Christopher SmithProfessor JohnsonBio 111230 March 2019 The Cell CycleHave you ever wondered how a kitten could turn into a full adult cat? If so, you are more than likely familiar with the impression of a life cycle. Cats go through some similar life cycle transition as we do. We watch something that looks like an ordinary baby kitten turn into a magnificent creature that runs free in the wind. A life cycle is a series of steps that one goes through from the time they born until the time it reproduces.
The cell cycle is a life cycle of the cell. It is the sequence of steps a cell experiences between its development by the division of a mother cell to make two daughter cells. With the aim to divide, a cell must complete quite a few significant responsibilities. These responsibilities include: it must grow, then duplicate its genetic material, and divide into two daughter cells. Cells complete these responsibilities in an ordered series of steps that make the cell cycle.
This is a cycle because at the end, the two daughter cells must start the exact same process repeatedly from the beginning. The cell cycle is a significant procedure which a single-celled fertilized egg grows into a mature organism, as well as where blood cells, skin, hair and are renewed. In eukaryotes, the cell cycle is divided into three main stages: interphase and the mitosis and cytokinesis. Each partaking vital steps to correctly complete the cycle. Interphase is the period when a cell is getting ready to duplicate itself. The cell spends most of its life in this phase because of the amount of activities occurring in the cell. A cell must complete a variation of events for reproduction. The cell makes more cytoplasm and a large supply of proteins. When done, it prepares for the three points of Interphase: G1, S, and G2. The total time spent in interphase depends on the cell and the class it belongs to. Most cells of animals spend 24 hours in interphase. That’s 95% of the time in cell division. Interphase is always misinterpreted as the first stage of mitosis.Mitosis is the parting of the nucleus, prophase is the initial stage. In interphase, the cell prepares for mitosis. This procedure includes the doubling of DNA and organelles in the cell. In result, each daughter cell has similar content inside. Although they may perform those roles before mitosis begins, some organelles have very detailed roles that helps mitosis. Before the process starts, a cell must make sure that it has enough energy molecules and membrane building blocks.There are three organelles that perform precise roles so that mitosis happens: the smooth endoplasmic reticulum, the mitochondria and the centrosomes. The smooth ER and mitochondria do their jobs during interphase before mitosis happens. Centrosomes double during Interphase during mitosis.The endoplasmic reticulum is a network of connected tunnels and pouches. One of the functions of the smooth endoplasmic reticulum is to make phospholipids. Phospholipids are the building blocks that make up the membranes of a cell. They consume an electrically charged head and an oily, Aqua-phobic tail. The phospholipids make bilayers which hide the tails in the middle exposing the charged head on either side. The number of phospholipids doubles during the S phase. This is important because the cell splits into two cells during mitosis. This means there needs to be enough material to make two separate cells.The mitochondria are organelles that are great at producing lots of ATP. The mitochondria are powered by Adenosine triphosphate. Adenosine triphosphate is an organic chemical that provides energy to drive processes in living cells, many mitochondria organelles are required in mitosis. The S phase is when the cell makes a copy of its entire DNA. They will be evenly divided during mitosis. The cell must have enough ATP molecules, before the cell commits to the S phase. The mitochondria fuses with each other to form a network before a cell enters the S phase. This network produces a lot more ATP than a single mitochondrion could ever produce.Centrosomes are proteins that make spindle fibers. These fibers are called microtubules help motor proteins move along the cell. Centrosomes double during S phase because mitosis give one centrosome to each daughter cell. The responsibility of the centrosomes is to form a north pole and a south pole across cell before mitosis is finished. The north pole and the south pole are connected by spindle fibers. They start at one centrosome and reach across to the other side. The spindle fibers help pull DNA apart while the cell divides into two.The G1 phase is when the cell makes a lot more protein than usual so it can grow to the proper size. During this phase, this is also the period when cells makes a lot more ribosomes. Ribosomes are the protein makers of the cell. The cell will not leave the G1 phase and go in the S phase until it has enough ribosomes. The ending of the G1 phase is also when the mitochondria combine into a network of mitochondria. This helps these organelles better at producing energy molecules rather than only having one.The S phase is when the cell copies its DNA but does not exist by itself. DNA is packaged by proteins. New packaging proteins must be made to wrap the copied DNA. The creation of histone proteins and the copying of DNA are linked. Stopping one process will stop the other. S phase also produces a lot more phospholipids than usual. Phospholipids make up the cell membrane. The amount of phospholipid doubles in the S stage.The G2 phase is when the cell replicates its organelles. The organelles and DNA need to be divided. G2 is the final opportunity for the cell to create additional protein in preparation for separation. The cell has double the total of DNA during G2 than it did throughout G1. G2 is essential for the cell to make sure that all the DNA is complete. The G2 to mitosis changeover is the last checkpoint before the cell binds to going in to mitosis.Mitosis is the main instrument organisms make new cells is through cell separation. Mitosis is the development by which a cell separates its reproduced DNA, eventually separating its nucleus into two. During the procedure, a single parent cell divides and produces daughter cells. In this manner, parent cells pass on its genetic material to each daughter cells. Primary nevertheless, cells essential replicate their DNA. The origin of the word Prophase comes from both the Latin and Greek words. Pro meaning before, forward, forth. In Old English pro means before, for, and on account of. Phase means appearance Prophase is the first phase of mitosis. This is a stage of mitosis where the chromatin shortens into chromosomes in which chromatin becomes noticeable. This is called chromatin condensation. The genetic material has been imitated in interphase, there are two reproductions of each chromosome in the cell already. Chromosomes cannot be seen in the interphase. Nuclear envelope along with nucleoli disappear. This leads to centrioles completely migrating towards their own poles. Mitotic apparatus is organized, and cytoplasm becomes stickier. The chromatin material gets reduced by folding and chromosomes seem thin and, in the end, become thick, containing two chromatids committed.The origin of the word Metaphase comes from the Greek language. Meta means in the middle. Phase means appearance. In Metaphase chromosomes become completely thick containing chromatid. Chromatids are attached to centromere. The cells have distinct part, the kinetochore, where kinetochore fibers of the mitotic apparatus go together. The kinetochore fibers of spindle are attached to the kinetochore area of chromosomes and make parallel at the equator of the spindle creating metaphase plate. Each kinetochore receives two fibers, each from contradictory poles. The origin of the word Anaphase comes from the Greek language. Ana means “again, anew,” “up, on, upon; up to, toward; throughout; back, backwards; again, anew. Anaphase It is a significant stage of mitosis. The kinetochore fibers of spindle pact in the direction of their corresponding poles and apply strength which split up the two chromatids from centromere. Thus, two sister chromatids are shaped. Half of them transfer to one pole and alternative half towards another pole.Telophase word origin comes from the Greek language. The Greek world telo is a form of tele which means far off, occurring exceptionally”. In Telophase, the chromosomes reach to their individual pole. The chromosome starts unfolding and become chromatin material. Mitotic apparatus starts disappearing while nucleus and nucleoli appears and thus two nucleoli are formed at each pole of the cell.The Cytokinesis word origin comes from the Greek Language. Cyto meaning of a cell or cells. Kinesis meaning movement; motion. Cytokinesis is not a stage of mitosis. It is the final stage of the cell cycle. Cytokinesis is a phase in which the whole cell divides to form two daughter cells. It ensures that the chromosome number is upheld from one generation to the next. At this phase microtubules send signals to the equatorial region of cell which activate some action and myosin to form contractile ring. This contractile ring form, cleavage in the center of the cell. This excavates progressively and eventually split the parent cell into two daughter cells.The cell cycle is a sequence of events leading to its detachment and doubling of its DNA to produce two new daughter cells. The purpose of mitosis is involved with growth, repair and replacement. Mitosis allows for development and expansion of the individual. This also allows replacement and repair of damaged and worn out cells. Each new cell is identical to the original cell. This allows all cells in the body to be genetically identical. For eukaryotes, the cell cycle is needed to replicate cells to replace those that were damaged. Plants require the cell cycle to grow and provide life for every other organism on earth. Cited workAlberts, Bruce. An Overview of the Cell Cycle. Molecular Biology of the Cell. 4th Edition., U.S. National Library of Medicine, 1 Jan. 1970, www.ncbi.nlm.nih.gov/books/NBK26869/. Cregan, Elizabeth R. All about Mitosis and Meiosis. Compass Point Books, 2010. Smith, C. A., and Edward J. Wood. Cell Biology. Stanley Thornes, 1999. What Is Mitosis? DNA Encyclopedia, 25 Oct. 2016, whatisdna.net/wiki/what-is-mitosis/.Alberts B, Johnson A, Lewis J, et al. Molecular Biology of the Cell. 4th edition. New York: Garland Science; 2002. The Endoplasmic Reticulum. 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