Guided Study: Cytoskeletal Elements, Motor Proteins, and Membrane Receptors

Q1. Match the terms (microtubules, microfilaments, motor proteins, receptors on cell membrane) with the appropriate statements (A–W).

Background

Topic: Cell Structure and Function – Cytoskeleton and Membrane Proteins

This question tests your understanding of the structure, function, and characteristics of key cellular components: microtubules, microfilaments, motor proteins, and membrane receptors. You are asked to match each term with the statements that best describe them.

Key Terms and Concepts:

• Microtubules: Cylindrical polymers of tubulin, largest cytoskeletal filaments, involved in cell shape, transport, and division.

• Microfilaments: Also called actin filaments, double helices of actin, involved in cell movement and structure.

• Motor Proteins: Proteins (like kinesin, dynein, myosin) that move along cytoskeletal filaments using ATP.

• Receptors on Cell Membrane: Integral membrane proteins that receive and transmit signals or facilitate transport.

Key Features and Functions:

• Microtubules:

  • Largest cytoskeletal elements

  • Dynamic instability (grow/shrink at ends)

  • Organized from MTOCs (e.g., centrosomes)

  • Involved in mitotic spindle, cilia, flagella

  • Work with motor proteins (kinesin, dynein)

• Microfilaments:

  • Double helices of actin

  • Support microvilli, contractile ring in cytokinesis

  • Involved in muscle contraction (with myosin)

• Motor Proteins:

  • Use ATP to move along filaments

  • Examples: kinesin, dynein (microtubules), myosin (actin)

• Receptors on Cell Membrane:

  • Integral membrane proteins

  • Receive extracellular signals

  • Often synthesized in ER, transported via vesicles

Step-by-Step Guidance

1. Read each statement (A–W) carefully and identify the key words or phrases that indicate which cellular component is being described. For example, statements mentioning 'largest diameter' or 'dynamic instability' are likely about microtubules.

2. Recall the main features of each term. For instance, microfilaments are made of actin, so statements about 'double helices of actin' or 'contractile ring' relate to microfilaments.

3. For motor proteins, look for statements about movement, ATP usage, or interactions with cytoskeletal elements (e.g., 'work with kinesin', 'muscle contraction').

4. For receptors on the cell membrane, focus on statements about being integral membrane proteins, signal reception, or synthesis in the ER and vesicular transport.

5. Match each term with all the statements that fit its characteristics. Some statements may apply to more than one term, so consider overlaps carefully.

Try solving on your own before revealing the answer!

Final Answer:

• Microtubules: A, C, D, E, H, I, J, K, L, O, R, S, T, V

• Microfilaments: B, C, E, G, H, J, I, M, N, T

• Motor Proteins: D, E, G, H, I, N, U, W

• Receptors on Cell Membrane: E, F, H, P, Q

Each term is matched with the statements that best describe its structure, function, or synthesis. Review the definitions and functions to understand why each statement fits.