Cell Cycle
The Cell Cycle
The cell cycle can be broken down into several phases. This includes what we call "Interphase" and "Mitosis otherwise known as "M phase". Following M phase we reach, cytokinesis which is the splitting of the two cells formed during telophase. This cycle is how our cells (primarily talking about diploid, we will cover meiosis later), are able replicate, duplicate, and synthesize growth.
Interphase
The interphase can be broken into three subsequent stages. First we have the G1 stage (not hard to remember), which stands for "growth" implying the G acronym. In this phase the cycle checks for growth factors, and cell damage. In the second phase "S phase" synthesis occurs implying the "S' acronym. In S phase is the duplication of chromosomes. In G2 stage, growth is continued, cells are checked for cell damage, and becoming ready for mitosis.
Mitosis
M phase can be broken down into a serious of four (or five) different steps). First prophase, prometaphase, metaphase, anaphase, and lastly telophase. An easy acronym to remember would be PMAT. Although prometaphase is a phase, depending on your biology course it may be not required to memorize. In spite of this prometaphase being an intermediate phase, and knowing that during this phase nuclear envelop fragments is more than enough.
Prophase (P)
In prophase, the chromatin inside the cell condenses, with the nucleoli disappearing. Following this duplicated chromosomes appear as sister chromatids and the mitotic spindle begins to form. Subsequently centromeres begin to move away from each other.
Prometaphase (Intermediate step)
As mentioned earlier, this is an intermediate step of mitosis, where the nuclear envelope begins to fragments, with microtubules entering the nuclear area and some attach to kinetochores.
Metaphase (M)
During metaphase first thought that comes to mind should be "Middle". Implying the "M" in metaphase when hearing this phrase think about the centromeres lining up at the "metaphase plate". This is a vertical or horizontal equator line running through the cell. Simultaneously centromeres begin to line up at opposite poles, with microtubules attaching to each kinetochore. This allows the cycle to segway into anaphase.
Anaphase (A)
Similarily to metaphase, when hearing the phrase "anaphase" think of pulling "away". Sister chromatids seperate and move to opposite ends of the cells via microtubules attached to each kinetochore. This is more specifically done through the process of microtubules shortening. This allows for the cell to elongate.
Telophase (T)
Telophase is the final stage of mitosis, and subsequently occurs with Cytokinesis. This is where two daughter nuclei form, with nucleoli reappear and chromosomes becoming less condensed.
Cytokinesis
Cytokinesis occurs differently dependent on the type of cell. In animal cells a cleavage furrow appears due to a contractile ring of actin filaments. Contrastly in plant cells, vesicles are produced by the Golgi travel to the middle of the cell and form a cell plate.
Real World Applications - Cancer
The cell cycle being regulated by cyclins, and cyclin dependent kinases (CDKs) is important for the regulation of the cycle. With cancer cells duplicating infinitely, and skipping all checkpoints instilled in G0, G1, and G2 checkpoints of the cell cycle this can cause tumors to form. Primarily malignent tumors which can spread throughout other cells in our body. Cancer cells will lead to a buildup and we mentioned more in depth about cancer cells in our previous topic "Cancer Cells". Read more about it if interested!
