Question

In order for cell division to occur, what has to happen to DNA? (there are two major things)Why? How do both processes work?

Answer 1

Before a cell divides, the strands of DNA in the nucleus must be copied, checked for errors, this is necessary so that each of the two cells produced will have the correct number of chromosomes. The cell division stages encompass a complicated process that involves many changes inside the cell. Many proteins unwind DNA in order to copy it, which makes it vulnerable to breakage. During cell division, DNA is pulled to and fro, which can cause it to break if it is not carefully packaged.

The cell cycle is divided into two major phases: interphase and mitosis

Interphase

Interphase is the longest part of the cell cycle. This is when the cell grows and copies its DNA before moving into mitosis. During mitosis, chromosomes will align, separate, and move into new daughter cells.

Before a cell can enter the active phases of mitosis, however, it must go through a period known as interphase, during which it grows and produces the various proteins necessary for division. Then, at a critical point during interphase (called the S phase), the cell duplicates its chromosomes and ensures its systems are ready for cell division. If all conditions are ideal, the cell is now ready to move into the first phase of mitosis.

Interphase consists of three steps:

• G_11​start subscript, 1, end subscript phase: first gap phase; the cell grows larger and organelles are copied
• S phase: synthesis phase; the cell synthesizes a complete copy of the DNA in its nucleus
• G_22​start subscript, 2, end subscript phase: second gap phase; the cell grows more, makes proteins and organelles, and begins to reorganize its contents in preparation for mitosis

Cells that are meant to divide will complete G_22​start subscript, 2, end subscript and enter mitosis. Other types of cells that divide slowly or not at all may exit the G_11​start subscript, 1, end subscript phase and enter a non-dividing state called G_00​start subscript, 0, end subscript. Some cells remain here indefinitely, while others may re-enter division under the right conditions.

Mitosis (the M phase)

The process of mitosis, or cell division, is also known as the M phase. This is where the cell divides its previously-copied DNA and cytoplasm to make two new, identical daughter cells.

Mitosis consists of four basic phases: prophase, metaphase, anaphase, and telophase. Mitosis ensures that each successive cellular generation has the same genetic composition as the previous generation, as well as an identical chromosome set.