BIOCHEMISTRY BOOKS ALC&MOD MST/ET PKG
1st Edition
ISBN: 9780134172507
Author: APPLING
Publisher: Pearson Education
expand_more
expand_more
format_list_bulleted
Concept explainers
Videos
Textbook Question
Chapter 7, Problem 15P
A 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 roof mortis). This phenomenon is the result of the loss of ATP production in muscle tissue.
a. Consult Figure 7.482 and describe, in terms six-step model of muscle contraction, how a lack of ATP in sarcomeres would result in rigor mortis.
b. The Ca2+ transporter in sarcomeres that keeps the [Ca2+] ~ 10-7 M requires ATP to drive transport of Ca2+ ions across the membrane of the sarcoplasmic reticulum. How would a loss of this Ca2+ transport function result in the initiation of rigor mortis?
c. Rigor mortis s maximal at ̀´ 12 hrs after death by 72 hrs is no longer observed. Propose an explanation for the disappearance of rigor mortis after 12 hrs.
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
A 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.
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…
A.What is the Result of the sodium potassium ATPase activity in the cell?
B.What mechanism does the sodium potassium ATPase use to achieve this result?
C. Why is the above-mentioned change in affinity critical for the sodium potassium ATPase to perform its function?
Chapter 7 Solutions
BIOCHEMISTRY BOOKS ALC&MOD MST/ET PKG
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biochemistry and related others by exploring similar questions and additional content below.Similar questions
- During the cross-bridge in muscle cells, myosin motors hydrolyzes ATP as a fuel to create a pulling force on actin fibers. Please describe1) the myosin motors undergo different steps of ATP hydrolysis2) the state of the ATP nucleotide affects the binding and position of the myosin motor with respect to the actin fiberarrow_forwardThe contraction of cardiac muscle cells results from the increase in calcium ion levels in the cytosol. For the cells to relax, an antiport removes calcium ion from the cytosol for every sodium ion that is taken in. Digitalis is a drug that is used to make the heart contract more strongly. This drug partially inhibits the Na+-K+ ATPase in the cardiac cells. Applying the concepts about membrane transport, answer the following: a. Propose an explanation for the drug’s effect.b. What will likely happen if too much of the drug is taken in? Why?arrow_forwardThe contraction of cardiac muscle cells results from the increase in Ca?+ levels in the cytosol. For these cells to relax, an antiport removes Ca?+ from the cytosol for every Nat that is taken in. Digitalis is a drug that is used to make the heart contract more strongly. This drug partially inhibits the Na*-K* ATPase in the cardiac cells. Applying the concepts from membrane transport, answer the following: a. Propose an explanation for the drug's effect. b. What will likely happen if too much of the drug is taken in? Why do you say so?arrow_forward
- Cardiac and skeletal muscle are both “striated” types of muscle and yet they have very distinct functional characteristics. a) Skeletal muscle functions as discrete motor units and the cardiac muscle works as a functional syncytium. Define the italicized terms in the previous sentence, explain their importance, and describe the cellular features that underlie these functional differences. b) Cardiac muscle exhibits automaticity, while excitation of skeletal muscle is neurogenic. Define the italicized terms and provide a brief explanation of mechanisms underlying each.arrow_forwardWhich of the following is true concerning the role of Calcium in the contraction of muscle- cells? 23. A. skeletal muscle cells require an extracellular inward-Calcium-current to stimulate the burst of Calcium from the sarcoplasmic reticulum. B. smooth muscle cells require an extracellular inward-Calcium-current to stimulate the burst of Calcium from the sarcoplasmic reticulum. C. cardiac muscle cells require an extracellular inward-Calcium-current to stimulate the An burst of Calcium from intracellular stored-Calcium-organelles. D. No type of muscle cell requires an extracellular inward-Calcium current for normal contractile-function.arrow_forwardIn active muscle cells, the pO₂ is about 10 torr at the cell surface and 1 torr at the mitochondria (the organelles where oxidative metabolism occurs). Calculate the percentage of bound oxygen transported to the mitochondria of muscle cells by myoglobin (KD = 2 torr). A new oxygen transport protein that exhibits cooperative binding has been isolated and is being studied in the lab. Calculate the Ko value if Y = 0.76 when pO₂2 = 18 torr (assume n = 2.5). How does this compare to the K₂ value for hemoglobin? Does this protein bind more or less tightly to oxygen compared to hemoglobin?arrow_forward
- Shortly after a person dies, Ca2+diffuses out of the saroplasmic reticulum and the body becomes very still and rigid, a phenomenoncalled rigor mortis (rig′er mōr′tis). Given ATP’s role in myosin head movement, propose an explanation for rigor mortis.arrow_forwardContraction of both skeletal and smooth muscle is triggered by an increase in cytosolic Ca2+. Compare the mechanisms by which each type of muscle converts a rise in Ca2+ concentration into contraction.arrow_forwardOne of the effects of low oxygen levels in cardiac cells is arise in cytoplasmic calcium levels as a result of the depressedactivity of the plasma membrane’s Ca2+-ATPase. What aresome of the consequences of this phenomenon?arrow_forward
- The sarcoplasmic reticulum Ca2+-ATPase, pumps 2 mol Ca2+ out of sarcomeres per mol ATP hydrolyzed. Part A: Given the following steady-state concentrations and a membrane potential of 64 mV (inside negative), calculate ΔG for the following active transport process at 37 ∘C and pH=7.4: 2Ca2+(in)+ATP+H2O→2Ca2+(out)+ADP+Pi+H+ ATP=2.8mM,ADP=206μM,Pi=5.4mM,Ca2+(in)=34μM,Ca2+(out)=2.2mM The answer to part A was -7.4 kJ/mol I need help with Part B: Part B: The activity of the Ca2+-ATPase is regulated reversibly under normal conditions to maintain homeostatic concentrations of Ca2+ inside the sarcomere. However, in a rare genetic disorder, irreversible activation of the Ca2+-ATPase can occur. Assuming 37 ∘C, pH=7.4, and the steady-state concentrations for ATP, ADP Pi, and Ca2+(out) given in part (a) calculate the minimum [Ca2+] inside a sarcomere that has irreversibly activated Ca2+-ATPase (i.e., the Ca2+-ATPase activity is always “on”).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 the sequence of cellular/molecular events that cause a muscle contraction, identify two parts of the process that could be disrupted to cause paralysis, and explain the specific effect of each disruption on contraction. please helparrow_forwardDetermine whether the following statement regarding the mechanism of the SERCA pump is TRUE (T) or FALSE (F). 1. In the E1 conformation, the two Ca2+-binding sites are exposed on the luminal side of the ER or sarcoplasmic reticulum. 2. ATP binding alone drives a conformation change from E1 to E2.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
7 Freudian Defence Mechanisms Explained; Author: Lewis Psychology;https://www.youtube.com/watch?v=fTnjJ105ze4;License: Standard youtube license