# Cell Division: Types, Process, Stages, and Functions > Understand cell division, including its major types, cell-cycle context, stages, functions, timing, and what happens when division is disrupted. Canonical URL: https://biologynotesonline.com/cell-division/ Author: Sourav Pan Last updated: October 1, 2026 ![Cell Division: Types, Process, Stages, and Functions](https://biologynotesonline.com/wp-content/uploads/2024/10/Major-Types-and-Modes-of-Cell-Division-1.webp) Cell division is a biological process by which a parent cell divides to produce two or more daughter cells. In this process, the cellular material is distributed into new cells. It is not same in all cells. The method, number of daughter cells, and chromosome condition depends on the type of cell and the type of division. In eukaryotic cells, cell division is generally completed by two linked events. First, nuclear division takes place, where the genetic material is separated. Then cytokinesis occurs, by which the cytoplasm is divided. So, one parent cell gives rise to daughter cells with their own cellular contents. Cell division is not the complete cell cycle. The cell cycle includes preparation also. Before the actual division, the cell passes through interphase, in which growth and copying of deoxyribonucleic acid (DNA) takes place. DNA replication occurs during the synthesis phase (S phase). The dividing part of a eukaryotic mitotic cell is the mitotic phase (M phase), where mitosis and cytokinesis are carried out. In eukaryotic discussion, mitosis and meiosis are the common forms of cell division. Mitosis usually forms genetically similar daughter cells. Meiosis is different. It has two nuclear divisions and produces cells with half chromosome number. In prokaryotic cells, the division is generally by binary fission. Here the chromosome is copied, the cell elongates, and the parent cell splits into two daughter cells. ## Types of Cell Division Cell division is a biological process by which a parent cell divides and forms daughter cells. Before the division of cell, deoxyribonucleic acid (DNA) is copied. The copied DNA is then distributed into the daughter cells. In eukaryotic cells, nuclear division is generally followed by the division of cytoplasm, which is called cytokinesis. ![Comparison of binary fission, mitosis, meiosis, and atypical amitosis showing their different chromosome and daughter-cell outcomes.](https://biologynotesonline.com/wp-content/uploads/2024/10/Major-Types-and-Modes-of-Cell-Division-1-1024x725.webp)Comparison of binary fission, mitosis, meiosis, and atypical amitosis showing their different chromosome and daughter-cell outcomes. The major types of cell division are as follows- - Binary fission - Mitosis - Meiosis - Amitosis ### 1. Binary Fission Binary fission- It is a simple type of cell division commonly found in prokaryotes, such as bacteria. The bacterial cell has no true nucleus. So, nuclear division like mitosis is not found in this process. In this division, the circular DNA first replicates from its origin of replication. The cell becomes elongated. The two copied chromosomes move towards opposite regions of the cell. After this, the plasma membrane and new cell wall material grow inward. A septum is formed. The parent cell is divided into two daughter cells. ### 2. Mitosis [Mitosis](https://biologynotesonline.com/mitosis/)- It is an equational type of cell division in which one parent cell forms two daughter cells. The daughter cells are genetically identical to the parent cell. The chromosome number remains same. It occurs mainly in somatic cells. It is used for growth, replacement of damaged cells and asexual reproduction in many organisms. Mitosis includes karyokinesis and cytokinesis. Karyokinesis means division of the nucleus. Cytokinesis means division of cytoplasm. #### Stages of Mitosis The following are the stages of mitosis- Prophase- In this stage, the chromosomes become short and thick. They are visible under microscope. The mitotic spindle also starts to form. Prometaphase- The nuclear envelope breaks down. Spindle fibres attach with the kinetochores of chromosomes. Metaphase- Chromosomes are arranged at the equatorial plate. It is also called the metaphase plate. In this stage, chromosomes are most clearly seen. Anaphase- The sister chromatids separate from each other. Each chromatid now behaves as a daughter chromosome and moves towards opposite poles. Telophase- Chromosomes reach at the opposite poles. The nuclear envelope is formed again around each set of chromosomes. The chromosomes also become thin and less visible. Cytokinesis- It is the division of cytoplasm. In animal cells, cleavage furrow is formed. In plant cells, cell plate is formed between two daughter nuclei. ### 3. Meiosis [Meiosis](https://biologynotesonline.com/meiosis/)- It is a reductional type of cell division in which one diploid parent cell forms four haploid daughter cells. It is associated with sexual reproduction and gamete formation. The daughter cells are not genetically identical. This variation is produced due to crossing over and separation of chromosomes. Meiosis has two successive divisions. These are meiosis I and meiosis II. DNA replication occurs only once before meiosis starts. #### Meiosis I Meiosis I- It is the reductional division. In this division, homologous chromosomes pair with each other. This pairing is referred to as synapsis. [Crossing over](https://biologynotesonline.com/crossing-over-types-mechanism-significance-example/) takes place during prophase I. During this process, genetic material is exchanged between homologous chromosomes. In anaphase I, homologous chromosomes separate and move to opposite poles. The chromosome number is reduced from diploid to haploid. #### Meiosis II Meiosis II- It is similar to mitotic division. Here, the sister chromatids separate from each other. At the end of meiosis II, four haploid cells are formed from one diploid parent cell. These cells carry different combinations of chromosomes. ![Meiosis sequence showing homolog pairing and crossing over, homolog separation in meiosis I, sister-chromatid separation in meiosis II, and four haploid cells.](https://biologynotesonline.com/wp-content/uploads/2024/10/Meiosis-I-and-Meiosis-II-Cell-Division-683x1024.webp)Meiosis sequence showing homolog pairing and crossing over, homolog separation in meiosis I, sister-chromatid separation in meiosis II, and four haploid cells. ### 4. Amitosis Amitosis- It is a direct type of nuclear division. Spindle formation does not occur in this process. The nucleus divides directly by nuclear fission. It is not the usual type of cell division in most eukaryotic cells. Amitosis is seen in some special eukaryotic cells, such as the macronucleus of ciliates. As spindle-based separation is absent, chromosome distribution may be unequal. ## Cell Division in the Cell Cycle The cell cycle is a genetically controlled series of changes that occur in a newly formed cell, by which it duplicates its contents, undergoes growth and divides to form two daughter cells. It is also called the "cell division cycle". The concept was given by Howard and Pelc (1953). The regular sequence of G1, S and G2 (interphase) followed by the M phase (mitotic phase) is called the cell cycle. ![Circular cell cycle showing G1, S, G2, and M phases, DNA replication in S phase, and mitosis followed by cytokinesis.](https://biologynotesonline.com/wp-content/uploads/2024/10/Cell-Division-in-the-Eukaryotic-Cell-Cycle-1024x1024.webp)Circular cell cycle showing G1, S, G2, and M phases, DNA replication in S phase, and mitosis followed by cytokinesis. The [cell cycle](https://biologynotesonline.com/cell-cycle/) has two major phases- a long non-dividing growth phase and a short dividing phase. The growth phase is the interphase (I phase) and the dividing phase is the mitotic phase (M phase). Interphase- Interphase is the period between two successive divisions. It is called the "resting stage", but it is in fact a period of great activity. The cell does not divide in this period. It is busy in preparation for division. It is also known as the preparatory phase. Interphase is classified into three subphases- G1 phase (post mitotic gap)- The cell grows in size. Different types of RNA (mRNA, tRNA, rRNA) and proteins are synthesized, and all cell organelles multiply. The duration of G1 varies from cell to cell. It is shorter in frequently dividing cells. A G1 cell has three options. It may continue the cycle and enter the S phase, it may stop and enter the quiescent phase (G0), or it may stop cycling and undergo differentiation. S phase (synthesis phase)- [Replication of deoxyribonucleic acid (DNA)](https://biologynotesonline.com/dna-replication-steps/) takes place in this phase. Each chromosome is duplicated, and the two copies remain attached to each other at the centromere. These copies are called the sister chromatids. The centrosome is also duplicated during the S phase. The DNA content of the cell doubles. The chromosome number remains the same. G2 phase (pre mitotic gap)- Proteins required for the manipulation of chromosomes are synthesized in this phase. The energy stores are replenished. The cell makes the final preparations for entering the M phase. The M phase- The actual cell division occurs during the M phase. Interphase only prepares the cell for it. The M phase has two major physical components in eukaryotes- karyokinesis (nuclear division) and [cytokinesis (division of cytoplasm)](https://biologynotesonline.com/cytokinesis/). In karyokinesis, the duplicated chromosomes are separated and distributed into two daughter nuclei. It is studied under four phases, namely prophase, metaphase, anaphase and telophase. Cytokinesis then divides the cytoplasm, and two daughter cells are formed. Cytokinesis may not occur in some cases. Cells with multiple nuclei (multinucleate cells) are then produced. Duration of cell division- There is no universal "speed of cell division". The timing varies substantially with the organism, the cell type, the developmental state and the surrounding conditions. When fast-dividing mammalian cells are grown in culture, the length of the cycle is approximately 24 hours. Cell division proper lasts for only about an hour in such a 24 hour cycle. In humans, cell turnover ranges from a few hours in early embryonic development to an average of two to five days for epithelial cells. Some specialized cells, like the cortical neurons and cardiac muscle cells, do not divide after maturation. They remain in the G0 phase for the entire lifetime. In the early embryos of fruit flies (Drosophila), the cell cycle is completed in about eight minutes. The longest portion of the cell cycle and the longest stage of mitosis are two different things. Longest portion of the cell cycle- Interphase is the longest portion. In a human cell, it occupies more than 95% of the total duration. G1 is generally the longest subphase of interphase. Longest stage of mitosis- Prophase is the longest phase of karyokinesis. But prophase covers only a small fraction of the whole cell cycle, because the M phase itself is very short. ## Stages of Mitotic Cell Division ![Sequential stages of mitosis showing chromosome condensation, spindle attachment, metaphase alignment, chromatid separation, nuclear reformation, and cytokinesis.](https://biologynotesonline.com/wp-content/uploads/2024/10/Stages-of-Mitosis-and-Cytokinesis-1024x341.webp)Sequential stages of mitosis showing chromosome condensation, spindle attachment, metaphase alignment, chromatid separation, nuclear reformation, and cytokinesis. Mitosis is completed in two steps- karyokinesis (nuclear division) and cytokinesis. Karyokinesis is studied under four phases, namely prophase, metaphase, anaphase and telophase. Cytokinesis follows at the end. Prophase- Prophase (Gk. pro- first, phase- stage) is the first and the longest phase of karyokinesis. It is divided into three substages- early prophase, mid prophase and late prophase. In early prophase, the chromatin fibres condense to form elongated chromosomes. The chromosomes become visible under the light microscope due to coiling. The nucleus appears like a "ball of wool". Viscosity of the cytoplasm increases. In animal cells, the duplicated centrioles start moving towards the opposite poles. Fine microtubular fibrils radiate out from each centriole. These are called the astral rays, and they form an aster around each centriole. During late prophase, the nuclear envelope starts breaking down. The nucleolus and other cell organelles (mitochondria, Golgi complex, endoplasmic reticulum (ER) etc.) disappear. Spindle fibres appear around the nucleus. The spindle poles are formed without asters in plant cells and with asters in animal cells. Metaphase- In metaphase (Gk. meta- after, phase- stage), the spindle fibres get connected to the disc shaped structures present at the surface of the centromere. These structures are called the kinetochores. The fibres contract and bring the chromosomes over the equator. This phenomenon is known as congression. The centromeres of all the chromosomes lie on the equator and form an apparent plate called the metaphase plate (equatorial plate), while the arms are directed towards the poles. Smaller chromosomes lie towards the centre and the larger ones remain peripheral. Metaphase is the best phase to count the total number of chromosomes of any species. Morphology of the chromosomes is also studied in this phase. Anaphase- The centromere of each chromosome divides into two. The sister chromatids separate and are now called the daughter chromosomes. Spindle fibres attached to the centromeres shorten and pull them towards the opposite poles. The centromere leads the path and the arms trail behind. So the chromosomes appear V-shaped, L-shaped, J-shaped or I-shaped, depending upon the position of the centromere. At the end, two groups of chromosomes are formed, one at each pole. The number and types of chromosomes at each pole remain the same as in the parent nucleus. Telophase- The chromosomes reach the opposite poles and start uncoiling. Chromatin is formed again. A new nuclear envelope is formed around each set of chromosomes, and the nucleolus reappears. The spindle disappears. Two daughter nuclei are formed. This phase is just the reverse of prophase. The Golgi complex and the ER are also reformed. Cytokinesis- Mitosis ends with the division of cytoplasm, known as cytokinesis (Gk. cytos- hollow or cell, kinesis- movement). It starts towards the middle of anaphase and is completed with the telophase. If nuclear division takes place without cytoplasmic division, a multinucleate condition (syncytium) is produced. In animal cells, a contractile ring of actin filaments is formed just inside the plasma membrane at the former metaphase plate. The ring pulls the equator of the cell inwards and a fissure is produced. This fissure is called the cleavage furrow. The furrow deepens as the actin ring contracts, and the parent cell is finally cleaved into two daughter cells. This method is known as the cleavage method. Plant cells have a rigid wall, so cytokinesis occurs by cell plate formation. During interphase, the Golgi apparatus accumulates enzymes, structural proteins and glucose molecules. During telophase, the Golgi vesicles are transported on microtubules to the equator and form a vesicular structure called the phragmoplast. The vesicles fuse and coalesce from the centre towards the periphery. This structure is called the cell plate. The plate enlarges and finally merges with the cell walls of the parent cell. A new cell wall is produced between the two daughter cells. ![Comparison of animal cytokinesis by contractile-ring cleavage and plant cytokinesis by phragmoplast-guided cell plate formation.](https://biologynotesonline.com/wp-content/uploads/2024/10/Animal-and-Plant-Cell-Cytokinesis-1024x427.webp)Comparison of animal cytokinesis by contractile-ring cleavage and plant cytokinesis by phragmoplast-guided cell plate formation. ## Regulation of Cell Division Cell division is controlled at different stages of the cell cycle. Different regulatory proteins, cyclins, cyclin-dependent kinases and checkpoints take part in this control, and the cell moves into the next stage only after the required cellular events are completed. ![Cell-cycle control pathway showing G1/S, G2/M, and spindle checkpoints with cyclin-CDKs, p53-p21, WEE1-CDC25, MCC, APC/C, separase, and cohesin.](https://biologynotesonline.com/wp-content/uploads/2024/10/Cell-Cycle-Checkpoints-and-Regulation-of-Cell-Division-1024x427.webp)Cell-cycle control pathway showing G1/S, G2/M, and spindle checkpoints with cyclin-CDKs, p53-p21, WEE1-CDC25, MCC, APC/C, separase, and cohesin. - Cyclin-CDK system- Cyclins and cyclin-dependent kinases (CDKs) are the major proteins involved in regulation of cell division. CDKs become active after binding with their particular cyclins. The active cyclin-CDK complex phosphorylates different target proteins and controls entry into deoxyribonucleic acid (DNA) replication or mitosis. Cyclins are formed and degraded at different stages. So, CDK activity changes during the cell cycle. - Growth signals- In mammalian cells, mitogenic signals from outside the cell stimulate the formation of D-type cyclins. Cyclin D binds with CDK4 or CDK6 and the formed complex acts during G1 phase. It phosphorylates retinoblastoma protein (RB), which reduces the inhibitory effect of RB on E2F and permits expression of genes required for S phase. - CDK inhibitors- Cyclin-dependent kinase inhibitors (CKIs) bind with cyclin-CDK complexes and decrease their activity. p21 and p27 inhibit different CDKs, whereas proteins of INK4 family mainly act on CDK4 and CDK6. - G1/S checkpoint- This checkpoint acts before DNA replication. When DNA is damaged, p53 becomes active and increases the formation of p21. p21 inhibits cyclin-CDK activity. RB remains in its growth-suppressing state and entry of the cell into S phase is delayed. - S-phase control- DNA replication is also checked during S phase. Replication stress or damaged DNA activates checkpoint signalling, which can decrease CDK activity and slow down further DNA replication until the problem is dealt with. - G2/M checkpoint- Entry into mitosis is stopped if DNA replication is incomplete or the DNA is damaged. Cyclin B-CDK1 is kept inactive by inhibitory phosphorylation. WEE1 and CDC25 proteins are involved in its regulation. During DNA damage, CDC25 activity is inhibited by checkpoint signalling and activation of CDK1 is delayed. - Spindle checkpoint- The [spindle assembly checkpoint (SAC)](https://biologynotesonline.com/checkpoints-in-the-cell-cycle-g1-g2-metaphase-spindle-checkpoints/) acts during mitosis. It checks whether chromosome kinetochores are properly attached with spindle microtubules. An unattached kinetochore produces a checkpoint signal and the mitotic checkpoint complex (MCC) is formed. MCC inhibits cell division cycle 20 (CDC20), which prevents early activation of the anaphase-promoting complex/cyclosome (APC/C). Anaphase is delayed. - APC/C activity- When chromosome attachment is completed properly, inhibition of APC/C-CDC20 is removed. APC/C causes ubiquitin-dependent degradation of securin and cyclin B. Degradation of securin activates separase, which cleaves cohesin holding the sister chromatids together. Sister chromatids separate. Cyclin B degradation also decreases CDK1 activity during mitotic exit. ## Consequences of Division Errors ![Pathway showing how chromosome mis-segregation can produce aneuploid cells or micronuclei and contribute to DNA damage and genomic instability.](https://biologynotesonline.com/wp-content/uploads/2024/10/Consequences-of-Cell-Division-and-Chromosome-Segregation-Errors-683x1024.webp)Pathway showing how chromosome mis-segregation can produce aneuploid cells or micronuclei and contribute to DNA damage and genomic instability. The following are the important consequences of errors in cell division- - Unequal chromosome separation- Sometimes chromosomes are not separated equally during mitosis or meiosis. One daughter cell gets extra chromosome and another cell gets less chromosome. This error is also called chromosome mis-segregation. It may occur due to wrong spindle attachment. - It may occur when the checkpoint does not stop the cell. - It gives unequal genetic material to daughter cells. - Aneuploidy- Aneuploidy is the condition where a cell contains abnormal number of chromosomes. It is formed when chromosomes or chromatids fail to separate properly.Some aneuploid cells die. Some cells can remain alive, but their normal function gets disturbed. - [Non-disjunction](https://biologynotesonline.com/nondisjunction-types-causes-consequences-examples/)- It is the failure of homologous chromosomes or sister chromatids to separate during cell division.In meiosis, non-disjunction may produce abnormal gametes. These gametes may contain one extra chromosome or one chromosome less. If such gamete takes part in fertilization, the zygote also gets abnormal chromosome number. - Failed spindle attachment- The chromosomes should attach with spindle fibres through kinetochore region. If this attachment is not proper, the chromosome may move to wrong pole.The spindle checkpoint normally stops this. But if the checkpoint fails, anaphase may start with wrong attachment. - Lagging chromosome- Sometimes a chromosome or chromosome fragment remains behind during chromosome movement. It does not reach the pole at proper time.This chromosome may not enter the main daughter nucleus. A small extra nucleus may be formed from it. - Micronucleus formation- Micronucleus is a small nucleus-like structure formed outside the main nucleus. It may contain a lagging chromosome or chromosome fragment.The deoxyribonucleic acid (DNA) present in micronucleus is not always replicated normally. It may also undergo damage in next cell cycle. - DNA damage transfer- If damaged DNA is not repaired before division, it may be passed into daughter cells. The error then moves to next cell generation.This is harmful in repeated cell division. Damaged DNA can be copied again and again. - Mutation formation- Mutation may be formed when DNA damage is copied or repaired wrongly. It can affect a gene, chromosome segment, or regulatory region.Some mutations do not show strong effect. Some mutations change protein formation and cell behaviour. - Chromosome breakage- Division error may produce broken chromosome parts. The broken ends may join wrongly with other chromosome parts.This may form chromosome rearrangement. Deletion, duplication, inversion and translocation can occur in this way. - Genomic instability- Genomic instability means the genome becomes unstable. More DNA errors and chromosome errors are produced. Chromosome number may become abnormal. - Chromosome structure may be changed. - DNA damage may accumulate. - Later divisions may produce more errors. - Cell-cycle arrest- If the division error is detected, the cell cycle may stop for some time. This stopping gives time for repair.Checkpoints are involved here. If the error is corrected, the cell may continue division. - Cell death- Severely damaged cells may undergo cell death. This removes cells having heavy DNA damage or abnormal chromosome content.In multicellular organisms, this process prevents the abnormal cell from multiplying further. - Developmental defects- During embryonic development, division errors can disturb normal body formation. A small error in early embryo may affect many later cells.Wrong chromosome number may stop development. Severe DNA damage may also reduce survival of embryo. - Abnormal gamete formation- Errors in meiotic division produce abnormal gametes. The gametes may carry extra or missing chromosomes.Such gametes are genetically unbalanced. Fertilization with such gamete may produce abnormal zygote. - Loss of tissue function- Some tissues need regular cell replacement. Blood-forming tissue, skin and intestinal lining are examples.If division errors increase in these tissues, newly formed cells may not work properly. Tissue repair may become slow. - Uncontrolled proliferation- When normal cell-cycle control is lost, the cell may continue to divide. It may not respond to normal stop signals.The abnormal cells increase in number. An abnormal cell mass can be formed. - Cancer formation- Cancer may develop when cell division errors combine with failure of DNA repair, checkpoint control and cell death. It is not only fast cell division.Cell-cycle genes, DNA repair genes and growth-control pathways may be changed. The abnormal cells survive and keep dividing. ## Functions of Cell Division The following are the important functions of cell division- - Growth- Cell division helps in increasing the number of cells in a multicellular organism. A zygote divides repeatedly and forms embryo, then tissues and organs are formed. The body size increases by this process. - Cell replacement- Old and worn-out cells are replaced by new cells. Skin cells, blood cells and lining cells of intestine are continuously replaced. These cells do not stay for the whole life of the organism. - Repair of damaged tissues- Cell division is used to repair injured or damaged tissues. When a wound is formed, nearby cells divide and fill up the damaged area. New cells are produced at the site. - Regeneration- In some organisms, lost body parts can be formed again by repeated cell division. It is seen in organisms like Hydra, planaria and some lizards. The dividing cells produce new tissues in the damaged region. - Asexual reproduction- Many unicellular organisms reproduce by cell division. In bacteria, binary fission produces two daughter cells from one parent cell. In yeast, budding also depends on cell division. - Formation of gametes- Meiosis is used for the formation of gametes. It reduces the chromosome number to half. These [haploid gametes](https://biologynotesonline.com/gametogenesis/) later fuse during fertilization. - Maintenance of chromosome number- In mitosis, the chromosome number remains same in daughter cells. The genetic material is equally distributed. This keeps the chromosome number constant in body cells. - Genetic continuity- Deoxyribonucleic acid (DNA) is copied before cell division, and the copied DNA is passed into daughter cells. The daughter cells receive the hereditary information from the parent cell. This maintains continuity from one cell generation to another. - Genetic variation- Meiosis produces variation in sexually reproducing organisms. Crossing over and independent assortment change the combination of genes. The gametes formed are not genetically identical. - Development- Cell division is required during development of an organism. After fertilization, the zygote divides many times. These cells later differentiate and form different tissues, organs and body systems. - Healing- Healing of cuts, wounds and broken tissues depends on mitotic division. New cells cover the injured surface. Some connective tissue cells also divide and help in repair. - Replacement in blood and immune cells- Bone marrow cells divide continuously and produce new blood cells. Some immune cells also multiply after infection. This helps the body to maintain cell population during normal and diseased condition. ## Cell Division- At a Glance The following table gives a quick summary of cell division- TopicAt a glanceDefinitionCell division is a process by which a parent cell divides and forms new daughter cells.Main purposeIt is used for growth, repair, replacement, reproduction and formation of gametes.Before divisionDeoxyribonucleic acid (DNA) is copied before the cell divides. This helps daughter cells to receive genetic material.In cell cycleCell division occurs mainly during mitotic phase (M phase). Before this, the cell passes through interphase.InterphaseIt includes gap 1 phase (G1 phase), synthesis phase (S phase), and gap 2 phase (G2 phase). It is the preparatory part of cell cycle.S phaseDNA replication takes place in S phase. Each chromosome forms two sister chromatids.M phaseIt is the division phase. It includes nuclear division and cytokinesis.Nuclear divisionThe nucleus divides. In body cells, this division is mitosis. In gamete-forming cells, it is meiosis.CytokinesisThe cytoplasm divides and two separate daughter cells are formed.MitosisOne parent cell forms two genetically identical daughter cells. Chromosome number remains same.MeiosisOne diploid parent cell forms four haploid daughter cells. Chromosome number becomes half.Binary fissionIt is common in bacteria. One parent cell divides into two daughter cells.AmitosisIt is a direct nuclear division without proper spindle formation. It is seen only in some special cells.Stages of mitosisProphase, prometaphase, metaphase, anaphase, telophase and cytokinesis are commonly described.ProphaseChromosomes become condensed and visible. Spindle formation starts.PrometaphaseNuclear envelope breaks down. Spindle fibres attach with kinetochores.MetaphaseChromosomes are arranged at the metaphase plate.AnaphaseSister chromatids separate and move to opposite poles.TelophaseChromosomes reach poles. Nuclear envelope is formed again.Cytokinesis in animal cellCleavage furrow is formed. The cell membrane moves inward.Cytokinesis in plant cellCell plate is formed. Later it becomes new cell wall.RegulationCell division is controlled by checkpoints, cyclins, cyclin-dependent kinases (CDKs), DNA repair and stop signals.CheckpointsThese are control points that check DNA damage, DNA replication and chromosome attachment.G1 checkpointIt checks cell size, nutrients, growth signals and DNA damage.G2 checkpointIt checks whether DNA replication is complete or not.Spindle checkpointIt checks whether chromosomes are properly attached with spindle fibres.Division errorsErrors may cause unequal chromosome separation, aneuploidy, DNA damage transfer and genomic instability.Cancer linkLoss of normal cell-cycle control can allow abnormal cells to divide continuously.Longest partInterphase usually takes the longest time in the whole cell cycle.Fastest or slowest divisionThere is no fixed speed of cell division. It differs with organism, cell type, age, tissue and condition.