Myofibril: Difference between revisions
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The myofibril is a long contractile unit made of the myofilaments [[Actin|actin]] and [[Myosin|myosin ]] | The myofibril is a long contractile unit made of the myofilaments [[Actin|actin]] and [[Myosin|myosin which]] form the [[Sarcomere|sarcomere]]. They line up parallel to one another forming cylindrical structures which bundle together into a muscle fibre. The regular arrangement of cross striations of sarcomeres, which can be observed under a low magnification [[Electron Microscopy|electron microscope]], attribute to the alternative name given to skeletal muscles: striated muscle. An electron micrograph of myofibrils shows differently shaded bands. These are representitive of the different density protein filaments: | ||
<br>- Z discs: thick, darkly stained, short filaments which mark the start and end of the sarcomere.<br>- A bands: thick, darkly stained region which marks the locations of myosin filaments. <br>- M lines (or midlines) : thin, darkly stained, short vertical filaments which link the two myosin II complexes of the sarcomere at their tail regions.<br> - I bands : thin, lightly stained region which marks the locations of actin filaments. | <br>- Z discs: thick, darkly stained, short filaments which mark the start and end of the sarcomere.<br>- A bands: thick, darkly stained region which marks the locations of myosin filaments. <br>- M lines (or midlines) : thin, darkly stained, short vertical filaments which link the two myosin II complexes of the sarcomere at their tail regions.<br> - I bands : thin, lightly stained region which marks the locations of actin filaments.<ref name="Molecular Biology of The Cell">Alberts B, Johnson A, Lewis J, Raff M, Roberts K and Walter P. (2008) Molecular Biology of The Cell, 5th edition, New York: Garland Science</ref> | ||
<ref name="Molecular Biology of The Cell">Alberts B, Johnson A, Lewis J, Raff M, Roberts K and Walter P. (2008) Molecular Biology of The Cell, 5th edition, New York: Garland Science</ref> | |||
Revision as of 17:21, 29 November 2011
The myofibril is a long contractile unit made of the myofilaments actin and myosin which form the sarcomere. They line up parallel to one another forming cylindrical structures which bundle together into a muscle fibre. The regular arrangement of cross striations of sarcomeres, which can be observed under a low magnification electron microscope, attribute to the alternative name given to skeletal muscles: striated muscle. An electron micrograph of myofibrils shows differently shaded bands. These are representitive of the different density protein filaments:
- Z discs: thick, darkly stained, short filaments which mark the start and end of the sarcomere.
- A bands: thick, darkly stained region which marks the locations of myosin filaments.
- M lines (or midlines) : thin, darkly stained, short vertical filaments which link the two myosin II complexes of the sarcomere at their tail regions.
- I bands : thin, lightly stained region which marks the locations of actin filaments.[1]
- ↑ Alberts B, Johnson A, Lewis J, Raff M, Roberts K and Walter P. (2008) Molecular Biology of The Cell, 5th edition, New York: Garland Science