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     Nucleic Acids
     
     These macromolecules include the Ribonucleic Acids (RNA's) and the
     Deoxyribonucleic Acids (DNA's). They are also long chain
     macromolecules. The repeating subunits (building blocks) of these
     molecules are called "nucleotides". Nucleotides have three parts,
     a sugar (usually the six carbon sugar ribose or deoxyribose), a
     phosphate group (P04) and a base (which contains nitrogen).
     
     
     
     
     
     Basic Structure
     
     Nucleic acids form long chains by linking the phosphate groups to
     the sugars. The nitrogen bases stick out to the side. When DNA is
     formed there are two chains of nucleotides, each of which tends to
     coil around the other forming the so called "double helix".
     
     
     
     The two strands of DNA are said to form the "DNA molecule".
     
     Note: that one strand runs in one "direction" and the other strand
     runs in the opposite "direction".
     
     
     
     
     
     
     
     
     
     
     
     The DNA double helix.
     
     
     
     
     
     Deoxyribonucleic acid (DNA) is composed of deoxyribose sugar and
     four nitrogen bases, Complementary base paired, as follows;
     
     Adenine = = = Thymine
     
     Guanine = = = Cytosine
     
     
     
     
     
     
     
     
     
     RNA differs from DNA in that there is only one strand, and RNA
     uses ribose as its sugar, and RNA substitutes Uracil for Thymine.
     
     Adenine - Uracil
     
     Guanine - Cytosine
     

    http://kentsimmons.uwinnipeg.ca/cm1504/nucleicacids.htm

     
     
     Back to course outline

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※ 來源: DISP BBS (http://disp.twbbs.org)
※ 作者: ott  來自: 118.166.4.170  時間: 2010-01-13 22:08:03