Cytochalasin B is a chemical that disrupts microfilament formation. This chemical would interfere with:
a. DNA replication
b. Formation of the mitotic spindle
c. Cleavage
d. Formation of the cell plate

Verified step by step guidance

1. Understand the role of microfilaments in the cell. Microfilaments are part of the cytoskeleton and are primarily composed of actin. They play a key role in maintaining cell shape, enabling cell movement, and facilitating processes like cytokinesis during cell division.
2. Analyze the options provided in the question. Each option represents a cellular process: DNA replication, formation of the mitotic spindle, cleavage, and formation of the cell plate. Determine which of these processes relies on microfilaments.
3. Recall that DNA replication occurs in the nucleus and is primarily dependent on enzymes like DNA polymerase, not microfilaments. Therefore, cytochalasin B would not interfere with DNA replication.
4. Consider the formation of the mitotic spindle. The mitotic spindle is composed of microtubules, not microfilaments. Cytochalasin B disrupts microfilaments, so it would not interfere with spindle formation.
5. Evaluate cleavage and formation of the cell plate. Cleavage (cytokinesis in animal cells) involves the contractile ring, which is made of actin microfilaments. Formation of the cell plate (cytokinesis in plant cells) involves vesicle fusion and is not directly dependent on microfilaments. Therefore, cytochalasin B would interfere with cleavage.

Key Concepts

Microfilaments

Microfilaments are thin, thread-like structures made of actin that are part of the cytoskeleton in eukaryotic cells. They play crucial roles in maintaining cell shape, enabling cell movement, and facilitating cell division. Disruption of microfilament formation can significantly affect cellular processes, particularly those involving changes in cell shape and motility.

Cytokinesis

Cytokinesis is the process during cell division where the cytoplasm of a parental cell is divided into two daughter cells. In animal cells, this involves the formation of a cleavage furrow, which is driven by the contraction of microfilaments. Disruption of microfilament formation by Cytochalasin B would hinder this process, preventing proper cell division.

Cell Plate Formation

In plant cells, cell plate formation is a critical step during cytokinesis, where vesicles containing cell wall materials fuse at the center of the dividing cell to form a new cell wall. This process is also dependent on the cytoskeleton, including microfilaments, to guide the vesicles to the correct location. Disruption of microfilament formation would impair the ability to form a cell plate, affecting plant cell division.