Striated muscles contain repeating sarcomeres of overlapping arrays of long, thin actin and thicker myosin filaments. Myosin filaments contains the myosin heads, which are enzymes that can bind to actin, split and make use of the energy from ATP. When muscle contraction starts, myosin heads bind to actin, change their configuration on actin, liberating the products of ATP hydrolysis and causing slide of the actin and myosin filaments. The action of the proteins troponin and tropomyosin on the actin filaments regulates vertebrae striated muscle contraction. The release of calcium ions from the sarcoplasmic reticulum is triggered by the nervous stimulation which causes depolarization of muscle membrane. Calcium ions bind to troponin and thus cause or allow the tropomyosin strands on the actin filament to move so that the part of the actin surface where myosin heads need to bind is uncovered. Contraction then occurs and only stops when the sarcoplasmic reticulum pumps calcium out of the muscle interior.
So basically, what triggers the uncovering of the myosin binding site on actin is the calcium ions binding to troponin and changing configuration.
C) The core contains equal amounts of hydrogen and helium
Answer:
The correct answer is "each of the MHC genes has a large number of alleles, but each individual only inherits two for each gene".
Explanation:
In normal conditions, an individual has only two different alleles for a given gene: one inherited from his mother and the other from his father. However, this does not mean that among humans, there are only two different alleles for each gene. The major histocompatibility (MHC) genes are a clear example of this, since there are multiple combinations for each MHC class. For instance, there are 40 very similar alleles only for the HLA-B27 subtype.
<span>I suggest dialysis to the patient. Dialysis is a medicine. People who failed with the kidneys may have difficulty eliminating waste and unwanted water from the blood. Dialysis is an artificial way of carrying out this process. Dialysis substitutes the natural work of the kidneys.</span>
