Question

What are the different levels of organization of a muscle down to myofilaments? What is a "sarcomere" and how are its proteins organized?

Answer 1

Answer:

Muscle fiber → myofibrils → myofilaments → sarcomere.

The muscles are made up of long cylindrical muscle cells called muscle fibres which are organized together in bundles to form muscle bundles.  The muscle fibres are formed by the fusion of the myoblasts which consists of nucleus and mitochondria to provide energy.

The muscle fibres are composed of the myofibrils which contain the myofilaments mainly the thin filaments called actin and the thick filaments called myosin.

These actin and myosin are arranged in repeated functional units called sarcomere. The sarcomere is the basic structural and functional unit of life which helps in muscle contractions. The filaments in the muscle are arranged into bands- Isotropic and anisotropic bands.