Contractile ring

Definition

The contractile ring is a structure formed during cytokinesis, which is the final stage of cell division, where the cytoplasm of a parental cell is divided into two daughter cells. It consists primarily of actin microfilaments and myosin motor proteins that work together to constrict the cell membrane, ultimately leading to the physical separation of the two cells. The contractile ring plays a crucial role in ensuring that each daughter cell receives an appropriate amount of cytoplasm and organelles, allowing for proper cell function.

5 Must Know Facts For Your Next Test

1. The contractile ring forms at the cleavage furrow during cytokinesis, which is the indentation that appears on the surface of a dividing cell.
2. Actin microfilaments in the contractile ring are organized in a ring-like structure that contracts to pinch the cell membrane inward.
3. Myosin II plays a vital role in the contractile process by generating force through interactions with actin filaments.
4. The successful function of the contractile ring is crucial for maintaining genomic stability by ensuring proper distribution of organelles and genetic material to daughter cells.
5. Disruptions in contractile ring formation can lead to errors in cytokinesis, resulting in multinucleated cells or aneuploidy, which can contribute to various diseases.

Review Questions

• How do actin microfilaments and myosin interact to facilitate the process of cytokinesis?
  • Actin microfilaments provide structural support and form the backbone of the contractile ring during cytokinesis. Myosin interacts with these actin filaments to generate force through its motor activity, effectively pulling on the filaments. This contraction pulls the plasma membrane inward, creating a cleavage furrow that deepens until it pinches the cell into two separate daughter cells.
• What happens if there is a malfunction in the contractile ring during cytokinesis, and what are the potential consequences for the daughter cells?
  • If there is a malfunction in the contractile ring during cytokinesis, it can lead to incomplete cell division, resulting in multinucleated cells or aneuploidy, where daughter cells have an abnormal number of chromosomes. This can disrupt normal cellular function and contribute to conditions such as cancer, where improper cell division is a common characteristic. Ensuring proper assembly and function of the contractile ring is therefore critical for maintaining genomic stability.
• Evaluate the importance of the contractile ring in relation to other cytoskeletal components during cell division and how it integrates with overall cellular function.
  • The contractile ring is essential for successful cytokinesis and relies on interactions between actin microfilaments and myosin motor proteins. This integration showcases how different cytoskeletal components work together; while microtubules are involved in chromosome separation during mitosis, microfilaments are critical for dividing the cytoplasm. The coordination between these components ensures that each daughter cell receives not only its share of genetic material but also necessary organelles and cytoplasmic components, which is vital for proper cellular function and homeostasis.

Related terms

cytokinesis: The process of cytoplasmic division that follows mitosis or meiosis, resulting in two daughter cells.

actin microfilaments: Thin filaments composed of actin protein that are part of the cytoskeleton, playing key roles in cell shape, motility, and division.

myosin:

A type of motor protein that interacts with actin filaments to produce contractile forces in muscle cells and other types of cells.