lunes, 22 de noviembre de 2010

Cell structures and functions

In the nucleus can find structures as the chromosomes that usually in the form of chromatin, and composed of DNA; The nuclear membrane composed of two layers and numerous openings for nuclear traffic; the nucleolus have spherical shape and contains RNA for protein manufacture.
The cytoplasm contains with many structures as centrioles composed of nine tubes, each with three tubules, and involved in cellular division;the chloroplasts found in plant cells,and contain green chlorophyll where photosynthesis takes place; the cytoskeleton composed of microtubules that support cell and provides shape; the endoplasmic reticulum is a tubular network fused to nuclear membrane, and have two types the smooth type, lacks ribosomes and the rough type,ribosomes embedded in surface;the golgi apparatus composed of numerous layers forming a sac; the lysosome is digestive plant for proteins, lipids and carbohydrates and transports undigested material to cell membrane for removal; mitochondria is the second largest organelle and controls level of water and other materials in cell;the ribosomes are miniature protein factories, and composes 25% of cell's mass; and  finally the vacuoles contains water solution, and contractile vacuoles for water removal(in the unicellular organisms).

 

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