Final answer:
Extracellular signals that alter the arrangement of actin filaments include growth factors, cytokines, integrin-mediated signals, and apoptotic signals. Specifically, growth factors, cytokines, and integrin-mediated signals cause actin filaments to reorganize and facilitate various cellular activities such as movement, growth, and division. Apoptotic signals induce changes in the cytoskeleton associated with cell death.
Step-by-step explanation:
The subject in question pertains to the alterations in the arrangement of actin filaments within cells, which are influenced by extracellular signals. These signals can lead to various cellular responses such as changes in protein expression, cellular metabolism, and cell division. Examples of extracellular signals that can alter the arrangement of actin filaments include:
- Growth factors: These are one of the primary signals that trigger cell division and growth. When growth factors bind to their receptors on the cell surface, they initiate a cascade of intracellular events that can change the conformation and dynamics of actin filaments, leading to cellular responses such as movement, growth, and division.
- Cytokines: These signaling molecules are involved in the immune response and can influence the cytoskeleton, thus affecting actin filament arrangement.
- Integrin-mediated signals: Integrins are transmembrane receptors that bind the extracellular matrix (ECM) to the actin cytoskeleton, facilitating cell adhesion and signaling events that can lead to the reorganization of actin filaments.
- Apoptotic signals: While these signals lead a cell towards programmed cell death, they too can influence the actin cytoskeleton as the cell undergoes morphological changes during apoptosis.
It should be noted that although apoptotic signals do affect the cytoskeleton, they are primarily associated with the breakdown of the cell, rather than reorganization for cellular activities such as movement or division, which is more characteristic of the impact from growth factors, cytokines, and integrin-mediated signals.