Phases of the cell cycle (article) | Khan Academy
Nov 11, two cells. The process begins with interphase and ends with cytokinesis. Illustration depicting the stages of mitosis and cell divison. Cell Theory, Form, and Function: Cell Cycle: Interphase, Mitosis, Cytokinesis. Cell Cycle: Interphase and cytokinesis. Refer to the illustration Cell cycle. Figure %: Telophase. Telophase is technically the final stage of mitosis. Its name derives from the latin word telos which means end. During this phase, the sister.
The phases of meiosis I. Homologous chromosomes pair up and exchange fragments in the process of crossing over.
The Cell Cycle, Mitosis and Meiosis
Homologue pairs line up at the metaphase plate. Homologues separate to opposite ends of the cell. Sister chromatids stay together.
- The cell cycle and mitosis
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Each chromosome still has two sister chromatids, but the chromatids of each chromosome are no longer identical to each other. When the homologous pairs line up at the metaphase plate, the orientation of each pair is random. For instance, in the diagram above, the pink version of the big chromosome and the purple version of the little chromosome happen to be positioned towards the same pole and go into the same cell. But the orientation could have equally well been flipped, so that both purple chromosomes went into the cell together.
This allows for the formation of gametes with different sets of homologues. Can you show me what you mean? Here is a diagram that illustrates the point a little more clearly: Diagram showing the relationship between chromosome configuration at meiosis I and homologue segregation to gametes. In this case, four different types of gametes may be produced, depending on whether the maternal homologues are positioned on the same side or on opposite sides of the metaphase plate.
In anaphase I, the homologues are pulled apart and move apart to opposite ends of the cell. The sister chromatids of each chromosome, however, remain attached to one another and don't come apart.
Relationships Between Mitosis in Eukaryotic Cells & Binary Fission in Prokaryotes
Topic Review on "Title": Importance of mitosis Mitosis is the process that a somatic cell divides into two daughter cells. It is an important process in normal organism development.
When mitosis is out of control, diseases such as cancer may occur. Cell structures for mitosis Mitosis requires a set of specialized cell structures.
Chromosomes are the most important part for mitosis because they are duplicated and then separated evenly into two daughter cells. On a chromosome there is a special structure called centromere, where the spindle, a structure pulling the chromosomes to two poles, attach. The spindle is formed around a cytosolic structure called centrosome, which is main driving force for chromosome separation. In diploid multicellular organisms sexual reproduction involves the fusion of two haploid gametes to produce a diploid zygote.
Mitotic divisions of the zygote and daughter cells are then responsible for the subsequent growth and development of the organism. In the adult organism, mitosis plays a role in cell replacement, wound healing and tumour formation. Mitosis, although a continuous process, is conventionally divided into five stages: The phases of mitosis Prophase Prophase occupies over half of mitosis. The nuclear membrane breaks down to form a number of small vesicles and the nucleolus disintegrates.
A structure known as the centrosome duplicates itself to form two daughter centrosomes that migrate to opposite ends of the cell. The centrosomes organise the production of microtubules that form the spindle fibres that constitute the mitotic spindle. The chromosomes condense into compact structures. Each replicated chromosome can now be seen to consist of two identical chromatids or sister chromatids held together by a structure known as the centromere. Prometaphase The chromosomes, led by their centromeres, migrate to the equatorial plane in the mid-line of the cell - at right-angles to the axis formed by the centrosomes.
Genetics - Mitosis and Meiosis
This region of the mitotic spindle is known as the metaphase plate. The spindle fibres bind to a structure associated with the centromere of each chromosome called a kinetochore. Individual spindle fibres bind to a kinetochore structure on each side of the centromere. The chromosomes continue to condense. Metaphase The chromosomes align themselves along the metaphase plate of the spindle apparatus.
Anaphase The shortest stage of mitosis. The centromeres divide, and the sister chromatids of each chromosome are pulled apart - or 'disjoin' - and move to the opposite ends of the cell, pulled by spindle fibres attached to the kinetochore regions.