Cell cycle
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Cell cycle
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Alkylating agents p. 445
in cell cycle p. 443
Antimetabolites p. 443
in cell cycle p. 443
Azathioprine
in cell cycle p. 444
Bleomycin p. 447
in cell cycle p. 443
Cancer drugs
cell cycle p. 443
Carmustine p. 445
in cell cycle p. 443
Cell cycle phases p. 44
Cisplatin p. 445
in cell cycle p. 443
Cladribine p. 443
in cell cycle p. 443
Cytarabine p. 443
in cell cycle p. 443
Cytoplasm
cell cycle phase p. 44
Etoposide p. 446
in cell cycle p. 443
5-fluorouracil p. 443
in cell cycle p. 443
Hydroxyurea p. 444
in cell cycle p. 443
Irinotecan p. 446
in cell cycle p. 443
Lomustine p. 445
in cell cycle p. 445
Methotrexate p. 443
in cell cycle p. 443
Microtubule inhibitors p. 445
in cell cycle p. 443
Paclitaxel p. 445
in cell cycle p. 443
6-mercaptopurine p. 444
in cell cycle p. 444
Teniposide p. 446
in cell cycle p. 443
Vinblastine p. 445
in cell cycle p. 443
Vincristine p. 445
in cell cycle p. 443
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The cell cycle refers to the events that somatic cells - which includes all of the cells in our bodies except the reproductive cells - go through from the moment they’re formed until the moment they divide in two identical daughter cells.
This cycle varies in length depending on the type of cell - for rapidly dividing cells, like skin cells, it takes less than a day, whereas for other cells, like liver cells, the cell cycle can last years.
The cell cycle has two phases: interphase, and mitosis.
Interphase the longest part of the cell cycle, and it’s a state of preparation, during which the cell carries out its cell functions, grows and replicates its DNA to prepare for mitosis - or cellular division.
After a parent cell divides, each of the two daughter cells enter interphase again.
Now, interphase can further be broken down in three subphases: G1, S, and G2. G1 stands for “gap” or “growth” 1, and it’s the longest phase of the cell cycle.
During G1, the cell mostly grows and the organelles take care of regular cellular business - like the synthesizing proteins and producing energy.
Inside the cell nucleus, there’s our DNA, organized as chromosomes - and during G1, each chromosome is made up of a single, thin spaghetti of DNA, called a chromatid.
At the end of G1, there’s a cell cycle control point called the G1 checkpoint - where the cell checks to see if the DNA is not damaged, and it synthesized the right proteins in the correct amount.
If it turns out that there is any reason for the cell not to divide - such as DNA damage, things can go one of two ways: the cell can either enter a non-dividing state, called the G0 phase, where the DNA repair mechanisms try to fix the problem, or the cell can self-destruct in a process called apoptosis.
Now, if the cell does get the go-ahead at the G1 checkpoint, it enters the S phase. S stands for “synthesis”, because during this phase, DNA is replicated, so that each daughter cell receives identical copies of the genetic material.
So for each chromosome from G1, an identical copy is created.
This happens with the help of a number of proteins, both structural proteins and enzymes, as well as energy.
Now, just to be clear - this doesn’t mean that the number of chromosomes increases - human somatic cells have 46 chromosomes throughout the cell cycle.
Summary
The cell cycle is a process that somatic cells go through that involves the duplication of DNA, growth, and division of the cell. The cell cycle can be divided into four phases: G1, S, G2, and M. G1 is the growth phase, where the cell performs all of its functions, and S is the synthesis phase, where DNA replication occurs. G2 is the growth phase, where the cell grows in size and prepares for Mitotic division, and M is the mitotic cell division phase, dividing the cell into two identical daughter cells.
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