Cell Division
- The cell cycle : sequence of events by which cells grow and reproduce. In most cases, when cell reproduces it produces two genetically identical cells called daughter cells. There is the risk that sometimes cells reproduce too fast and as result they produce a tumor (cancer). In eukaryotic cells, the cell cycle goes through four phases: Gap 1 phase (G 1), Synthesis phase (S), and Gap 2 phase (G 2), Mitosis phase (M).
- G1: growth of the cell and the cell is at its smallest shape
- S: phase in which the replication of the DNA occurs (chromosomes)
- G2: in this phase the cell grows and prepares for mitosis
- Mitosis: it occurs once the DNA has replicated. It is during this phase that chromosomes separate and move to opposite poles of the cells to provide the same genetic material to each location. Once the chromosomes are in opposite poles, the cell divides to form the genetically identical daughter cells.
Mitosis involves for phases:
1. Prophase: in this phase, the chromatin condenses transform into a chromosome and these begin to move to the center of the cell. The nuclear envelope disintegrate, the nucleoli disappears and spindle fibers form at opposite sides of the cells.
2. Metaphase: The nuclear membrane completely disappears and chromosomes are completely moved to the middle or equator of the cell. This happens due to the action of the spindle which is made of microtubules.
3. Anaphase: it is in this stage that sister chromatids or pair chromosomes separate and start to move to each pole of the cells. This happens due to the shortening of the microtubules and at the end of the phase each pole has an identical set of chromosomes.
4. Telophase: Once the chromosomes are at each pole, the nuclear membrane starts to re-form, the nucleoli re-appears and the chromosomes start to form chromatin by elongating. The spindle fiber disappear and cell is elongated to prepare for cytokinesis.
Mitosis involves for phases:
1. Prophase: in this phase, the chromatin condenses transform into a chromosome and these begin to move to the center of the cell. The nuclear envelope disintegrate, the nucleoli disappears and spindle fibers form at opposite sides of the cells.
2. Metaphase: The nuclear membrane completely disappears and chromosomes are completely moved to the middle or equator of the cell. This happens due to the action of the spindle which is made of microtubules.
3. Anaphase: it is in this stage that sister chromatids or pair chromosomes separate and start to move to each pole of the cells. This happens due to the shortening of the microtubules and at the end of the phase each pole has an identical set of chromosomes.
4. Telophase: Once the chromosomes are at each pole, the nuclear membrane starts to re-form, the nucleoli re-appears and the chromosomes start to form chromatin by elongating. The spindle fiber disappear and cell is elongated to prepare for cytokinesis.
- Cytokinesis: once the nuclear division occurs, the cell undergoes the process of cytokinesis which consists of the division of the cytoplasm to form the two daughter cells. Afterwards, the cell cycle repeats itself.
Applications and skills:
It could be said that many of the present discoveries are a result of luck, but due to today's advancement in technology, it is most probable that discoveries are a result of intuition.
- Application: The correlation between smoking and incidence of cancers.
- Skill: Identification of phases of mitosis in cells viewed with a microscope or in a micrograph.
- Skill: Determination of a mitotic index from a micrograph.
- A number of scientific discoveries are claimed to be incidental or serendipitous. To what extent might some of these scientific discoveries be the result of intuition rather than luck?
It could be said that many of the present discoveries are a result of luck, but due to today's advancement in technology, it is most probable that discoveries are a result of intuition.