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Becky Kriger

Polynucleotides - 0 views

www.3rd1000.com/...chem302v.htm

shared by Becky Kriger on 08 Dec 08 - Cached
  • A polymer of mononucleotides is called a polynucleotide. In polynucleotides, only one phosphoric acid is present on each ribose sugar so hydrolysis of polynucleotides produces equimolar solutions of nitrogenous base, ribose sugar, and phosphate. The phosphoric acid component of polynucleotides readily loses a proton and so polynucleotides are also called nucleic acids.
  • Polynucleotides, both DNA and RNA, are the information carriers of living organisms and play the central role in reproduction.
Becky Kriger

Introduction to DNA Structure - 0 views

www.blc.arizona.edu/...DNA_Tutorial.HTML

polynucleotides DNA

shared by Becky Kriger on 08 Dec 08 - Cached
  • Pyrimidine Bases Cytosine and thymine are pyrimidines. The 6 stoms (4 carbon, 2 nitrogen) are numbered 1-6. Like purines, all pyrimidine ring atoms lie in the same plane. Structure of C and T
  • DNA is a polymer. The monomer units of DNA are nucleotides, and the polymer is known as a "polynucleotide." Each nucleotide consists of a 5-carbon sugar (deoxyribose), a nitrogen containing base attached to the sugar, and a phosphate group. There are four different types of nucleotides found in DNA, differing only in the nitrogenous base.
  • Adenine and guanine are purines. Purines are the larger of the two types of bases found in DNA. Structures are shown below: Structure of A and G
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  • The 9 atoms that make up the fused rings (5 carbon, 4 nitrogen) are numbered 1-9. All ring atoms lie in the same plane.
  • The deoxyribose sugar of the DNA backbone has 5 carbons and 3 oxygens. The carbon atoms are numbered 1', 2', 3', 4', and 5' to distinguish from the numbering of the atoms of the purine and pyrmidine rings. The hydroxyl groups on the 5'- and 3'- carbons link to the phosphate groups to form the DNA backbone
  • A nucleoside is one of the four DNA bases covalently attached to the C1' position of a sugar.
  • Nucleosides differ from nucleotides in that they lack phosphate groups. The four different nucleosides of DNA are deoxyadenosine (dA), deoxyguanosine (dG), deoxycytosine (dC), and (deoxy)thymidine (dT, or T).
  • A nucleotide is a nucleoside with one or more phosphate groups covalently attached to the 3'- and/or 5'-hydroxyl group(s).
  • The DNA backbone is a polymer with an alternating sugar-phosphate sequence. The deoxyribose sugars are joined at both the 3'-hydroxyl and 5'-hydroxyl groups to phosphate groups in ester links, also known as "phosphodiester" bonds.
  • DNA is a normally double stranded macromolecule. Two polynucleotide chains, held together by weak thermodynamic forces, form a DNA molecule.
  • Two DNA strands form a helical spiral, winding around a helix axis in a right-handed spiral The two polynucleotide chains run in opposite directions The sugar-phosphate backbones of the two DNA strands wind around the helix axis like the railing of a sprial staircase The bases of the individual nucleotides are on the inside of the helix, stacked on top of each other like the steps of a spiral staircase.
  • Within the DNA double helix, A forms 2 hydrogen bonds with T on the opposite strand, and G forms 3 hyrdorgen bonds with C on the opposite strand.
Becky Kriger

Nucleotides, Polymerization of DNA - 0 views

users.rcn.com/...Nucleotides.html

polynucleotides DNA

shared by Becky Kriger on 08 Dec 08 - Cached
  • Nucleic acids are linear, unbranched polymers of nucleotides
  • Nucleotides consist of three parts:
  • two purines, called adenine (A) and guanine (G) two pyrimidines, called thymine (T) and cytosine (C) RNA contains: The same purines, adenine (A) and guanine (G). RNA also uses the pyrimidine cytosine (C), but instead of thymine, it uses the pyrimidine uracil (U).
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  • A five-carbon sugar (hence a pentose). Two kinds are found: Deoxyribose, which has a hydrogen atom attached to its #2 carbon atom (designated 2') Ribose, which has a hydroxyl group atom there
  • A nitrogen-containing ring structure called a base. The base is attached to the 1' carbon atom of the pentose. In DNA, four different bases are found:
  • The combination of a base and a pentose is called a nucleoside.
  • One (as shown in the first figure), two, or three phosphate groups. These are attached to the 5' carbon atom of the pentose.
  • The nucleic acids, both DNA and RNA, consist of polymers of nucleotides. The nucleotides are linked covalently between the 3' carbon atom of the pentose and the phosphate group attached to the 5' carbon of the adjacent pentose.
  • Most intact DNA molecules are made up of two strands of polymer, forming a "double helix". RNA molecules, while single-stranded, usually contain regions where two portions of the strand twist around each other to form helical regions.
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