DNA

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(DNA RNA) 1. Deoxyribonucleic Acid
(DNA) 1.1. Primary Structure 1.2. Secondary
Structure - Double Helix 1.3. Tertiary
Structure 2. Ribonucleic Acid 2.1. Primary
structure 2.2. Secondary structure
2.3. Tertiary structure 2.4. Transcription 2.
5. Translation - protein synthesis
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DEOXYRIBONUCLEIC ACID (DNA)
Primary Structure
5' end
Sugar phosphate backbone
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DEOXYRIBONUCLEIC ACID (DNA)
Primary Structure
Building blocks - Nucleotides
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DEOXYRIBONUCLEIC ACID (DNA)
Primary Structure
Nucleotide Phosphate sugar base
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DEOXYRIBONUCLEIC ACID (DNA)
Primary Structure
Nucleosides Sugar Base
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DEOXYRIBONUCLEIC ACID (DNA)
Primary Structure
Deoxyribose
Nucleic acid bases
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DEOXYRIBONUCLEIC ACID (DNA)
Primary Structure
Adenine (A)
Cytosine (C)
Guanine (G)
Thymine (T)
Note Sugar phosphate backbone is
constant Bases attached in apparently random
order
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DEOXYRIBONUCLEIC ACID (DNA)
Secondary Structure - Double Helix

• Sugar phosphate backbone is ionised and faces
  outward (favourable interactions with water)
• Nucleic acid bases point inward and pair up A-T
  or G-C
• Purine pairs with pyrimidine - constant diameter
  to helix
• Base bairs are stacked (vdw interactions between
  pairs)
• Chains are complementary

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DEOXYRIBONUCLEIC ACID (DNA)
Secondary Structure - Double Helix
Base Pairing G-C base pairing involves 3
H-bonds A-T base pairing involves 2 H-bonds
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DEOXYRIBONUCLEIC ACID (DNA)
Secondary Structure - Double Helix
DNA Double Helix
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DEOXYRIBONUCLEIC ACID (DNA)
Secondary Structure - Double Helix
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DEOXYRIBONUCLEIC ACID (DNA)
Tertiary Structure

• Double helix coils into a 3D shape - supercoiling
• Double helix has to unravel during replication
• Unravelling leads to strain
• Relieved by enzyme catalysed cutting and repair
  of DNA chain
• Important to the activity of the quinolone and
  fluoroquinolone antibacterial agents which act as
  enzyme inhibitors

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RIBONUCLEIC ACID (RNA)
Primary structure

• Similar to DNA with the following exceptions
• Ribose is used instead of deoxyribose
• Uracil is used rather than thymine

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RIBONUCLEIC ACID (RNA)
Secondary structure

• Single stranded
• Some regions of helical secondary structure exist
  due to base pairing within the same strand (see
  t-RNA)
• Adenine pairs to uracil guanine pairs to cytosine

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RIBONUCLEIC ACID (RNA)
Tertiary structure

• Three types of RNA are involved in protein
  synthesis
• Messenger RNA (mRNA)
• Relays the code for a protein from DNA to the
  protein production site
• Transfer RNA (tRNA)
• The adapter unit linking the triplet code on
  mRNA to specific amino acids
• Ribosomal RNA (rRNA)
• Present in ribosomes (the production site for
  protein synthesis). Important both structurally
  and catalytically

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RIBONUCLEIC ACID (RNA)
3'p end
Tertiary structure
5'p end
Anticodon - the 3 bases are specific for the
attached amino acid - base pair to the
complementary triplet code on m- RNA (the
codon)
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RIBONUCLEIC ACID (RNA)
Transcription
The copying of a segment of DNA which codes for a
specific protein
DNA double helix
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RIBONUCLEIC ACID (RNA)
Translation - protein synthesis
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RIBONUCLEIC ACID (RNA)
Translation - protein synthesis
OH
GCU
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RIBONUCLEIC ACID (RNA)
Translation - protein synthesis
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RIBONUCLEIC ACID (RNA)
Translation - protein synthesis
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RIBONUCLEIC ACID (RNA)
Translation - protein synthesis
Translocation
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RIBONUCLEIC ACID (RNA)
Translation - protein synthesis
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RIBONUCLEIC ACID (RNA)
Translation - protein synthesis Overview
mRNA