Question

Actin filaments are part of the contractile machinery in smooth muscle cells of eukaryotic organisms. Which organelle is responsible for contractile movement in these cells?

endoplasmic reticulum

nucleus

plasma membrane

cytoskeleton

Answer 1

The cytoskeleton is responsible for contractile movement in smooth muscle cells, primarily through the interaction of actin filaments with myosin.

Step-by-step explanation:

The organelle responsible for contractile movement in smooth muscle cells of eukaryotic organisms is the cytoskeleton. The cytoskeleton is composed of microfilaments, intermediate filaments, and microtubules. Actin filaments, which are a type of microfilament, work alongside myosin to facilitate the contraction of muscle cells. This well-studied interaction between actin and myosin is the basis of muscle contraction, including in smooth muscle cells where involuntary contractions are necessary for various body functions such as digestion and circulation. The process of muscle contraction in smooth muscle tissue does not exhibit the striations typically observed in skeletal muscle because the structure of smooth muscle is different, with actin and myosin arranged in a less orderly fashion.

Answer 2

The interaction of motor proteins such as dynein, is responsible for the movement of organelles in cells which uses energy to move parts of the cytoskeleton. Cytoskeleton is a network of intermediate filaments, microtubules and microfilaments that outspread throughout the cytoplasm and serve a variety of signaling, transport and mechanical functions.