Question

match the description with the correct component of a muscle fiber.
a table shows the structure and description of components in the structure. the data in the second column is listed in the dropdown fields.

Explanation:

• Site for storage of calcium: The sarcoplasmic reticulum is a specialized organelle in muscle cells that stores calcium ions (\(Ca^{2+}\)). When a muscle is stimulated to contract, calcium is released from the sarcoplasmic reticulum into the cytoplasm.
• Threadlike bundles of thick and thin filaments: Myofibrils are composed of thick (myosin) and thin (actin) filaments. These filaments interact during muscle contraction through a process called the sliding - filament mechanism.
• Channel formed by invagination of plasma membrane: Transverse (T) tubules are invaginations of the plasma membrane (sarcolemma) into the muscle fiber. They help in the rapid transmission of the action potential from the surface of the muscle fiber to its interior.
• Plasma membrane of muscle fiber: The sarcolemma is the plasma membrane of the muscle fiber. It is involved in the generation and propagation of action potentials, which are crucial for muscle contraction.
• Cytoplasm of muscle fiber: The sarcoplasm is the cytoplasm of the muscle fiber. It contains various organelles, including mitochondria (for ATP production) and myofibrils.
• Site of ATP production: Mitochondria are the powerhouses of the cell. In muscle fibers, they produce ATP through cellular respiration (aerobic or anaerobic, depending on the muscle type and activity level), which is used for muscle contraction.
• Functional unit of contraction within muscle fiber: The sarcomere is the basic functional unit of muscle contraction. It is the region between two successive Z - lines and contains the overlapping thick and thin filaments.

Answer:

Description	Structure
Threadlike bundles of thick and thin filaments	Myofibril
Channel formed by invagination of plasma membrane	Transverse (T) tubule
Plasma membrane of muscle fiber	Sarcolemma
Cytoplasm of muscle fiber	Sarcoplasm
Site of ATP production	Mitochondria
Functional unit of contraction within muscle fiber	Sarcomere