and takes 36-nm steps as it walks down an actin filament. What differences between myosin II and myosin V account for their different properties?
Chapter 14 Solutions
Becker's World of the Cell (9th Edition)
Ch. 14 - If myosin V moved more like an inchworm (meaning...Ch. 14 - Kinesins and dyneins are both microtubule-based...Ch. 14 - CONCEPT CHECK 14.2 Human sperm swim using a...Ch. 14 - A single myosin II motor domain can exert about 15...Ch. 14 - Prob. 14.4CCCh. 14 - In addition to being found at the rear of...Ch. 14 - Ciliobrevins. Ciliobrevins were reported in 2012...Ch. 14 - Prob. 14.2PSCh. 14 - Prob. 14.3PSCh. 14 - Rigor Mortis and the Contraction Cycle. After...
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.Similar questions
- Rigor mortis occurs following death because a. tropomyosin remains over the myosin binding sites of actin. b. myosin heads attach to actin and are not released due to lack of ATP. c. the myosin becomes misshapen. d. all of the Ca2+ remains within the sarcoplasmic reticulum.arrow_forwardChoose the best description of how myosin and actin are arranged within the two types of protein filaments in myofibrils. a.) Actin makes up the think filaments, and myosin makes up the thin filaments. b.) Myosin makes up the think filaments, and actin makes up the thin filaments. c.) Myosin and actin are randomly interspersed in the think filaments but are absent from the thin filaments. d.) Myosin and actin overlap with each other to make up both the think and thin filaments.arrow_forwardWhich of these statements about the molecular structure of myofilaments is true?a. Tropomyosin has a binding site for Ca2+.b. The head of the myosin molecule binds to an active site on G actin.c. ATPase is found on troponin.d. Troponin binds to the rodlike portion of myosin.e. Actin molecules have a hingelike portion, which bends and straightensduring contraction.arrow_forward
- With regard to muscle contraction, which of the following is an INCORRECT statement with regard to the interactions of filaments that occur in the sarcomere? A. When muscles are relaxed tropomyosin blocks binding sites on actin subunits, which keeps cross-bridges from forming. B. The myosin heads conduct a power stroke motion to slide when bound to actin, to move the "thin" filaments towards the center of the sarcomere. C. During contraction, actin subunits are removed from the ends of the "thin" filaments to shorten actin polymers, thus reducing the length of the sarcomere. D. "Thick" filaments are anchored at the M-line, while "thin" filaments are anchored at the Z-line. E. Numerous myosin heads engage with the actin filaments simultaneously, such that there is no back-slipping during the contraction process.arrow_forwardA typical relaxed sarcomere is about 2.3 μm in length and contracts to about2 μm in length. Within the sarcomere, the thin filaments are about 1 μmlong and the thick filaments are about 1.5 μm long.(a) Describe the overlap of thick and thin filaments in the relaxed and contracted sarcomere.(b) An individual “step” by a myosin head in one cycle pulls the thin filamentabout 15 nm. How many steps must each actin fiber make in one contraction?arrow_forwardYou know from experience that skeletal muscle tires quite quickly, especially if there is not enough oxygen. Interestingly, shellfish such as clams can maintain a month-long contraction in the muscle that keeps the shell closed. No oxygen gets in this situation. These muscles have a different version of myosin called paramyosin. Knowing what you know about the cellular mechanism of muscle contraction, propose a hypothesis to explain how paramyosin might work.arrow_forward
- In bending in the binding of the myosin head of the free binding site of the actin filament results in the contraction of the musclearrow_forwardWhere is ATP's energy used during crossbridge cycling? A. When ATP attaches to myosin and causes myosin to pull on actin ("pull" step) B. When ATP attaches to myosin and causes myosin to attach to actin ("grab" step) C. When ATP splits and pushes myosin back into the "cocked" position ("reset" step) D. When ATP attaches to actin and causes actin and myosin to separate ("release" step)arrow_forwardA mutation has occurred that prevents ATP from binding from the heads of myosin. What impact would this have (if any) on human muscle contraction? Select one: a. ATP has no impact on myosin binding. Myosin, unlike kinesins, works with GTP. b. Without ATP, myosin will be stuck to microfilaments, causing muscles to be “stuck” in whatever position they were last in. c. Without ATP, myosin will not be able to bind to microtubules and move vesicles or chromosomes around the cell resulting in cell death. d. Without ATP, myosin will be stuck to intermediate filaments “locking” organelles in place in the cell.arrow_forward
- The sliding filament model depicts how myosin motors attached to actin lead to muscle contraction. This process proceeds in a precise series of events. Indicate which of the following shows the correct order of steps in the sliding filament model. Group of answer choices Myosin binds ATP; myosin tightly binds actin; power stroke; myosin releases actin Myosin binds GTP; myosin releases actin; power stroke; myosin tightly binds actin Actin binds ATP; power stroke; myosin tightly binds actin; actin releases ADP Actin binds ADP; myosin releases actin; power stroke; actin releases ADParrow_forwardThe following list of events take place during a muscle contraction. Place the events in chronological order as they relate to a muscle contraction. Calcium is released from the sarcoplasmic reticulum. Myosin heads bind to actin. An action potential arrives at the axon terminal of a motor neuron. Calcium binds to troponin, displacing tropomyosin and exposing myosin head binding sites on actin. Myosin heads undergo power stroke and actin slides over myosin towards M line of sarcomere. Acetylcholine is released at the neuromuscular junction.arrow_forwardThere are at least 20 different types of myosin. What properties do all types share, and what makes them different?arrow_forward
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