many organelles and molecules needed for cell division are formed after DNA replication and before mitosis.In which phase are they formed??

G2

The organelles and molecules needed for cell division are formed during the interphase of the cell cycle. Interphase consists of three stages: G1 (gap 1), S (synthesis), and G2 (gap 2). DNA replication occurs during the S phase, where each chromosome is duplicated. After DNA replication, the cell enters the G2 phase, during which the organelles and molecules required for cell division are formed. Finally, mitosis occurs in the M phase, where the cell divides into two daughter cells.

The organelles and molecules required for cell division, such as centrioles, spindle fibers, and cell membrane components, are formed during a specific phase of the cell cycle known as the Gap 2 phase (G2 phase).

To understand this, let's first review the cell cycle. The cell cycle consists of several stages: interphase, which includes G1 phase, S phase, and G2 phase, and mitosis (which is further divided into prophase, metaphase, anaphase, and telophase).

During interphase, the DNA is replicated in the S phase, which ensures that each daughter cell will have a complete set of chromosomes. After DNA replication, the cell enters G2 phase, which is a period of growth and preparation for cell division.

During G2 phase, the cell synthesizes the proteins, organelles, and molecules necessary for mitosis. For example, the centrioles, which play a crucial role in organizing the spindle fibers, are duplicated during this phase. The spindle fibers themselves, which help separate the chromosomes during mitosis, also begin to form. Additionally, the cell synthesizes components for the cell membrane, which will be needed for cytokinesis (the division of the cytoplasm at the end of cell division).

Therefore, to answer your question, the organelles and molecules required for cell division are formed during the G2 phase of the cell cycle.