Prior to mitosis, the chromosomes are duplicated so that each of the resulting daughter cells will be identical to the parent cell. Prophase is the first phase of mitosis, where the nucleus dissolves and the DNA condenses into chromosomes.
During S phase, the replication of the cell's genetic material, known as DNA, occurs. In eukaryotic cells, DNA is found in structures called chromosomes. Before replication, these chromosomes exist as long, thin chromatin fibers.
Chromosomes are held at the metaphase plate by the equal forces of the polar fibers pushing on the centromeres of the chromosomes. In anaphase, the paired chromosomes ( sister chromatids) separate and begin moving to opposite ends (poles) of the cell.
Mitosis, the division of the nucleus, is then followed by cytokinesis, the pinching off of the cytoplasm to form two new cells. In animal cells, a cleavage furrow, the indentation in an animal cell along which cytokinesis occurs, begins to form along the cell equator during telophase.
Metaphase leads to anaphase, during which each chromosome's sister chromatids separate and move to opposite poles of the cell.
During anaphase sister chromatids have been separated and reside at opposite poles of the cell. During telophase both sets of chromatids are surround by new nuclear membranes and chromosomes decondense into chromatin.
Anaphase. After metaphase is complete, the cell enters anaphase. During anaphase, the microtubules attached to the kinetochores contract, which pulls the sister chromatids apart and toward opposite poles of the cell (Figure 3c). At this point, each chromatid is considered a separate chromosome.
During the G2 phase, extra protein is often synthesized, and the organelles multiply until there are enough for two cells. Other cell materials such as lipids for the membrane may also be produced. With all this activity, the cell often grows substantially during G2.
Initially in G1 phase, the cell grows physically and increases the volume of both protein and organelles. In S phase, the cell copies its DNA to produce two sister chromatids and replicates its nucleosomes. Finally, G2 phase involves further cell growth and organisation of cellular contents.
1) Prophase: chromatin into chromosomes, the nuclear envelope break down, chromosomes attach to spindle fibres by their centromeres 2) Metaphase: chromosomes line up along the metaphase plate (centre of the cell) 3) Anaphase: sister chromatids are pulled to opposite poles of the cell 4) Telophase: nuclear envelope ...
Nondisjunction can occur during anaphase of mitosis, meiosis I, or meiosis II. During anaphase, sister chromatids (or homologous chromosomes for meiosis I), will separate and move to opposite poles of the cell, pulled by microtubules.
These phases are prophase, prometaphase, metaphase, anaphase, and telophase.
Prophase is the first phase of mitosis in which sister chromatids condense, the mitotic spindle begins to form, and centrosomes segregate to opposite poles. Centrosomes are the structures that coordinate the formation of microtubules, which allow cell division to proceed. During prophase , the sister chromatids condense until they are tightly packed. This makes them appear X-shaped, which is the representation of chromosomes with which most people are familiar. The centrosomes then start to organize the formation of the mitotic spindle, the bundle of spindle fibers attached at one end to the centrosome. The mitotic spindle is composed of microtubules that elongate from the centrosome and aim to reach the centromeres of a chromosome and the ends of opposing microtubules.
Interphase, the part of the cell cycle between division events, includes the G1, S, and G2 phases, during which the cell grows, replicates its DNA, and undergoes its usual functions.
During cytokinesis in plant cells, small membrane compartments called vesicles join together to form a structure called a cell plate. These vesicles then form a new cell wall between the daughter cells.
Mitosis consists of five continuous steps that involve the movement and separation of chromosomes in the cell. Prior to mitosis, the chromosomes are duplicated so that each of the resulting daughter cells will be identical to the parent cell.
In telophase, the final phase of mitosis, the mitotic spindle breaks down and the nuclear envelope forms around the chromosomes. A cleavage furrow forms along the cell equator, which pinches off the two new cells. This is known as cytokinesis.
In prometaphase the nuclear envelope begins to break down, allowing the kinetochore microtubules to attach to the centromeres via kinetochores. They tug the chromosomes to the middle of the cell. Other microtubules stretch across the middle of the cell (interpolar microtubules) or attach to the cell membrane (astral microtubules).