Cell cycle (M)

In the M phase, Mitosis occurs. Mitosis is where two daughter cells are produced containing the same genetic material of the parent cell. It is divided into prophase, metaphase, anaphase and telophase.
In prophase, the spindle fibers appear and the chromosomes begin to condense into compact structures. Each chromosome has two chromatids that are held together by the centromere. It is the longest phase in Mitosis as it occupies almost half of it. This phase is related to another phase called prometaphase which is an intermediate between prophase and metaphase where the spindle fibers attach to the chromosomes as they begin to align themselves on the mid-line axis called metaphase plate. Spindle fibers bind to kinetochore regions.
In metaphase, the chromosomes finish aligning themselves on the metaphase plase.
In anaphase, the centromeres begin to divide by pulling the sister chromatids apart as they move to the opposite ends of the cells. They are capable of doing that because of the spindle fibers that are bound to the kinetochore regions. Daughter chromosomes (separated sister chromitds) are now available.
Finally, in the final stage of mitosis which is the telophase, the chromosomes uncoil, the spindle fibers disappear and the nuclear membrane is formed around the chromosomes.

QUESTIONS:

1) What is the function of centriole?

2) After which stage does the cytlokinesis occur?

REFERENCES

Britannica. (2014). Cell cycle. Retrieved February 22, 2019, from https://www.britannica.com/science/cell-cycle

Cell cycle (G1,S,G2)

During cell division, actively dividing cells pass by a stage called the cell cycle in which we have a series of diving phases that are present in the following order: two gap phases (G1 and G2),which are separated by an S phase before going to the M phase. We will consider in this post each phase briefly and then talk about the most important phase which is Mitosis in a more detailed manner which will be posted on the next post.
In the G1 phase, the cells are starting to prepare themselves for synthesis. However keep in mind that  the chromosomes are still not duplicated
In the S phase, synthesis occurs where each chromosomes consists of two sister chromatids.
In the G2 phase, the cells start to check if there are any errors in duplication that had happened in the S phase before proceeding to the M phase.

QUESTIONS: 

1) In which of these cell phases is the polymerase most active?

2) What are the different checkpoints found between these phases? 

REFERENCES: 

Editors. (2017). Cell Cycle - Definition, Phases, Examples, Regulation. Retrieved February 22,2019, from https://biologydictionary.net/cell-cycle/

Natural selection

Charles Darwin, a British naturalist, proposed the idea of natural selection. It is about evolution which states that over time we will have new species that are produced while other species can go extinct. This is due to the conditions in which these species are found where some resources that are limited will favor the survival of the ones that are the fittest. These species will be able to reproduce more efficiently then the ones less fit and will therefore leave more offspring which will lead to an increase in the frequency of the traits that are best for survival. over time species will  become adapted to their environments due to natural selection. 



QUESTIONS:

1) How much time does it take for a certain species to adapt?

2) Why do certain species adapt to the environment while others cannot?

3) Can pollution have an effect on Natural Selection?

REFERENCES: 

Britannica. (2018). Natural selection. Retrieved February 22, 2019, from https://www.britannica.com/science/natural-selection.