LS5DNARNAstructure - Lecture 5: DNA and RNA Structures 1....

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1. Nucleosides, nucleotides, and polynucleotide Lecture 5: DNA and RNA Structures 2. DNA double helix 3. Other structural properties of DNA DNA Denature and renature DNA sequence and sequence homology DNA supercoil 5’-3’ polarity Anti-parallel nature of the double strand Complementary nature of the double strand 4. RNA structure tRNA, rRNA, mRNA, hnRNA, miRNA, etc Nucleotide Structure Nucleotide Structure z The sugar in all The sugar in all nucleotides is a 5 nucleotides is a 5 carbon (pentose) carbon (pentose) sugar. sugar. z DNA and RNA each DNA and RNA each contain 4 kinds of contain 4 kinds of bases. bases. z Without a phosphate Without a phosphate this would be a this would be a nucleo nucleo side side .
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Ribose and Ribose and Deoxyribose Deoxyribose z The sugar in RNA is ribose. The sugar in RNA is ribose. z The sugar in DNA is The sugar in DNA is deoxyribose deoxyribose . z In both DNA and RNA the base is attached to In both DNA and RNA the base is attached to the 1 the 1 ’ carbon. carbon. Fig. 2-14 The Bases in The Bases in DNA and RNA DNA and RNA z DNA contains the four DNA contains the four bases A,G,C & T z RNA contains the four RNA contains the four bases A,G,C & U z In nucleotides the Nitrogen atom shown Nitrogen atom shown in in RED RED is bonded to is bonded to the 1 ’ carbon of ribose carbon of ribose (in RNA) and to the 1 (in RNA) and to the 1 carbon of deoxyribose (in DNA) (in DNA) PURINES PYRIMIDINES Adenine (A) Uracil (U) Guanine (G) Thymine (T) Cytosine (C)
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Structure of ATP Phosphoanhydride bonds
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Formation of the phosphodiester bond by a condensation reaction, in which one H 2 O is removed C A H H H 2 O enzyme z A DNA A DNA /RNA strand is a linear polymer of polymer of mononucleotides mononucleotides joined by joined by phosphodiester phosphodiester bonds between the 3 bonds between the 3 ’ carbon carbon of one nucleotide and the 5 of one nucleotide and the 5 carbon of the next carbon of the next nucleotide. nucleotide. z The bases are all joined to The bases are all joined to the 1 the 1 ’ carbons . carbons . z DNA/RNA’s polarity: 5’ to 3’ Polarity of a Polarity of a DNA DNA /RNA /RNA Strand Strand
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Some biochemical properties of DNA 1. Precipitated in ethanol, soluble in water 2. Negatively charged, stable in alkaline (high pH) or acid (low pH) 3. DNase (deoxyribonuclease) degrade DNA by hydrolysis of phosphodiester bonds. 4. DNA absorb UV light (260 nm) dsDNA (double strand) absorb less at 260 nm than ssDNA (single strand) 1 A 260 = 50 microgram/ml dsDNA, So, a DNA solution that absorbs 0.5 unit of 260 nm UV light (A 260 = 0.5) should contain 25 microgram/ml dsDNA 1 A 260 = 33 microgram/ml ssDNA Watson-Crick model of DNA structure 1. Rosalind Franklin and Maurice Wilkins obtained the x-ray differaction picture of the DNA 2. James Watson and Francis Crick proposed the 3-D structure of DNA molecule in 1953.
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This note was uploaded on 04/25/2010 for the course LIFE SCIEN Genetics taught by Professor Chen during the Spring '10 term at UCLA.

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LS5DNARNAstructure - Lecture 5: DNA and RNA Structures 1....

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