Multiple Choice
According to the sliding filament model, binding sites on actin open when which of the following occurs?
122
views
9. Muscle Tissue
Sliding Filament Theory and the Sarcomere
Multiple Choice
In the context of sliding filament theory and the sarcomere, what causes the striated appearance of skeletal muscle fibers under the microscope?
A
The alternating arrangement of dark A bands and light I bands created by the overlap pattern of thick (myosin) and thin (actin) filaments within repeating sarcomeres
B
The spiral arrangement of collagen fibers in the endomysium surrounding each muscle fiber
C
The presence of intercalated discs that electrically connect adjacent skeletal muscle fibers
D
Randomly oriented actin and myosin filaments throughout the cytoplasm, producing an uneven light-scattering pattern
Verified step by step guidance1
Understand that the striated appearance of skeletal muscle fibers is due to the microscopic arrangement of protein filaments within the muscle cells, specifically within the sarcomeres, which are the basic contractile units.
Recall that sarcomeres contain thick filaments made of myosin and thin filaments made of actin, which are organized in a highly ordered, repeating pattern along the length of the muscle fiber.
Recognize that the dark A bands correspond to regions where thick myosin filaments overlap with thin actin filaments, creating a denser, darker appearance under the microscope.
Identify that the light I bands correspond to regions containing only thin actin filaments without overlapping thick filaments, resulting in a lighter appearance.
Conclude that the alternating pattern of dark A bands and light I bands along the sarcomere length produces the characteristic striated pattern observed in skeletal muscle fibers.
Related Videos
Related Practice
