2.2UltrastructureofMuscle fibre(EM)2.2.1 Myofibril: made up of thick filament (myosin filament)and thin filament (actin filament )tick filament: made up of myosin moleculesmyosin: bean sprout in shape, having 2 heads and 1 tailThe head has an ATP-binding site and an actinbinding site.It is an inactive ATPase
2.2.1 Myofibril: made up of thick filament (myosin filament) and thin filament (actin filament ). thick filament: made up of myosin molecules myosin: bean sprout in shape, having 2 heads and 1 tail. The head has an ATP-binding site and an actinbinding site.It is an inactive ATPase. 2.2 Ultrastructure of Muscle fibre ( EM )
thickfilamentone myosinmyosin headsmolecule(cross bridges)myosintails
thick filament
+ thin filament: made up of actin, tropomyosinand troponin.actin: its monomer appears spheral, eachmonomer has a myosin binding siteMonomers polymerise each other to forma long double helix chaintropomyosin: two helical polypeptide- chainslocalized in the grooves of the actintroponin : attached to the surface of tropomyosin.able to combine with Ca2+
thin filament: made up of actin, tropomyosin and troponin. actin: its monomer appears spheral，each monomer has a myosin binding site. Monomers polymerise each other to form a long double helix chain. tropomyosin: two helical polypeptide- chains. localized in the grooves of the actin. troponin：attached to the surface of tropomyosin. able to combine with Ca2+