What is the difference between meiosis i and ii

Related Content:. What is mitosis? What is meiosis? What is a cell? What is a stem cell? How helpful was this page? What's the main reason for your rating? Which of these best describes your occupation? What is the first part of your school's postcode? How has the site influenced you or others? Thankyou, we value your feedback! Figure 1: Overview of Meiosis. A series of prophase subphases can be identified depending on the appearance of the chromosomes.

They are leptotene, zygotene, pachytene, diplotene, diakinesis and synchronous processes. Throughout these stages, the disappearance of the nucleolus , the formation of meiotic spindle between the two centrosomes in the opposite poles of the cytoplasm , the disappearance of the nuclear envelope, and the invasion of the nucleus by the spindle microtubules take place sequentially.

During metaphase 1 , homologous chromosome pairs are arranged in the cell equator. A single kinetochore microtubule from each pole is connected with one centromere of the homologous chromosome pair. By the contractions of the kinetochore microtubules due to the generating tension, cohesion proteins at the chromosomal arms are cleaved, separating the homologous chromosomes from each other at the anaphase 1. The separated chromosomes are pulled to the opposite poles by the kinetochore microtubule contraction at the telophase 1.

After the completion of telophase 1, new nuclear envelopes are formed surrounding the chromosomes in the opposite poles. The second division of meiosis is meiosis 2 which is involved in the equal segregation and separation of bivalent chromosomes. Meiosis 2 is only physically similar to the mitosis vegetative cell division , not genetically since it produces haploid cells, which are used as gametes later, starting from diploid cells.

Meiosis 2 proceeds through four sequential phases: prophase 2, metaphase 2, anaphase 2 and telophase 2. During prophase 2 , nuclear envelop and nucleolus disappear, thickening the chromatids to form chromosomes.

A new pair of centrosomes appears in the opposite poles of the second cell equator, which is in a rotated position by 90 degrees relative to the meiosis 1 cell equator. The second spindle apparatus is formed from the two, new centrosomes. During metaphase 2 , centromeres of the individual chromosomes are attached to the two kinetochore microtubules from either side.

The chromosomes are aligned on the second cell equator. During anaphase 2 , centromeric cohesins are cleaved, segregating the two sister chromatids. During telophase 2 , separated sister chromatids, which are known as the sister chromosomes, are moved towards the opposite poles by the contractions of the kinetochore microtubules. Decondensation of chromosomes, as well as the disassembling of the spindle apparatus, mark the end of the telophase 2.

The nuclear envelopes and nucleoli are formed, following the division of the cytoplasm, which is known as the cytokinesis. Figure 2: Phases of meiosis 1 and 2. Meiosis 1: Meiosis 1 is a heterotypic division, reducing the chromosome number in the daughter cell by half, compared to the parent cell.

Moreover, meiosis II occurs in the production of gametes in sexual reproduction while mitosis occurs in asexual reproduction. Meiosis II and mitosis are two types of cell division. Meiosis I and II are the two steps of meiosis in which the number of chromosomes in the parent cell reduces by half.

During mitosis, the number of chromosomes in the parent cell remains the same in their daughter cells. What is Mitosis — Definition, Process, Importance 3. Meiosis II is the second step of the meiosis. Meiosis is the type of cell division, which occurs during the production of gametes.

The two steps of meiosis are meiosis I and II. During meiosis I, paired homologous chromosomes are separated into two daughter cells. These two daughter cells are haploid and they undergo meiosis II individually. The four steps of meiosis II are prophase 2, metaphase 2, anaphase 2, and telophase 2.