Lecture #6 - Nucleic Acids

Ogan Gurel, MD Biology 301 Lecture #6 Roosevelt University

Biology 301 Cellular and Molecular Biology Spring 2002

Lecture # 6: Nucleic Acids

Ogan Gurel, MD Biology 301 Lecture #6 Roosevelt University

Overall outline  The Central Dogma  Nucleotide Chemistry  Nucleic Acid Structure  Nucleic Acid Function

Ogan Gurel, MD Biology 301 Lecture #6 Roosevelt University

The Central Dogma  Information Flow in the Cell

Information Flow in the Cell

Ogan Gurel, MD Biology 301 Lecture #6 Roosevelt University

Ogan Gurel, MD Biology 301 Lecture #6 Roosevelt University

Nucleotide Chemistry  Synthesis of Polymers  Breakdown of Polymers  Phosphoanhydrides & Phosphoesters  Chemistry of Phospho-derivatives  The structures of nucleotides and polynucleotides

Synthesis of Polymers

Ogan Gurel, MD Biology 301 Lecture #6 Roosevelt University

Breakdown of Polymers

Ogan Gurel, MD Biology 301 Lecture #6 Roosevelt University

Phosphoanhydrides & Phosphoesters Phosphoanhydrides are common in ATP and other “high-energy compounds.” Phosphodiesters compose the backbone of DNA and RNA.

Ogan Gurel, MD Biology 301 Lecture #6 Roosevelt University

Chemistry of Phosphoderivatives  Adenosine triphosphate (ATP) is a phosphoanhydride composed of an adenine base, a ribose sugar and a triphosphate group.  Phosphoanhydrides are “High-energy” compounds. High-energy is not an intrinsic property of the bond per se, but rather a relative energy between the phosphoanhydride and its highly stable hydrolysis products.

Ogan Gurel, MD Biology 301 Lecture #6 Roosevelt University

The structures of nucleotides and polynucleotides

Ogan Gurel, MD Biology 301 Lecture #6 Roosevelt University

Ogan Gurel, MD Biology 301 Lecture #6 Roosevelt University

Nucleic Acid Structure  The Double Helix  Structure Determination  DNA Structure  Chromatin Structure

The Double Helix

Ogan Gurel, MD Biology 301 Lecture #6 Roosevelt University

Structure Determination

Ogan Gurel, MD Biology 301 Lecture #6 Roosevelt University

Ogan Gurel, MD Biology 301 Lecture #6 Roosevelt University

DNA Structure DOUBLE HELIX  H

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H

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{

1.  X­ray fiber diffraction 

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2.  Structure of nucleotides 

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3.  Chargaff’ s   R u l e s   ( G = C ,   A = T )   O

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CH2

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Base

Base

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{

H

H

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H

H O O

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H CH2

H CH2

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H

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Base

Base

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H H

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H CH2

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H O

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  4.  Suggested possible mechanism for REPLICATION   

  Proteins  usually  have  a  hydrophobic  interior  and  a  hydrophilic  exterior.    Describe  how  this  paradigm also applies to DNA. 

Chromatin Structure  CHROMATIN = DNA + PROTEIN (histones)  Chromatin is involved in the packaging and regulation of DNA and is organized in a hierarchical fashion of successive DNA packing arrangements.

Ogan Gurel, MD Biology 301 Lecture #6 Roosevelt University

Ogan Gurel, MD Biology 301 Lecture #6 Roosevelt University

Nucleic Acid Function  DNA > RNA > Protein

DNA > RNA > Protein

Ogan Gurel, MD Biology 301 Lecture #6 Roosevelt University