Sliding Filament Theory and the Sacromere quiz #2 Flashcards
Sliding Filament Theory and the Sacromere quiz #2
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Which region of a sarcomere contains thin filaments?
The I-band contains thin filaments. What is the H band of the sarcomere?
The H band is the region in the center of the A band where there is only myosin and no overlapping actin. What changes occur in the sarcomere during muscle contraction?
During muscle contraction, the sarcomere shortens, the H-zone decreases, and the overlap between actin and myosin increases. What is the H zone?
The H zone is the central region of the A band where there is only myosin and no overlapping actin. Which of the following best describes the term Z line? A) The line marking the center of the sarcomere B) The line marking the end of the sarcomere C) The line marking the start of the A band D) The line marking the start of the I band
B) The line marking the end of the sarcomere A myosin head binds to which molecule to form a cross bridge?
A myosin head binds to actin to form a cross bridge. Which of the following events will not occur within the sarcomeres of a contracting muscle fiber? A) Increase in overlap between actin and myosin B) Shortening of the sarcomere C) Lengthening of the H-zone D) Decrease in the I-band
C) Lengthening of the H-zone Which region of the sarcomere gives rise to the structure (band or line) indicated by the arrow?
The Z-disc gives rise to the structure marking the end of the sarcomere. What is the role of tropomyosin in muscle contraction?
Tropomyosin blocks the myosin binding sites on actin, preventing contraction until it is moved by troponin. What is a sarcomere and Z-line?
A sarcomere is the smallest functional unit of muscle contraction, and the Z-line marks the boundary of each sarcomere. Which of the following is most directly required to initiate the coupling of myosin to actin? A) ATP B) Calcium ions C) Troponin D) Tropomyosin
B) Calcium ions What is the smallest functional unit of a muscle contraction?
The smallest functional unit of a muscle contraction is the sarcomere. What causes the release of myosin heads from actin filaments after the power stroke?
The binding of ATP to the myosin head causes it to release from actin after the power stroke. According to the sliding filament model, what happens during muscle contraction?
According to the sliding filament model, actin and myosin filaments slide past each other, increasing overlap and shortening the sarcomere. Which of the following statements regarding the sliding filament model is false? A) Actin and myosin filaments change length B) Sarcomeres shorten C) Overlap between filaments increases D) Myosin heads pull on actin
A) Actin and myosin filaments change length What is the functional unit of muscle contraction?
The functional unit of muscle contraction is the sarcomere. The sliding filament theory explains how muscles contract. Which of the following explains this? A) Filaments change size B) Filaments slide past each other C) Filaments remain stationary D) Filaments detach completely
B) Filaments slide past each other What causes the myosin head to release its attachment to actin?
The binding of ATP to the myosin head causes it to release its attachment to actin. In a sarcomere, what is the role of the Z-disc?
In a sarcomere, the Z-disc anchors the actin filaments and marks the boundary of the sarcomere. In a sarcomere, what is the role of the M-line?
In a sarcomere, the M-line anchors the myosin filaments in the center. What is the sliding filament model of muscle contraction?
The sliding filament model of muscle contraction describes how myosin heads pull actin filaments towards the center of the sarcomere, causing it to shorten. Which two proteins slide past each other in the sliding filament theory of muscle contraction?
In the sliding filament theory, actin and myosin proteins slide past each other. Which of the following regions of a sarcomere contain thin filaments? A) I-band B) A-band C) H-zone D) M-line
A) I-band Which area of a sarcomere only contains thick filaments?
The H-zone of a sarcomere only contains thick filaments. Which of the following occurs during cross bridge cycling? A) Myosin heads bind to ATP B) Myosin heads bind to actin C) Actin filaments change length D) Myosin filaments change length
B) Myosin heads bind to actin How/when does the myosin head cock back to store energy for the next cycle?
The myosin head cocks back to store energy for the next cycle when ATP is hydrolyzed to ADP and inorganic phosphate. What is found in the I-bands of sarcomeres?
The I-bands of sarcomeres contain only thin filaments (actin). What is found in the A-bands of sarcomeres?
The A-bands of sarcomeres contain overlapping thick (myosin) and thin (actin) filaments. What happens to a sarcomere during a myosin power stroke?
During a myosin power stroke, the sarcomere shortens as the myosin heads pull the actin filaments towards the center. Which of the following describes the sarcomere? A) The area between two M-lines B) The area between two Z-discs C) The area between two A-bands D) The area between two I-bands
B) The area between two Z-discs Where in a sarcomere do you find titin and tropomyosin?
Titin is found spanning from the Z-disc to the M-line, while tropomyosin is found wrapped around actin filaments. The interaction between which protein and ion initiates muscle coupling?
The interaction between troponin and calcium ions initiates muscle coupling. What is a myosin filament shaped like?
A myosin filament is shaped like a thick filament with heads extending outward. What is the term applied to the functional zone between the Z lines in skeletal muscle tissue?
The term applied to the functional zone between the Z lines is the sarcomere. Which of the following proteins makes up the thick filament of the sarcomeres? A) Actin B) Myosin C) Troponin D) Tropomyosin
B) Myosin Which occurs according to the sliding filament theory of contraction?
According to the sliding filament theory, actin and myosin filaments slide past each other, increasing overlap and shortening the sarcomere. What is the sliding filament theory of muscle contraction, and how does it explain the shortening of the sarcomere?
The sliding filament theory states that muscle contraction occurs when myosin (thick filaments) pull on actin (thin filaments), causing them to slide past each other. This increases the overlap between myosin and actin, shortening the sarcomere without changing the length of the filaments themselves. Describe the structural components of a sarcomere and their functions.
The sarcomere's structural components include Z-discs (mark the ends and anchor actin), the M-line (anchors myosin in the center), I-bands (light bands with only actin), A-bands (dark bands with both actin and myosin), and the H-zone (center of A-band with only myosin). How do the I-band, A-band, and H-zone change during muscle contraction?
During contraction, the I-band and H-zone become narrower as actin slides over myosin, increasing their overlap. The A-band remains the same length because it corresponds to the length of the myosin filaments, which do not change.
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