The restriction point is a decision point in G1 of the cell cycle. If the cell passes this point, the cell cycle will progress to the S phase. If the cell does not pass this point, there is likely a lack of stimulation from nutrients or growth factors, or some type of internal damage that must be corrected before the cell cycle can progress. Prolonged lack of progression past the restriction point can result in a quiescent cell, which enters the G0 phase and does not readily divide.

The other two cell cycle checkpoints occur after the G2 phase (before mitosis) and after metaphase (before anaphase).

The DNA will appear uncondensed and restricted to the nucleus. This is because a majority of the cells found in the sample will be in interphase, the longest stage of the cell cycle. Since it is the longest phase in the cell cycle, a majority of cells will be undergoing this phase at any given sample time. It is a point when the cell is undergoing normal cell processes and preparing for replication. During this phase, the DNA is uncondensed, allowing for transcription and giving DNA replication enzymes easy access to the nucleotide sequence.

DNA is condensed into 46 discrete chromosomes and restricted to the nucleus during early prophase, which makes up only a short period of the cell cycle. DNA is never condensed into 23 discrete chromosomes in somatic cells (such as epithelium), since 23 chromosomes would indicate a haploid cell. In humans, haploid cells only exist in the gametes, or sex cells. While prokaryotes have a single circular chromosome floating in the cytoplasm, such structure for a eukaryotic genome is not possible.

The G1 phase is the first stage of interphase. During this period, the cell grows and develops. In order to proceed to the next phase of interphase, the cell must pass the G1 checkpoint. In order for this to happen, cyclin proteins must be present and the proper cellular conditions must occur. If the cell passes the checkpoint it will proceed to the S phase, during which DNA replication occurs. If the cell fails to pass the checkpoint it can enter the G0 phase and become quiescent.

The G2 phase follows the S phase and ends with the G2 checkpoint. This checkpoint determines if the cell will enter mitosis, the M phase.

Interphase is the entirety of the cell cycle with the exception of mitosis. During the G1 period of interphase, the cell grows and produces many protein products to replicate organelles. G1 is followed by the S phase, during which DNA replication occurs. This is followed by the G2 phase, which prepares the cell for division.

The cell then enters prophase of mitosis, the M phase, during which chromosomes condense. Later in mitosis the sister chromatids are separated during anaphase. The G1 phase, S phase, and G2 phase are all portions of interphase, while the M phase corresponds to mitotic division.

Metabolism is the sum of all of the chemical and physical processes in a cell. Cell metabolism refers to any change in the cell.

Homeostasis is the resistance of the cell to change, and is responsible for maintaining a stable environment within the cell and body. Biochemistry is the sum of the chemical processes in the body. 

Interphase is the part of the cell cycle during which the cell grows, undergoes genome replication, and increases protein synthesis. Interphase includes three stages: gap 1 , synthesis (S), and gap 2 . During , the cell continually grows and is metabolically active. The synthesis stage is characterized by the replication of the genome.  features continued growth and the synthesis of proteins needed for mitosis, and DNA damage repair, if necessary. Following interphase, the cell enters mitosis and then cytokinesis to produce two identical daughter cells.

The genetic material of a cell is replicated during the S stage of interphase. The proper DNA replication is crucial to produce two identical daughter cells and to prevent genetic irregularities and disease. Any mistakes in DNA replication are fixed during the S stage as well. The S stage takes place between the G₁ and G₂ stages of interphase.

Cell division has two phases, nuclear division and division of the cytoplasm. The nuclear division, also known as karyokinesis, involves division of genetic material, involving the phases prophase, metaphase, anaphase, and telophase. Cytokensis begins during late anaphase and is the phase during which the cytoplasm divides.

During interphase, the cell is not dividing because the chromatin is enclosed within a nuclear envelope. Mitosis and meiosis are the phases in the cell cycle during which the cell is dividing. Last cellular and cytoplasmic division takes place during telophase and cytokinesis, respectively.

Cytokinesis is the division of the cytoplasm. Mitosis, also known as karyokinesis, is the division of the nucleus. Note that cytokinesis follows mitosis, and begins during late anaphase.