Biochemistry
9th Edition
ISBN: 9781319114671
Author: Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.
Publisher: W. H. Freeman
expand_more
expand_more
format_list_bulleted
Question
Chapter 36, Problem 18P
Interpretation Introduction
Interpretation:
The mechanism of ATP hydrolysis in the mechanical working of myosin should be determined.
Concept introduction:
The myosin is a type of motor filaments present in the eukaryotes. It is present in the muscles and help in muscle contraction. They remain bind to the actin in normal circumstances and released during the process of muscle contraction.
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
The ability of myosin to walk along an actin filament may be observed with the aid of an appropriately equipped microscope. Describe how such assays are typically performed. Why is ATP required in these assays? How can such assays be used to determine the direction of myosin movement or the force produced by myosin?
The sliding-filament model of skeletal-muscle contraction assumes a sliding or slipping of interdigitating filaments of actin and myosin. Electron micrographs show that during contraction the actin and my-osin filaments remain of constant length while the distance between Z lines shortens. Explain how this happens in terms of the molecular structure of the muscle filaments. What is the role of regulatory pro-teins (troponin and tropomyosin) in contraction?
Describe the movement of myosin along an actin filament. Outline the primary molecular steps and explain how this process is used by cells. How many actin monomers within an actin filament would a myosin molecule need to ratchet in order to contract a cell by approximately 1 um? How fast could a non-muscle cell make this contraction compared to a muscle cell if the relative rates of myosin walks on F-actin are 4.5 um/sec and 0.04 um/sec for myosin II and I respectively?
Knowledge Booster
Similar questions
- As mentioned in class, one additional major use of ATP in skeletal muscle (besides powering the myosin heads) is the recycling of calcium ions back into the sarcoplasmic reticulum after depolarization. The resting concentration of Ca++ in the muscle cell cytoplasm is about 50-100 nM, and the spike concentration after depolarization is about 10-20 μΜ. a) Consider a single sarcomere. What is the number of free calcium ions within the sarcomere at rest? What is the number of free calcium ions after depolarization? b) The major ion pump responsible for calcium ion recycling is SERCA (sarco/endoplasmic reticulum calcium ATPase). SERCA uses one molecule of ATP to pump two calcium ions, and the resting level can be restored in about 10-20 ms. How many molecules of ATP are used in a single sarcomere for pumping calcium in a single "twitch"? c) Assume that a single "twitch" is sufficient to drive one sarcomere from its fully extended length (about 2.5 µm) to its fully contracted length (about 1…arrow_forwardCertain multi-headed myosins bind cooperatively to actin filaments. The binding interaction is mainly electrostatic in nature, so the presence of additional salt (ions) in solution can interfere with binding; ions will tend to associate with charged residues on the two proteins, blocking electrostatic attractions that would otherwise take place. Briefly describe the expected shape of the binding curve for one of these myosins, and what will happen to the shape when the salt concentration increases.arrow_forwardYou’ve setup an in-vitro experiment to measure molecular motors and have an irreversibly binding ATP analogue. After conducting the experiment, you find that this irreversibly binding ATP analog stops motor function. Explain why that is the case.arrow_forward
- Discuss the steps in the hydrolysis of ATP by myosin and how these steps are coupled to the binding and unbinding of actin, promoting mechanical motion.arrow_forwardMyosin 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?arrow_forwardFor the skeletal muscle, hydrolyzation of ATP: Group of answer choices At the myosin head gives rise to the generation of power stroke. At the actin G-molecule gives rise to the generation of power stroke. At the myosin head give rise to the rotation of myosin head to the "cocked back" position. At the actin G-molecule give rise to the rotation of myosin head to the "cocked back" position.arrow_forward
- You 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_forward96. An investigator is studying the contraction and relaxation of vascular smooth muscle in an experimental animal model. Which of the following describes the most likely order of events during this process? 0000000 200602 H) Myosin Light Chain Phosphorylation 1 2 2 3 3 4 4 Binding of Calcium to Calmodulin 3 1 4 2 4 2 3 Myosin Light Chain Dephosphorylation 2 3 4 3 4 2 1 2 Calcium Entry Into the Cell 4 2 3 1 1 1 3 1arrow_forwardA few hours after the death of an animal, the corpse will stiffen as a result of continued contraction of muscle tissue (this state is called rigor mortis). This phenomenon is the result of the loss of ATP production in muscle tissue. (a) Consult Figure 7.48 and describe, in terms of the six-step model of mus- de contraction, how a lack of ATP in sarcomeres would result in rigor mortis. (b) The Ca* transporter in sarcomeres that keeps the [Ca*)-10-7 M requires ATP to drive transport of Ca* ions across the membrane of the sarcoplasmic reticulum. How would a loss of this Ca* transport func- tion result in the initiation of rigor mortis? (c) Rigor mortis is maximal at - 12 hrs after death, and by 72 hrs is no longer observed. Propose an explanation for the disappearance of rigor mortis after 12 hrs.arrow_forward
- How many actin monomers within an actin filament would a myosin molecule need to ratchet in order to contract a cell by approximately 1 μm?arrow_forwardHow can myosin convert the chemical energy released by ATP hydrolysis into mechanical work?arrow_forwardYou are a brilliant (but evil) biochemist who is developing a toxin that can be used to paralyze skeletal muscle. Using your knowledge of how muscle contraction happens at the cellular and molecular levels, identify two steps in the sequence of events necessary for the contraction that could be disrupted to cause paralysis, and explain why each disruption would prevent muscle contraction.arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Human Physiology: From Cells to Systems (MindTap ...BiologyISBN:9781285866932Author:Lauralee SherwoodPublisher:Cengage Learning
Human Physiology: From Cells to Systems (MindTap ...
Biology
ISBN:9781285866932
Author:Lauralee Sherwood
Publisher:Cengage Learning