Myofibril structure
The structure of the myofibril
The myofibrils contain the contractile apparatus of the muscle. These are called myofilaments and are divided into thick and thin filaments.
The thick filament is mainly composed of hundreds of myosin molecules. The thin filament consists of two chains of actin molecules helically intertwined. Also present on the thin filament are the regulatory proteins troponin and tropomyosin.
The myofibril has a very regulated structure with alternating light and dark bands. The repeating unit of the myofibril is known as the sarcomere.
Challenge Quiz
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<GIFT> //LEVEL:2 //RAND The contractile apparatus of the muscle are {~=Myofilaments~myofibrils}.
//LEVEL:2 //RAND The thick filament consists mainly of {~actin~=myosin}.
//LEVEL:2 //RAND The thin filament consists mainly of {~=actin~myosin}.
//LEVEL:2
//RAND
The repeating unit of the myofibril is the {~=sarcomere~tropomyosin~actin}.
//LEVEL:2 //RAND Which one of the following is not part of the structure of the thin filament {~=actin~=myosin~troponin~tropomyosin}