In prophase the nuclear envelope breaks down and the nucleolus disintegrates, then the centrosome which is known as the microtubule organising centre, copies itself and these move to opposite poles of the cell and these help to form the mitotic spindle. The chromosomes supercoil and are seen as two identical sister chromatids held together by their centromeres (GENIE, 2010). The next stage prometaphase involves the chromosomes lining up in the middle of the cell on the metaphase plate, the mitotic spindle fibres then bind to the kinetochores of the chromosomes. These are associated with the centromeres on the chromatids (GENIE, 2010). The kinetochore is the centre of the chromosome.
Comparing Mitosis and Meiosis with reference to i. Chromosomesii. Biological significance i. Chromosomes ii. Biological significance Modern cell theory states that all cells are derived from other cells. This means cells must have a way of copying themselves. This is cell division; two types of cell division are Meiosis and Mitosis.
However, in order for plant mitosis to accommodate a rigid cell wall vesicles derived from the Golgi apparatus move to the middle of the cell, coalesce, and produce a cell plate. Then, cell wall materials collect in the cell plate, which eventually fuses with the plasma membrane, forming a cell wall between the daughter cells. 3. The centrosome contains material that organizes the cell’s microtubules. The assembly of the spindle microtubules, which move the chromosomes to opposite poles of the cell during anaphase, starts at the centrosome, which is why it’s necessary for mitosis.
During this phase the DNA aka “deoxyribose nucleic acid” clone then forms chromatin. Chromatin is the mass of genetic material that forms into chromosomes. Interphase is divided into smaller parts: G1 Phase, S phase and G2 Phase. Throughout all the phases, the cells continuously develop by producing mitochondria, endoplasmic reticulum, and proteins. The actual division occurs during the S phase bur the G phases are mainly for the purpose of growing.
The microtubule spindles attach to the kinetochores in metaphase II, causing the chromosomes to line up, and at the start of anaphase II, the remaining cohesins at the centromere break down, so that the sister chromatids are able to separate and move to opposite ends of the cell. (Alberts et al., 2008.) They then undergo telophase and cytokinesis to produce four haploid cells. (Lodish et al., 2008.) Mitosis and meiosis are similar methods of cell division, as both produce daughter cells.
The cell cycle is the series of events that take place in a cell leading to its division and duplication of its dna to create two daughter cells. The cell cycle can be thought of as the life cycle of a cell. Basically, it is the series of growth and development steps a cell undergoes between its birth formation by the dividing of the mother cell, and reproduction division to take two new daughter cells. To divide, a cell must complete some important tasks, it has to grow, copy its genetic material, and physically split into daughter cells. Cells perform these tasks in a very organized, and predictable amount of steps that make up the cell cycle.
Meiotic spindle fibres at each pole of the cell attach to each of the sister chromatids. 8. Anaphase II: The sister chromatids are then pulled to opposite poles due to the action of the meiotic spindle. The separated chromatids are then individual
Instead of lining up on a metaphase, as in mitosis, chromosomes come together in pairs (2). Each chromosome in a pair is similar in structure (homologous), but would have come originally from different parents. Later in propha... ... middle of paper ... ...hese daughter chromosomes then begin to separate from each other, each moving away from the metaphase plate and toward one of the two spindle pole regions. The mechanisms that control chromosome separation clearly involve the interactions between microtubules and components in or near the kinetochore. Sometime after anaphase onset, the chromosomes have moved close to the spindle pole regions, and the spindle middle begins to clear.
Mitosis results in two diploid cells. In prophase, it is the first and longest stage, the nucleoli begins to disappear and the chromosomes begin to condense as well. Also in this stage the mitotic spindle begins to form in the cell. The second stage prometaphase, the kinetochore begins to appear on the two sister chromatids of the chromosomes and the proteins attach to them causing movement like a tug of war motion . The nuclear envelope begins to fragment in the cell as