Friday, September 13, 2019

HUMAN REPRODUCTIVE BIOLOGY QUESTION ASSIGNMENT Example | Topics and Well Written Essays - 750 words

HUMAN REPRODUCTIVE BIOLOGY QUESTION - Assignment Example Unlike meiosis which occurs in the gamete cells. The first mitotic stage is prophase. During this stage, the observable changes include the fading of the nucleolus while the chromatin material condenses together and forms the chromosomes. A chromosome is made up of two chromatids which have identical genetic material. Another significant change is the disassembling of the microtubules of the cytoskeleton. These are responsible for cell shape and motility. After this the cell moves to the next stage. Metaphase is the second stage in mitosis, during this stage, the nuclear envelope breaks making the nucleus no longer distinct. Another notable change is the elongation of spindle fibers. These elongate from the centrosomes and attach themselves to the kinetochores. After this, all the chromosomes are aligned in one plane at the center of the cell. This is due to the tension created by the spindle fibers. In anaphase, the third stage in mitosis, the spindle fibers shorten. The chromatids are pulled apart to opposite poles of the cell. In telophase, the fourth stage in mitosis, the daughter chromosomes are at the poles. The spindle fibers degenerate. Cytokinesis involves, the cleavage of a contractile ring that cleaves into the two daughter cells. After this microtubules responsible for cell shape reorganize it. Mitosis is important for growth and repair in eukaryotic organisms. The daughter cells have same number of chromosomes as their parent. It is important to note that unicellular organisms also use mitosis for reproduction. This is the type of cell division that divides the number of chromosomes by two. It occurs in gamete cells. Unlike mitosis, meiosis occurs in phase I and phase II of all the stages discussed in mitosis. The result is that the genetic material is divided by two. Prophase I: Chromosomes become visible at this time due to the condensation of the chromatin material. During the S phase, the chromatid duplicates so they are two

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