Interphase and part of Telophase of HT1080

Interphase is the portion of the

cell cycle The cell cycle, or cell-division cycle, is the series of events that take place in a cell that cause it to divide into two daughter cells. These events include the duplication of its DNA (DNA replication) and some of its organelles, and sub ...

that is not accompanied by visible changes under the microscope, and includes the G1, S and G2 phases. During interphase, the cell grows (G1), replicates its DNA (S) and prepares for mitosis (G2). A cell in interphase is not simply quiescent. The term quiescent (i.e. dormant) would be misleading since a cell in interphase is very busy synthesizing proteins, copying DNA into RNA, engulfing extracellular material, processing signals, to name just a few activities. The cell is quiescent only in the sense of cell division (i.e. the cell is out of the cell cycle, G0). Interphase is the phase of the

in which a typical

cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery ...

spends most of its life. Interphase is the 'daily living' or metabolic phase of the cell, in which the cell obtains nutrients and metabolizes them, grows, replicates its DNA in preparation for mitosis, and conducts other "normal" cell functions. Interphase was formerly called the resting phase. However, interphase does not describe a cell that is merely resting; rather, the cell is living and preparing for later cell division, so the name was changed. A common misconception is that interphase is the first stage of mitosis, but since mitosis is the division of the

nucleus Nucleus ( : nuclei) is a Latin word for the seed inside a fruit. It most often refers to: *Atomic nucleus, the very dense central region of an atom * Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA Nucl ...

prophase Prophase () is the first stage of cell division in both mitosis and meiosis. Beginning after interphase, DNA has already been replicated when the cell enters prophase. The main occurrences in prophase are the condensation of the chromatin ret ...

is actually the first stage. In interphase, the cell gets itself ready for mitosis or

meiosis Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately r ...

. Somatic cells, or normal diploid cells of the body, go through mitosis in order to reproduce themselves through cell division, whereas diploid

germ cell Germ or germs may refer to: Science * Germ (microorganism), an informal word for a pathogen * Germ cell, cell that gives rise to the gametes of an organism that reproduces sexually * Germ layer, a primary layer of cells that forms during emb ...

s (i.e., primary

spermatocyte Spermatocytes are a type of male gametocyte in animals. They derive from immature germ cells called spermatogonia. They are found in the testis, in a structure known as the seminiferous tubules. There are two types of spermatocytes, primary and ...

s and primary

oocyte An oocyte (, ), oöcyte, or ovocyte is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The femal ...

s) go through

in order to create haploid

gametes A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce ...

(i.e., sperm and

ova , abbreviated as OVA and sometimes as OAV (original animation video), are Japanese animated films and series made specially for release in home video formats without prior showings on television or in theaters, though the first part of an OVA s ...

) for the purpose of sexual reproduction.

Stages of interphase

There are three stages of cellular interphase, with each phase ending when a cellular checkpoint checks the accuracy of the stage's completion before proceeding to the next. The stages of interphase are: * G₁ (Gap 1), in which the cell grows and functions normally. During this time, a high amount of protein synthesis occurs and the cell grows (to about double its original size) – more organelles are produced and the volume of the

cytoplasm In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. ...

increases. If the cell is not to divide again, it will enter G₀. * Synthesis (S), in which the cell synthesizes its DNA and the amount of DNA is doubled but the number of chromosomes remains constant (via

semiconservative replication Semiconservative replication describe the mechanism of DNA replication in all known cells. DNA replication occurs on multiple origins of replication along the DNA template strand (antinsense strand). As the DNA double helix is unwound by helicase, ...

). * G₂ (Gap 2), in which the cell resumes its growth in preparation for division. The mitochondria divide and the cell continues to grow until mitosis begins. In plants, chloroplasts also divide during G2. * In addition, some cells that do not divide often or ever, enter a stage called G₀ (Gap zero), which is either a stage separate from interphase or an extended G₁. The duration of time spent in interphase and in each stage of interphase is variable and depends on both the type of cell and the species of organism it belongs to. Most cells of adult mammals spend about 24 hours in interphase; this accounts for about 90%-96% of the total time involved in cell division. Interphase includes G1, S, and G2 phases. Mitosis and

cytokinesis Cytokinesis () is the part of the cell division process during which the cytoplasm of a single eukaryotic cell divides into two daughter cells. Cytoplasmic division begins during or after the late stages of nuclear division in mitosis and mei ...

, however, are separate from interphase. DNA double-strand breaks can be repaired during interphase by two principal processes. The first process,

non-homologous end joining Non-homologous end joining (NHEJ) is a pathway that repairs double-strand breaks in DNA. NHEJ is referred to as "non-homologous" because the break ends are directly ligated without the need for a homologous template, in contrast to homology direc ...

(NHEJ), can join the two broken ends of DNA in the G1, S and G2 phases of interphase. The second process,

homologous recombination Homologous recombination is a type of genetic recombination in which genetic information is exchanged between two similar or identical molecules of double-stranded or single-stranded nucleic acids (usually DNA as in cellular organisms but may ...

al repair (HRR), is more accurate than NHEJ in repairing double-strand breaks. However HRR is only active during the S and G2 phases of interphase when

DNA replication In molecular biology, DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. DNA replication occurs in all living organisms acting as the most essential part for biological inheritanc ...

is either partially or fully accomplished, since HRR requires two adjacent

homologous chromosomes A couple of homologous chromosomes, or homologs, are a set of one maternal and one paternal chromosome that pair up with each other inside a cell during fertilization. Homologs have the same genes in the same loci where they provide points alon ...

Interphase within sequences of cellular processes

Interphase and the cell cycle

When G₂ is completed, the cell enters a relatively brief period of nuclear and cellular division, composed of mitosis and cytokinesis, respectively. After the successful completion of mitosis and cytokinesis, both resulting

daughter cell Cell division is the process by which a parent cell divides into two daughter cells. Cell division usually occurs as part of a larger cell cycle in which the cell grows and replicates its chromosome(s) before dividing. In eukaryotes, there ar ...

s re-enter G₁ of interphase. In the

, interphase is preceded by

telophase Telophase () is the final stage in both meiosis and mitosis in a eukaryotic cell. During telophase, the effects of prophase and prometaphase (the nucleolus and nuclear membrane disintegrating) are reversed. As chromosomes reach the cell poles, ...

and

of the

M phase The cell cycle, or cell-division cycle, is the series of events that take place in a cell that cause it to divide into two daughter cells. These events include the duplication of its DNA (DNA replication) and some of its organelles, and subs ...

. In alternative fashion, interphase is sometimes interrupted by G₀ phase, which, in some circumstances, may then end and be followed by the remaining stages of interphase. After the successful completion of the G₂ checkpoint, the final checkpoint in interphase, the cell proceeds to

, or in plants to

preprophase Preprophase is an additional phase during mitosis in plant cells that does not occur in other eukaryotes such as animals or fungi. It precedes prophase and is characterized by two distinct events: #The formation of the preprophase band, a dense ...

, which is the first stage of mitosis. G₀ phase is viewed as either an extended G₁ phase where the cell is neither dividing nor preparing to divide, or as a distinct

quiescent Quiescence (/kwiˈɛsəns/) is a state of quietness or inactivity. It may refer to: * Quiescence search, in game tree searching (adversarial search) in artificial intelligence, a quiescent state is one in which a game is considered stable and unl ...

stage which occurs outside of the cell cycle.

Interphase and other cellular processes

gamete A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce ...

production, interphase is succeeded by

. In

programmed cell death Programmed cell death (PCD; sometimes referred to as cellular suicide) is the death of a cell (biology), cell as a result of events inside of a cell, such as apoptosis or autophagy. PCD is carried out in a biological process, which usually confers ...

, interphase is followed or preempted by apoptosis.

References

{{cell cycle Mitosis Cell biology

Stages of interphase

Interphase within sequences of cellular processes

Interphase and the cell cycle

Interphase and other cellular processes

See also

References