What is a muscle fiber? What is a myofibril? Which main molecules comprise the thin and...

What is a muscle fiber? What is a myofibril? Which main molecules comprise the thin and thick filaments? The thin filament also has two additional proteins – what are they?

Expert Solution

Muscle fibers are formed from the fusion of developmental myoblasts in a process known as myogenesis. Muscle fibers are cylindrical and have more than one nucleus. They also have multiple mitochondria to meet energy needs. Muscle fibers are in turn composed of myofibrils.

A myofibril is a basic rod-like unit of a muscle cell. Muscles are composed of tubular cells called myocytes, known as muscle fibers in striated muscle, and these cells, in turn, contain many chains of myofibrils.

Myofibrils are composed of long proteins including actin, myosin, and titin, and other proteins that hold them together. These proteins are organized into thick and thin filaments called myofilaments, which repeat along the length of the myofibril in sections called sarcomeres. Muscles contract by sliding the thick (myosin) and thin (actin) filaments along with each other.

Each thin filament is made up of three proteins: (1) actin, (2) troponin, and (3) tropomyosin. Actin though is the main protein component of the thin filament.

gladiator answered 2 years ago

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