Question

Actin and myosin proteins are related with
A. $Na^+$ and $K^+$ pump
B. Muscle contraction
C. Nervous system
D. Excretion of water products

Answer 1

Hint: Actin is a group of globular proteins that in most eukaryotic cells are the most abundant proteins and help to provide the body with shape , structure, and mobility. Myosin is a motor protein superfamily that forms the basis for the contraction of muscle fibres along with actin proteins.

Complete Answer:
- Actin proteins are present in both the sarcomere bands A and I. Myosin proteins are only present in the A sarcomere bands. Actin proteins are proteins that are globular. The proteins in myosin are motor proteins.
- Actin filaments are made up of the proteins actin, tropomyosin, and troponin. Myosin filaments are made up of proteins from myosin and meromyosin. Actin is located in the fibres of the muscle, microfilaments, cell membrane, and cell wall.
- Myosin is primarily discovered in muscle cells. Actin interacts with myosin to facilitate muscular contraction. By producing a force by binding to the ATP molecule, myosin initiates muscle contraction.
- In order to form a thin filament, two long strands of bead-like actin molecules, bundles of which alternate and interdigitate with bundles of thick filaments produced by myosin, the most abundant protein found in muscle, twist together in the muscle.
- Actin and myosin are triggered when a signal for muscle contraction is transmitted through a nerve to a muscle cell. Myosin acts to release energy in such a way that a myosin filament travels along an actin filament, allowing the two filaments to slip past each other, as a motor, hydrolyzing adenosine triphosphate (ATP).
- The temporary fusion of actin and myosin that results in muscle contraction is regulated by two other muscle proteins, tropomyosin and troponin.

The correct answer is option (B) Muscle Contraction.

Note: Actin filaments are responsible for many types of cell movements, usually in association with myosin.