Eucaryotic cell structure , Biology

Eucaryotic cell structure

All eucaryotic cells have a cytoskeleton made up of a network of protein filaments (Figure shown below). This network gives the cell its shape, capacity to move and ability to transport organelles from one part of a cell to another. These protein filaments are similar in all eucaryotes. The important protein filaments are-actin and myosin in muscles and tubulin in microtubules. Actin and myosin are involved in muscle contraction and in the formation of microfilaments. Microtubules are hollow ~d form cilia, flagella, centriole and mitotic spindle. This kind of cytoskeleton is absent in the procaryotes.

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In procaryotes the DNA molecule lies freely in the cytoplasm attached to the cell membrane. In eucaryotes it is enclosed inside the nucleus. This kind of formation of compartment protects DNA from many chemical changes that occur in the cytoplasm.

The DNA found in eucaryote is not only large (human cells contain DNA thousand times larger than that in a typical bacteria) but is also packed together with histones into / chromosomes. Histones are the proteins which are basic in nature, found in eucaryotes/They bind to DNA and wrap it up into compact chromosomes. Histones also-control the expression of the characters called gene expression. Histones are important proteins which have nbt undergone any change during evolution and are identical in all plant and animal cells studied so far. Division of the nucleus by mitosis is another characteristic of the eucaryotes which permits proper and equal distribution of the genetic material to the daugher cells. Ribosomes which are the granular structures consisting of RNA and proteins are necessary for protein synthesis. These are the only organelles that are common to both procaryotes and eucaryotes. However, there are some minor differences between procaryotic and eucaryotic ribosomes.

Posted Date: 12/9/2012 11:58:14 PM | Location : United States







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