BRAINCAKEMyofibrils
Myofibrils are long, cylindrical rod-like organelles found in muscle fibres. They are made of proteins actin and myosin and are the contractile elements of the muscle fibre. They are lined up so that when they all contract together they provide the maximum force possible.
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Key terms in this lesson
- sarcomere
- The contractile unit of a myofibril, delineated by two Z-lines, containing overlapping actin and myosin filaments.
- actin
- A thin protein myofilament in a myofibril that, together with myosin, slides during muscle contraction; its myosin-binding sites are covered by tropomyosin in resting muscle.
- myosin
- A thick protein myofilament with a hinged globular head that binds to actin and ATP and pulls actin filaments during muscle contraction.