<span>There are numerous proteins in muscle. The main two are thin actin filaments and thick myosin filaments. Thin filaments form a scaffold that thick filaments crawl up. There are many regulatory proteins such as troponin I, troponin C, and tropomyosin. There are also proteins that stabilize the cells and anchor the filaments to other cellular structures. A prime example of this is dystrophin. This protein is thought to stabilize the cell membrane during contraction and prevent it from breaking. Those who lack completely lack dystrophin have a disorder known as Duchene muscular dystrophy. This disease is characterized by muscle wasting begininng in at a young age and usually results in death by the mid 20s. The sarcomere is the repeating unit of skeletal muscle.
Muscle cells contract by interactions of myosin heads on thick filament with actin monomers on thin filament. The myosin heads bind tightly to actin monomers until ATP binds to the myosin. This causes the release of the myosin head, which subsequently swings foward and associates with an actin monomer further up the thin filament. Hydrolysis and of ATP and the release of ADP and a phosphate allows the mysosin head to pull the thick filament up the thin filament. There are roughly 500 myosin heads on each thick filament and when they repeatedly move up the thin filament, the muscle contracts. There are many regulatory proteins of this contraction. For example, troponin I, troponin C, and tropomyosin form a regulatory switch that blocks myosin heads from binding to actin monomers until a nerve impulse stimulates an influx of calcium. This causes the switch to allow the myosin to bind to the actin and allows the muscle to contract. </span><span>
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Explanation:
A university is building a new student center that is one third the distance from the arts center to the Academic.
Answer:
Explanation:
friction between two rock surfaces grinding away minerals.
An example of a missense mutation in a protein-encoding gene would most likely be a neutral mutation is option B: replacement of a polar amino acid with another polar amino acid at the protein's surface.
A frequent and well-known example of a missense mutation is the blood condition sickle-cell anemia. Missense mutations exist in the DNA at a single location in sickle-cell anemia patients. A different amino acid is required in this missense mutation, which also alters the overall structure of the protein. Similarly, replacement of a polar amino acid by another polar Ami no acid at the protein's surface is a missense mutation causing change in a single site.
A neutral mutation is one whose fixation is unrelated to natural selection. Therefore, the independence of a mutation's fixation from natural selection can be used to define the selective neutrality of a mutation.
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Complete question is:
Which example of a missense mutation in a protein-encoding gene would most likely be a neutral mutation?
a) Replacement of a polar amino acid with a nonpolar amino acid at the protein's outer surface
b) Replacement of a polar amino acid with another polar amino acid at the protein's surface
c) Replacement of a polar amino acid with another polar amino acid in the protein's interior
d) Replacement of a polar amino acid with a nonpolar amino acid in the protein's interior
