Cell Division
I. What Is The Cell Cycle?
The cell cycle as said in my biology textbook is ''the series of events that cells go through as they grow and divide''. During the cell cyce the cell grows, prepares to divide, divides and forms 2 daughter cells and from those 2 daughter cells the cycle starts again.
The cell cycle has 4 phases; G1 phase, S phase, G2 phase and M phase. |
II. What Is Mitosis?
Cells undergo mitosis to grow and replace damaged cells. Cells sometimes divide into 2 identical cells because it needs exact copies of it (ex. hair, skin).
Cells during mitosis go through 4 different steps: prophase, metaphase, anaphase, and telophase.
The first step and longer of mitosis is prophase; prophase takes 50 or 60% of the total time to complete mitosis. Chromosomes became visible, the centrioles separate and they go to the opposite sides of the nucleus, centreoles lie in the centrosome that helps to organize the spindle, at the end of prophase the nucleus disappears, and the nuclear envelope breaks down.
Metaphase is the second phase of mitosis, the chromosomes line up across the center of the cell and chromosomes connect to a spindle fiber at its centromere.
The third step of mitosis is anaphase; the centromeres that join the sister chromatids separate, making the sister chromatids to become individual chromosomes, the chromosome continues to move until they separate in two groups near the poles of the spindle. The process ends when the chromosomes stop moving.
The final step is telophase; the chromosomes begin to dense in a tangle of material, they also lose their distinct shapes and two nuclear envelopes will form and its called cytokinesis.
Cells during mitosis go through 4 different steps: prophase, metaphase, anaphase, and telophase.
The first step and longer of mitosis is prophase; prophase takes 50 or 60% of the total time to complete mitosis. Chromosomes became visible, the centrioles separate and they go to the opposite sides of the nucleus, centreoles lie in the centrosome that helps to organize the spindle, at the end of prophase the nucleus disappears, and the nuclear envelope breaks down.
Metaphase is the second phase of mitosis, the chromosomes line up across the center of the cell and chromosomes connect to a spindle fiber at its centromere.
The third step of mitosis is anaphase; the centromeres that join the sister chromatids separate, making the sister chromatids to become individual chromosomes, the chromosome continues to move until they separate in two groups near the poles of the spindle. The process ends when the chromosomes stop moving.
The final step is telophase; the chromosomes begin to dense in a tangle of material, they also lose their distinct shapes and two nuclear envelopes will form and its called cytokinesis.
III. What Is Meiosis?
Cells undergo meiosis because cells need to reproduce more of themselves. without this process, gametes couldn't be produced and gametes cannot be made by any other cell division. The cells divide into four haploid cells because those are sex cells and are needed for reproduction. Meiosis is involved in two distinct divisions, the divisions are called meiosis I and II.
Before Meiosis I, each chromosome is replicated. Then it starts a similar process to mitosis (interphase, prophase, metaphase, anaphase, telophase and cytokinesis). However during prophase I, each chromosome pairs with its corresponding homologous to form a structure called tetrad. As homologous chromosomes form tetrads, they exchange portions of their chromatids in a process called crossing-over. After that process, the homologous chromosomes separate and two new cells are formed. The cells formed are different, they have different chromosomes and alleles.
Before Meiosis I, each chromosome is replicated. Then it starts a similar process to mitosis (interphase, prophase, metaphase, anaphase, telophase and cytokinesis). However during prophase I, each chromosome pairs with its corresponding homologous to form a structure called tetrad. As homologous chromosomes form tetrads, they exchange portions of their chromatids in a process called crossing-over. After that process, the homologous chromosomes separate and two new cells are formed. The cells formed are different, they have different chromosomes and alleles.
IV. Mitosis Vs Meiosis
Mitosis and meiosis are similar in a lot of ways. They don't have new genes combination, also they are involved in gene replication. Both have prophase, metaphase, anaphase, and telophase. In addition, both are associated with cytokinesis. Furthermore, in both cases the cell must duplicate its DNA.
Mitosis is asexual and its just the duplication of one set of chromosomes, meiosis is sexual reproduction and it involves two sets of chromosomes. Mitosis takes place all over the body, while meiosis only takes place in the sex organs and produces sex cells.
Mitosis is asexual and its just the duplication of one set of chromosomes, meiosis is sexual reproduction and it involves two sets of chromosomes. Mitosis takes place all over the body, while meiosis only takes place in the sex organs and produces sex cells.