During interphase, the cell grows normally while concurrently preparing for cell division. It is the cell cycle's longest phase. This is the phase in which a cell spends around 90% of its time. Many internal and external parameters must be satisfied for a cell to transition from interphase to mitotic phase. If these conditions are not met, then the cell will re-enter interphase. The length of interphase varies by type of cell but ranges from 24 hours for certain types of immune cells to several days for others such as skin cells.
Cells need to replicate their DNA before dividing into two new cells with an even distribution of genetic material. However, it takes place only during mitosis when the cell is in metaphase or telophase. The other phases of the cell cycle include G1 (growth), S (DNA synthesis), and G2 (growth). Interphase can also be divided into early and late depending on how long it lasts: early interphase if it is less than 30 minutes and late interphase if it is more than 30 minutes.
Cells use various mechanisms to determine when to enter into mitosis and when to remain in interphase. Natural factors that can affect the cell's decision include age, health, and environment. For example, older cells may not be able to maintain sufficient levels of key proteins necessary to stay in interphase. This could be due to decreased gene expression, increased protein degradation, or both.
The longest phase of the cell cycle is interphase. The cell develops to its maximal size, performs its regular cellular tasks, duplicates its DNA, and prepares for cell division during this phase. Some cells no longer require division and hence quit the cell cycle. Others begin the process of division right away without a rest period.
Human skin cells divide about 100 times in their lifetime. During these 100 divisions, they go through all four stages of the cell cycle: G1, S, G2, and M. Interphase is by far the largest part of the cell cycle; it makes up 75% or more in many types of cells. Mitosis accounts for about 12% of the cell cycle and requires about as much time as interphase.
Cells need time to prepare for division (also called "growth"). The nucleus grows, proteins are made, and cell membranes are reproduced during this phase. It also provides time for genetic information to be passed on from one generation to the next. Interphase is therefore very important for growth and reproduction.
A cell that does not stop dividing will eventually die after completing several rounds of replication. Most normal human tissues contain hundreds to thousands of different types of cells; each has a unique role to play in maintaining life. Some remain in a dormant state for years before becoming activated when needed. Other cells such as stem cells are able to divide indefinitely.
This is the stage during which the cell develops and duplicates its DNA before entering mitosis. Chromosomes will align, separate, and migrate into new daughter cells during mitosis. Interphase occurs between one mitotic (M) phase and the next, as the prefix inter-means between. During this time, the cell does not divide, but grows in size and copies its DNA.
Interphase can last for a few hours or several days depending on the type of cell. Some cells may remain in interphase for many hours or even days before moving on to the next phase. Others will proceed from G1 to S phase and then to G2 before dividing. Only when ready will they enter M phase and start the process over again.
All cells go through interphase at some point in their life cycles. However most cells do not live very long past this point due to aging or damage to their DNA. These cells are referred to as "post-mitotic" because they cannot divide anymore. They will eventually die after completing another phase of the cell cycle called "apoptosis" (meaning "cell death").
Some cells such as blood cells, muscle cells, and nerve cells continue to produce proteins and hormones throughout their lifetime. These special cells, known as "progenitor cells", are able to reproduce themselves by forming new progenitors cells that contain the same genetics as themselves.
A cell spends the majority of its time in what is known as interphase, which is when it grows, copies its chromosomes, and prepares for cell division. The cell then exits interphase, goes through mitosis, and divides completely. Interphase can be divided into four distinct stages: G1, S, G2, and M.
In G1, the cell increases in size and makes proteins necessary for division. It also repairs DNA damage that may have occurred during replication or other activities such as exposure to radiation. The length of G1 varies depending on how fast the cell divides, so cells with a slow rate of growth go through a lot of G1 before dividing. For example, a cell that divides once every five days will have gone through one-quarter of its G1 period before it divides. A cell that divides twice as often will have gone through half of its G1 period before it divides. A cell that divides three times as often will have gone through two-thirds of its G1 period before it divides.
In S, the cell replicates its genome and synthesizes DNA and RNA molecules required for transcription of DNA into protein. This process requires a great deal of energy and many different types of enzymes. It also creates a large number of fragments of DNA that are not incorporated into the genome and must be removed from the nucleus for reuse by the cell or destroyed.