Muscle Fiber Case Study

The muscle fibers in the presence of ATP contracted 0.07cm and 3.3% change. Under the microscope, figure 1 shows the striated fiber by clearly indicating the bands and lines of the striation. In addition, solution B, with ATP plus Salt (KCl, MgCl2) contracted the muscle fiber by 0.24cm and 9.2% change. Finally, solution C, containing only salt (KCl, MgCl2) also contracted the muscle fiber by 0.13cm and 6.1% change. Figure 2 shows the effect after adding salt and shows the striations of the fiber. Therefore, muscle fibers were found to contract after the application of the three solutions. However, solution B (ATP + Salt), had a greater effect than the other two solutions based on the percentage of contraction which was 9.2%.
Discussion:
Petri Dish A
The muscle fibers in the presence of ATP shortened by 0.07cm and 3.3% change, which means that the muscle contracted. According to Boundless, ATP is required for muscle contraction since it prepares the myosin for binding in the cross-bridge muscle contraction cycle (Boundless). Thus, ATP activates the myosin heads for binding to actin forming a cross-bridge and then the myosin head bends, which release ADP and phosphate. At the molecular level, Fox explains that the muscle filaments are composed of actin monomers in a …show more content…
The fibers might have contracted due to the myosin’s affinity for the KCl and MgCl2 ions, but in this case, there wasn’t ATP present, and if there is no ATP, the myosin heads in the muscle will no be activated and thus, it will not bind to actin to cause a contraction. Therefore, the results rejects the hypothesis made, because only salt made the muscle fibers contract and instead, it should have caused an elongation in the muscle fibers since magnesium is known to make the muscles relax. Additionally, the muscle could not possibly contract without the activation of the myosin heads by