four question analysis on "The myosin-interacting protein SMYD1 is essential for sarcomere organization" by Just et al. (2011) 1.) Wild-type Fla Mutant (SMYD-deficient) In the current study, the authors used a zebra fish mutant known as Flatline (fla). This mutant contains a nonsense mutation within the SMYD1 gene, consequently, these mutants show disturbed sarcomere assembly. The authors observed that fla mutants had properly assembled hearts with healthy myo- and endocardial cell layers but their cardiac tissue showed no contraction under stimulation. They also concluded that the cardiac electrical impulse was the same for both wild-type and…
They have higher levels of PPARβ/δ to increase fatigue resistance and act as a transcription factor to promote ‘slow’ genes. Slow twitch muscle fibers also have slow Calcium ATPase and lower activity myosin ATPase, which both work to cause longer contractions. Fast twitch, type II, fibers are the opposite of slow twitch fibers and involve more anaerobic activity. They have fast Calcium ATPase and High activity Myosin ATPase causing shorter, faster contractions. These muscles have three types;…
The SR is extensive and covering all the myofibrils this allows fine control of contractions of the myofibrils due to depolarization only affecting the targeted areas since the SR release of calcium ions is the key to muscle contraction. Myofibrils are protein bundles containing actin and myosin. Actin (thin) and myosin (thick) make up a unit of skeletal muscle cell called a sarcomere, the main unit of contraction in skeletal muscle cells. The patterns of sarcomeres make up the striations or the…
Once the bridges are formed, the myosin pulls on the actin contracting the muscle. Cross bridge formation can only occur, however, when the binding sites on the actin are free. Calcium ions work to free up the myosin binding sites on actin. When a muscle is relaxed, a protein called tropomyosin blocks the myosin binding site. Calcium rushes into the cell and attaches to a special protein troponin when a muscle is stimulated by a nerve cell. The troponin then changes shapes and pulls the…
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…
shortening the sarcomere. These two filaments do the real job of a muscle. Thick filaments are comprised by a protein called myosin, which has significant assets of resistance and contractibility. These myosin protein molecules are shaped like a pair of hockey sticks twisted together. On the other hand, thin filaments are made up by a protein called actin. Molecules of actin connected to one another form chains twisted into a helix structure. Actin plays a crucial role for the mechanism in…
However, there are only a limited motor unit and nerve fibers in a given organism therefore, there will be point at which all the units and fibers will be saturated and the intensity of stimulation. A single AP can cause a twitch in a muscle. The latent time in this experiment was 33 ms. This signifies the time it takes for the stimulus to depolarize the t-tubule, send an AP towards the muscle fiber, activate the Ca++ channels, and to allow actin myosin to join and start a contraction. The rate…
As mentioned previously, the amount of force produced by a muscle is linked directly to the number of actin and myosin fibers in a muscle. This explains why the larger muscles which contain a greater number of actin and myosin, produce a greater force. Resistance training can cause the muscle size to grow in two ways, hypertrophy or hyperplasia (Powers, 2015). Hyperplasia is an increase in the total number of muscle fibers in a single muscle. However, there is not much evidence that muscle…
to Ra, lowering the length constant. 4. Adenosine triphosphate (ATP) plays an important role in a striated muscle twitch, especially in the cross-bridge cycling. In a relaxed state, ATP is partially hydrolyzed at the binding site in myosin, keeping myosin in a high-energy state. When there’s an elevated Ca++ inside a muscle cell, high-energy state myosin binds to actin, forming the cross-bridge. Upon cross-bridge formation, ATP is hydrolyzed, which causes a conformational change in the myosin…
would be used to describe a large artery or vein (Hill et. al 2016). Like skeletal muscles, smooth muscles use the contractile proteins actin (thin filament) and myosin (thick filament); however, these proteins are not arranged into sarcomeres, so the cells do not appear striated. These thin and thick filaments interact with each other in the presence of calcium (Ca²⁺) in order to form cross bridges. The cross bridges allow for these filaments to slide by one another, thereby undergoing the…