Understanding Stages of the Cell Cycle - Biology

DNA is synthesized in the S phase only. The G phases are stages of cellular growth while the M phase consists of mitotic cellular division.

During anaphase, chromosomes are split and sister chromatids move to opposite ends of the cell. This separation is caused by the shortening of a pair of spindle fibers attached to the kinetochore of each sister chromatid. The other end of the spindle fibers is attached to a centriole at each respective end of the cell, which pulls the sister chromatids apart as it shortens the fiber.

It is during prophase that DNA condenses from chromatin into chromosomes, and it is during telophase that DNA unwinds from chromosomes back into chromatin. So for every stage between these two DNA is in chromosome form. The only stages between prophase and telophase are metaphase and anaphase. In all other stages DNA is in chromatin form.

The S phase (or synthesis phase) is a period of the cell cycle during which DNA is replicated (or synthesized). G1 and G2 are both growth phases, during which cellular organelles are replicated and the cell grows in size. The M phase refers to mitosis, or cell division.

During the S phase, the cell dedicates its time to replicating its DNA. The S phase is named for the synthesis of DNA.

The G phases are needed for increasing proteins and cellular organelles, and are known for cellular growth. The M phase is also known as mitosis.

There are two stages in the cell cycle marked by the replication of organelles and protein synthesis: G1 and G2. G1 follows mitosis and allows the cell to grow. G2 occurs just before mitosis, and ensures that both daughter cells will have adequate organelles. It also allows proteins necessary for mitosis to be translated.

The overall order of the cell cycle is: G1, S, G2, M. G1 is a growth period. S marks the replication of DNA, resulting in the production of identical sister chromatids. G2 is responsible for organelle synthesis. The M phase is mitosis, or cell division.

The cell cycle consists of four major phases: G1, S, G2, and M.

The G1 phase stands for gap 1 and is when organelles replicate and the cell grows.

The S phase stands for synthesis and is when DNA is replicated.

The G2 phase stands for gap 2 and is when DNA is proofread and DNA damage is repaired.

The M phase is mitosis, which is further broken down into prophase, metaphase, anaphase, telophase, and cytokinesis. Prophase is when the chromosomes condense. Metaphase is when the chromosomes line up at the metaphase plate in the center of the cell. Anaphase is when the sister chromatids are pulled to opposite sides of the cell. Telophase is when the cell begins to split and the nuclear membrane reassembles. Cytokinesis is when the cytoplasm pinches off and two daughter cells are formed.

G0 is a separate phase, in which the cell cycle is stopped. Cells in the G0 phase are known as quiescent cells, and do not divide.

The cell cycle consists of four major phases: G1, S, G2, and M.

The G1 phase stands for gap 1 and is when organelles replicate and the cell grows.

The S phase stands for synthesis and is when DNA is replicated.

The G2 phase stands for gap 2 and is when DNA is proofread and DNA damage is repaired.

The M phase is mitosis, which is further broken down into prophase, metaphase, anaphase, telophase, and cytokinesis. Prophase is when the chromosomes condense. Metaphase is when the chromosomes line up at the metaphase plate in the center of the cell. Anaphase is when the sister chromatids are pulled to opposite sides of the cell. Telophase is when the cell begins to split and the nuclear membrane reassembles. Cytokinesis is when the cytoplasm pinches off and two daughter cells are formed.

G0 is a separate phase, in which the cell cycle is stopped. Cells in the G0 phase are known as quiescent cells, and do not divide.

The cell cycle consists of four major phases: G1, S, G2, and M.

The G1 phase stands for gap 1 and is when organelles replicate and the cell grows.

The S phase stands for synthesis and is when DNA is replicated.

The G2 phase stands for gap 2 and is when DNA is proofread and DNA damage is repaired.

The M phase is mitosis, which is further broken down into prophase, metaphase, anaphase, telophase, and cytokinesis. Prophase is when the chromosomes condense. Metaphase is when the chromosomes line up at the metaphase plate in the center of the cell. Anaphase is when the sister chromatids are pulled to opposite sides of the cell. Telophase is when the cell begins to split and the nuclear membrane reassembles. Cytokinesis is when the cytoplasm pinches off and two daughter cells are formed.

G0 is a separate phase, in which the cell cycle is stopped. Cells in the G0 phase are known as quiescent cells, and do not divide.

The cell cycle consists of four major phases: G1, S, G2, and M.

The G1 phase stands for gap 1 and is when organelles replicate and the cell grows.

The S phase stands for synthesis and is when DNA is replicated.

The G2 phase stands for gap 2 and is when DNA is proofread and DNA damage is repaired.

The M phase is mitosis, which is further broken down into prophase, metaphase, anaphase, telophase, and cytokinesis. Prophase is when the chromosomes condense. Metaphase is when the chromosomes line up at the metaphase plate in the center of the cell. Anaphase is when the sister chromatids are pulled to opposite sides of the cell. Telophase is when the cell begins to split and the nuclear membrane reassembles. Cytokinesis is when the cytoplasm pinches off and two daughter cells are formed.

G0 is a separate phase, in which the cell cycle is stopped. Cells in the G0 phase are known as quiescent cells, and do not divide.

The cell cycle consists of four major phases: G1, S, G2, and M.

The M phase is mitosis, which is further broken down into prophase, metaphase, anaphase, telophase, and cytokinesis.

Prophase is when the nuclear envelope dissolves and chromosomes condense. Metaphase is when the chromosomes line up at the metaphase plate in the center of the cell. Anaphase is when the sister chromatids are pulled to opposite sides of the cell by spindle fibers. Telophase is when the cell begins to split and the nuclear membrane reassembles. Cytokinesis is when the cytoplasm pinches off and two daughter cells are formed.

The S phase of the cell cycle is the period during which DNA is replicated.

The cell cycle consists of four major phases: G1, S, G2, and M.

The M phase is mitosis, which is further broken down into prophase, metaphase, anaphase, telophase, and cytokinesis.

Prophase is when the nuclear envelope dissolves and chromosomes condense. Metaphase is when the chromosomes line up at the metaphase plate in the center of the cell. Anaphase is when the sister chromatids are pulled to opposite sides of the cell by spindle fibers. Telophase is when the cell begins to split and the nuclear membrane reassembles. Cytokinesis is when the cytoplasm pinches off and two daughter cells are formed.

It is important to note that the cell generates two daughter nuclei during telophase, but the cytoplasm does not divide until cytokinesis. As such, there is a short period during which the cell has two, identical, fully formed nuclei.

The S phase of the cell cycle is the period during which DNA is replicated.

The G0 phase, sometimes called the resting or quiescent phase, is a phase of the cell cycle during which the cell remains in an inactive or dormant state. The G0 phase is often seen as an extension of the first growth phase (G1), during which the cell is not undergoing division or getting ready to undergo division, or it may be seen as a phase that happens separate from the cell cycle completely. Certain types of cells, such as nerve cells, enter into the G0 phase once they are mature, even though they continue to perform their designated functions. Cells enter this inactive stage from a checkpoint present in the G1 phase. Entrance into the G0 phase typically occurs in response to a deficiency of key nutrients and growth factors. The cell will remain in the this stage until these growth factors and nutrients are sufficient enough for the cell to continue through the cell cycle. The G0 phase is not always a component of the normal cell cycle.

There are various checkpoints throughout the cell cycle that regulate whether a cell will continue to divide. During the G1 phase there is a chemical checkpoint that determines whether a cell has the proper nutrients and growth factors to continue through the cell cycle, or whether it will enter the resting phase also known as the G0 phase. After DNA replication in the S (synthesis) phase, the cell enters the second growth phase, G2. In G2 there is the second checkpoint that will determine if the cell DNA replication was carried out successfully to further the division of the cell. If DNA replication is carried out properly the cell will enter the M (mitotic) phase of the cell cycle. Here, the cell will go through a series of phases that ultimately result in the separation of chromosomes. The success of mitosis is assessed at another checkpoint during metaphase (a sub-phase of the M phase). If everything is carried out properly, the cell will then undergo cytokinesis and result in two daughter cells. These will then enter the G1 phase to begin the cell cycle again.

There are various checkpoints throughout the cell cycle that regulate whether a cell will continue to divide. During the G1 phase there is a chemical checkpoint that determines whether a cell has the proper nutrients and growth factors to continue through the cell cycle, or whether it will enter the resting phase also known as the G0 phase. After DNA replication in the S (synthesis) phase, the cell enters the second growth phase, G2. In G2 there is the second checkpoint that will determine if the cell DNA replication was carried out successfully to further the division of the cell. If DNA replication is carried out properly, the cell will enter the M (mitotic) phase of the cell cycle. Here, the cell will go through a series of phases that ultimately result in the separation of chromosomes. The success of mitosis is assessed at another checkpoint during metaphase (a subdivision of the M phase). If everything is carried out properly, the cell will then undergo cytokinesis and resulting in two daughter cells.

During the G1 phase the cell grows and also carries out normal cellular functions. In the synthesis (S) phase the DNA is replicated resulting in two copies of each of the chromosomes. Upon entering the G2 phase the cell continue to grow and assess whether the DNA has been properly replicated to prepare for the mitosis (M) phase.

Mitosis, the next stage of the cell cycle, has four sequential steps: prophase, metaphase, anaphase, and telophase. In prophase, each chromosome becomes condensed and more visible, and there is the breakdown of the nuclear membrane and appearance of spindle fibers. In the next phase, metaphase, the chromosomes line up along the metaphasic plate. The spindle fibers are completely formed and are attached to each sister chromatid of the chromosomes. Next, during anaphase, the centromeres holding the sister chromatids together are divided and the sister chromatids are pulled apart by the spindle fibers to opposite poles of the diving cell. During the last phase of mitosis, telophase, the two sets of chromosomes reach the end of the opposing poles of the cell. This process is followed by the reformation of the nuclear envelope, uncoiling of the DNA, and disappearance of the spindle fibers. After the M phase is the separation of the cytoplasm known as cytokinesis, which results in two distinct daughter cells. These daughter cells enter into the G1 phase to begin the cell cycle again.

Mitosis begins with prophase, where the chromatin in the cell condenses into chromosomes. Prophase is followed by metaphase, characterized by the lining up of chromosomes along the metaphase plate. Anaphase is the next stage that begins with the separation of paired chromosomes (sister chromatids). The last stage of mitosis is the telophase, where the chromosomes are cordoned off into new nuclei and return to chromatin form. An easy way to remember this order is to use the acronym PMAT.

Note: Cytokinesis is not technically a part of mitosis, but it is often included. It is an event that directly follows mitosis in which the cytoplasm is divided into two daughter cells.

During the G1 phase the cell grows and also carries out normal cellular functions. In the synthesis (S) phase the DNA is replicated resulting in two copies of each of the chromosomes. Upon entering the G2 phase the cell continue to grow and assess whether the DNA has been properly replicated to prepare for the mitosis (M) phase.

Mitosis, the next cycle of the cell cycle, has four sequential stages: prophase, metaphase, anaphase, and telophase. In prophase, each chromosome becomes condensed and more visible, and there is the breakdown of the nuclear membrane and appearance of spindle fibers. In the next phase, metaphase, the chromosomes line up along the metaphasic plate. The spindle fibers are completely formed and are attached to each sister chromatid of the chromosomes. Next, during anaphase, the centromeres holding the sister chromatids together are divided and the sister chromatids are pulled apart by the spindle fibers to opposite poles of the diving cell. During the last phase of mitosis, telophase, the two sets of chromosomes reach the opposite poles of the cell. This is followed by the reformation of the nuclear envelope, uncoiling of the DNA, and disappearance of the spindle fibers. After the M phase is the separation of the cytoplasm known as cytokinesis, which results in two distinct daughter cells.

Cytokinesis is the period of the cell cycle during which the cytoplasm of the parent cell is divided and the parent cell completes division, resulting in two daughter cells.

During the G1 phase the cell grows and also carries out normal cellular functions. In the synthesis (S) phase the DNA is replicated, resulting in two copies of each of the chromosomes. Upon entering the G2 phase the cell continue to grow and assess whether the DNA has been properly replicated to prepare for the mitosis (M) phase.

Mitosis, the next stage of the cell cycle, has four sequential stages: prophase, metaphase, anaphase, and telophase. Cytokinesis begins during telophase and extends into the beginning of G1.

Replication of the DNA occurs during the S phase of interphase.

Interphase is essentially the first and longest phase of the cell cycle characterized by three distinct phases: growth phase 1 (G1), synthesis (S) phase, and srowth phase 2 (G2). During the G1 phase the cell grows and also carries out normal cellular functions. In the synthesis (S) phase the DNA is replicated, resulting in two copies of each of the chromosomes. Upon entering the G2 phase the cell continue to grow and assess whether the DNA has been properly replicated to prepare for the mitosis (M) phase.

Mitosis, the next stage of the cell cycle, has four sequential stages: prophase, metaphase, anaphase, and telophase. In prophase, each chromosome becomes condensed and more visible, and there is the breakdown of the nuclear membrane and appearance of spindle fibers. In the next phase, metaphase, the chromosomes line up along the metaphasic plate. The spindle fibers are completely formed and are attached to each sister chromatid of the chromosomes. Next, during anaphase, the centromeres holding the sister chromatids together are divided and the sister chromatids are pulled apart by the spindle fibers to opposite poles of the diving cell. During the last phase of mitosis, telophase, the two sets of chromosomes reach the opposite poles of the cell. This is followed by the reformation of the nuclear envelope, uncoiling of the DNA, and disappearance of the spindle fibers. After the M phase is the separation of the cytoplasm, known as cytokinesis, which results in two distinct daughter cells.