DNA

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DNA
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STRUCTURE OF DNA

• DEOXYRIBONUCLEIC ACID
• COMPOSED OF THOUSANDS OF SMALLER UNITS CALLED
  NUCLEOTIDES
• CHROMOSOMES COMPOSED OF DNA PROTEIN

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NUCLEOTIDE

• CONSISTS OF THREE PARTS
• 1. 5 CARBON SUGAR - DEOXYRIBOSE
• 2. PHOSPHATE GROUP
• 3. NITROGEN BASE ( 1 0F 4)
• ADENINE, THYMINE,
• GUANINE, CYTOSINE

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WATSON CRICK MODEL

• 1953 ARRANGEMENT OF NUCLEOTIDES WAS DESCRIBED
  BY WATSON CRICK.
• BASED ON X-RAY DIFFRACTION DATA SUPPLIED BY
  MAURICE WILKINS ROSALIND FRANKLIN
• RECEIVED THE NOBEL PRIZE IN 1962

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CHARACTERISTICS OF DNA MOLECULE ACCORDING TO
WATSON CRICK

• LADDER TYPE ORGANIZATION
• TWISTED IN A DOUBLE SPIRAL (HELIX)
• UPRIGHT PARTS OF LADDER ARE MADE OF DEOXYRIBOSE
  SUGAR (S) PHOSPHATE (P)
• RUNGS ARE PAIRED NITROGEN BASES
• 
  

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• BASES ALWAYS PAIRED AS FOLLOWS
• ADENINE THYMINE
• GUANINE CYTOSINE
• 
  
• THERE IS A RELATIVELY WEAK HYDROGEN BOND BETWEEN
  THESE BASES