Question

Which of the following describes the structure of an actin filament?

A. It is a hollow cylinder made up of actin molecules.
B. It is a double helix made of actin molecules.
C. It is a structure with a long tail and two globular heads.

Answer 1

The structure of an actin filament is described as a double helix made up of actin molecules, critical for cellular functions like muscle contraction and maintaining cell shape.

Step-by-step explanation:

The structure of an actin filament can be described as two thin actin chains twisted around one another, forming a double helix made up of actin molecules. Actin filaments, also known as microfilaments, are integral to the cytoskeleton of the cell and play a critical role in muscle contraction, supporting the cell's shape, and enabling cellular movement . Actin, a protein that forms chains, is the primary component of these microfilaments. The polymerization and depolymerization of actin contribute to its dynamism, allowing the microfilaments to support a variety of cellular functions including ameboid movement and muscle contraction. The interaction between actin and the motor protein myosin, especially in muscle cells, underlies the process by which muscle contraction is achieved.

Answer 2

Actin filaments are double helical structures formed by two intertwined strands of actin, critical for muscle contraction and cell movement.

Step-by-step explanation:

The structure of an actin filament is described as a double helix made of actin molecules. More specifically, microfilaments, also known as actin filaments, are composed of two intertwined strands of actin, with each strand made up of polymerized actin monomers. This twin-helical structure allows actin filaments to play a critical role in muscle contraction, cell movement, and maintaining cell shape. Actin filaments interact with the motor protein myosin to facilitate muscle contraction, while also contributing to the cellular cytoskeleton to support cell structure.