The four (4) major phases of Cell Division in the processes of mitosis and meiosis
While the processes of mitosis and meiosis contain a number of differences, they are also
similar in many ways. Both processes have a growth period called interphase, in which a
cell replicates its genetic material and organelles in preparation for division.
Both mitosis and meiosis involve phases: Prophase, Metaphase, Anaphase and Telophase.
Although in meiosis, a cell goes through these cell cycle phases twice. Both processes also
involve the lining up of individual duplicated chromosomes, known as sister chromatids, along
the metaphase plate. This happens in metaphase of mitosis and metaphase II of meiosis.
In addition, both mitosis and meiosis involve the separation of sister chromatids and the
formation of daughter chromosomes. This event occurs in anaphase of mitosis and anaphase
II of meiosis.
Finally, both processes end with the division of the cytoplasm that produces individual cells
Interphase
Before undergoing through the four phases, the cell first needs to grow and replicate its
chromosomes in a preliminary stage called interphase. A sex cell will only undergo
interphase once. No interphase will happen before meiosis II.
Prophase
After interphase, the cell proceeds to prophase where the nuclear membrane disintegrates and
the chromatin condenses to form the chromosomes.
The mitotic cell undergoes prophase only once.
Prophase in meiosis is relatively longer than that of mitosis. Prophase I in particular is
composed of five stages: leptotene, zygotene, pachytene, diplotene, and diakinesis.
During prophase I, homologous chromosomes form a tetrad that is composed of four chromatids.
The homologous chromosomes that make up tetrads are not genetically identical because
they came from two different parents.
Prophase II will begin without having to undergo interphase. Again, the nuclear membrane
disintegrates and the chromatin condenses.
Bouquet Stage- None. Bouquet stage is the event wherein animal and plant chromosomes
converge toward one side of the cell. This occurs during prophase I.
Crossing over –None.
Occurs during Pachytene of meiosis I. During crossing over, the chromosomes of each pair are
exchange among each other.
Metaphase
During metaphase, the chromosomes align at the equatorial plate of the cell. This event is due
to the presence of kinetochore microtubules that pull these chromosomes back and forth.
Metaphase I and II of meiosis are quite similar to mitotic metaphase. During metaphase I,
homologous chromosomes begin to align themselves at the equatorial plate as they bind to the
mitotic spindle.
During metaphase II, single chromosomes align at the equatorial plate after each cell is done
forming the spindle fibers.
Anaphase
During this stage, each (single stranded) chromosome pair is segregated toward the opposite
poles of the cell. This activity is initiated by the mitotic spindle.
During anaphase I, (double stranded) chromosomes are separated toward each cellular pole.
On the other hand, (single stranded) chromosomes are the ones being segregated during
anaphase II.
note:summarize the main points so students can read and understand
1 answer
Major Phases of Cell Division: Mitosis and Meiosis
Overview:
Both mitosis and meiosis consist of a growth period called interphase, during which the cell replicates its genetic material and prepares for division.
Mitosis involves one division cycle, while meiosis involves two.
Phases of Cell Division:
Interphase:
Cells grow and replicate chromosomes.
In meiosis, interphase occurs only once before Meiosis I; there is no interphase before Meiosis II.
Meiosis: Prophase I is longer and consists of five sub-stages (leptotene, zygotene, pachytene, diplotene, diakinesis). Homologous chromosomes pair up to form tetrads, which contain four chromatids and are genetically diverse.
Prophase II begins without interphase; similar to mitosis, the nuclear membrane disintegrates, and chromatin condenses.
Bouquet Stage: Occurs in prophase I of meiosis when chromosomes cluster at one side of the cell.
Crossing Over: Occurs during the pachytene stage of meiosis I, where homologous chromosomes exchange genetic material.
Metaphase:
Mitosis and Meiosis II: Chromosomes align at the metaphase plate, attached to spindle fibers.
Meiosis I: Homologous chromosomes align at the equatorial plate as pairs.
Anaphase:
Mitosis: Sister chromatids (single-stranded chromosomes) are pulled toward opposite poles of the cell.
Meiosis I: Homologous chromosomes (double-stranded) are separated.
Meiosis II: Sister chromatids (single-stranded) are segregated toward opposite poles.
Conclusion:
Both processes conclude with cytokinesis, resulting in the division of the cytoplasm and the formation of new cells. Mitosis results in two genetically identical cells, while meiosis produces four genetically diverse gametes.
