In the plant cells, a cell plate forms along the equator of the parent cell. Then, a new plasma membrane and cell wall form along each side of the cell plate.
Divide and Split Can you guess what this colorful image represents? You can see chromosomes in blue and spindles in green. After DNA replicates, it forms X-shaped chromosomes like the one shown here. Chromatid, 2. Centromere, 3. Centromere contains proteins called kinetochores not shown where spindles attach during mitosis. Metaphase During metaphase , spindle fibers fully attach to the centromere of each pair of sister chromatids. The blue lines are spindles, and the orange rectangles at the cell poles are centrioles.
Some spindles from the opposing centrioles attach with each other, and some spindles attach to the kinetochores of the sister chromosomes from their respective sides. Each chromosome is attached to two spindles. Anaphase During anaphase , sister chromatids separate and the centromeres divide. The newly separated sister chromatids are called chromosomes now. Telophase The chromosomes reach the opposite poles and begin to decondense unravel , relaxing once again into a stretched-out chromatin configuration.
Cytokinesis Cytokinesis is the final stage of cell division in eukaryotes as well as prokaryotes. It occurs differently in animal left and plant right cells. During prometaphase , the nuclear envelope is fully broken down and chromosomes are attached to microtubules from both poles of the mitotic spindle, which begin to move them toward the middle of the cell. Figure 3. Once a mitotic fiber attaches to a chromosome, the chromosome will be oriented until the kinetochores of sister chromatids face the opposite poles.
Eventually, all the sister chromatids will be attached via their kinetochores to microtubules from opposing poles. During metaphase , all the chromosomes are aligned in a plane called the metaphase plate , or the equatorial plane, midway between the two poles of the cell. At this time, the chromosomes are maximally condensed. During anaphase , the sister chromatids separate at the centromere. Each chromatid, now called a chromosome, is pulled rapidly toward the centrosome to which its microtubule is attached.
The cell becomes visibly elongated oval shaped as the polar microtubules slide against each other at the metaphase plate where they overlap. During telophase , the chromosomes reach the opposite poles and begin to decondense unravel , relaxing into a chromatin configuration.
Nuclear envelopes form around the chromosomes, and nucleosomes appear within the nuclear area. The activity below will walk you through mitosis—providing you with the chance to review the different steps of the process and how they work together. Click here for a text-only version of the activity. Cytokinesis is the second main stage of the mitotic phase during which cell division is completed via the physical separation of the cytoplasmic components into two daughter cells.
Division is not complete until the cell components have been apportioned and completely separated into the two daughter cells. Although the stages of mitosis are similar for most eukaryotes, the process of cytokinesis is quite different for eukaryotes that have cell walls, such as plant cells.
In cells such as animal cells that lack cell walls, cytokinesis follows the onset of anaphase. A contractile ring composed of actin filaments forms just inside the plasma membrane at the former metaphase plate.
The actin filaments pull the equator of the cell inward, forming a fissure. The kinetics of isthmal cells in mouse antrum were examined in three ways: the duration of cell cycle and DNA-synthesizing S stage was measured by the 'fraction of labelled mitoses' method; the duration of interphase and mitotic phases was determined from how frequently they occurred; and mice were killed at various intervals after an intravenous injection of 3H-thymidine to time the acquisition of label by the various phases of mitosis.
The duration of the isthmal cell cycle was found to be Estimates for the duration of the G1 and G2 stages were 6. At the end of meiosis, four haploid cells have been produced, but the cells are not yet gametes. The cells need to develop before they become mature gametes capable of fertilization. Just one egg is produced from the four haploid cells that result from meiosis.
The haploid cells produced by meiosis are germ cells, also known as gametes, sex cells or spores in plants and fungi. These are essential for sexual reproduction: two germ cells combine to form a diploid zygote, which grows to form another functional adult of the same species. During meiosis II, the sister chromatids within the two daughter cells separate, forming four new haploid gametes.
The mechanics of meiosis II is similar to mitosis, except that each dividing cell has only one set of homologous chromosomes. Begin typing your search term above and press enter to search. Press ESC to cancel.
Skip to content Home Sociology Which phase of mitosis is the longest and why? Ben Davis October 22, Which phase of mitosis is the longest and why? Why is Interphase the longest phase? Why is G1 longest? Why does prophase take the longest in mitosis?
Which is the shortest stage of mitosis? Which phase of mitosis is most common? Why is cytokinesis the shortest phase? What phase do cells spend the least time in?
What phase do cells spend the most time in? Which cell type divides at the highest rate? What phase does the cell grow?
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