The eukaryotic cytoskeleton is a highly dynamic network of filaments and motor proteins. Which of the following correctly describe activities of these cytoskeletal components? Select True or False for each statement. T/F Myosin motors walk toward the plus ends of intermediate filaments. T/F Dynein motors are responsible for the whip-like movement of eukaryotic flagella. T/F Kinesin motors move vesicles along tracks toward the microtubule-organizing center. T/F Actin filaments are required for cytoplasmic streaming.

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1. False. Myosin motors walk toward the plus ends of actin filaments, not intermediate filaments.
2. True. Dynein motors are indeed responsible for the whip-like movement of eukaryotic flagella by sliding microtubules against each other.
3. False. Kinesin motors generally move vesicles toward the plus ends of microtubules, away from the microtubule-organizing center.
4. True. Actin filaments are essential for cytoplasmic streaming, which is the movement of the fluid substance (cytoplasm) within a plant or animal cell.

Key Concepts

Cytoskeletal Components

The cytoskeleton is composed of three main types of filaments: microtubules, actin filaments, and intermediate filaments. Microtubules are involved in cell shape, transport, and division; actin filaments play a crucial role in muscle contraction and cell motility; and intermediate filaments provide structural support. Understanding these components is essential for analyzing their functions and interactions within the cell.

Motor Proteins

Motor proteins, such as myosin, kinesin, and dynein, are essential for cellular movement and transport. Myosin typically interacts with actin filaments to facilitate muscle contraction and cellular movements, while kinesin and dynein transport cellular cargo along microtubules in opposite directions. Recognizing the specific roles of these motor proteins helps clarify their contributions to cytoskeletal dynamics.

Cytoplasmic Streaming

Cytoplasmic streaming is the movement of the fluid substance (cytoplasm) within a plant or animal cell, facilitated by the cytoskeleton, particularly actin filaments. This process is crucial for distributing nutrients, organelles, and signaling molecules throughout the cell. Understanding cytoplasmic streaming is important for grasping how cells maintain homeostasis and respond to environmental changes.