3.8.6

DNA

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DNA

DNA is essential to pass on genetic information in living organisms. It provides the necessary code in cell replication and protein synthesis.

Basic structure of DNA

Basic structure of DNA

A strand of DNA is a polymer of nucleotides - in other words, a chain of nucleotides.
Nucleotides are made up of a deoxyribose sugar molecule attached to a phosphate ion (PO₄³⁻) and a complementary base pair - as shown above.
Nucleotides join together to produce a chain by a condensation reaction between a phosphate and a deoxyribose molecule.

Basic structure of DNA

Basic structure of DNA

There are four possible bases:
- Adenine (A).
- Thymine (T).
- Guanine (G).
- Cytosine (C).

Double helix in DNA

Double helix in DNA

DNA has a double helix structure constructed from two antiparallel nucleotide chains.
The double helix is held together by hydrogen bonding between complementary base pairs:
- A with T and vice versa.
- C with G and vice versa.

Base pairing

Base pairing

Above shows how the two complementary base pairs couple together through hydrogen bonding.
- C-G form THREE hydrogen bonds.
- A-T form TWO hydrogen bonds.
The double helix structures itself based around these hydrogen bonds.
- It twists and turns until the hydrogen bonds are in the correct placement (correct alignment and distance between the two bases).

DNA replication

DNA replication

DNA replication and protein synthesis rely on the breaking and reforming of hydrogen bonds between strands.
In DNA replication, the strands separate and new strands are constructed anti-parallel to the two old strands.
- Each new helix contains one new (daughter) strand and one old (parent) strand.

1

Physical Chemistry

1.1

Atoms, Molecules & Stoichiometry

1.1.1Relative Masses 1.1.2The Mole 1.1.3Mass Spectrometry 1.1.4Empirical & Molecular Formulae 1.1.5Balanced Equations 1.1.6Molar Volume 1.1.7End of Topic Test - Amount of Substance

1.2

Atomic Structure

1.2.1Fundamental Particles 1.2.2Isotopes & Mass Number 1.2.3Electron Shells, Sub-Shells & Orbitals 1.2.4Electron Configuration 1.2.5Ionisation Energy 1.2.6Factors Affecting Ionisation Energies 1.2.7Trends of Ionisation 1.2.8Specific Impacts on Ionisation Energies 1.2.9Electron Affinity 1.2.10End of Topic Test - Atomic Structure 1.2.11A-A* (AO2/3) - Atomic Structure

1.3

Chemical Bonding

1.3.1Ionic Bonding 1.3.2Covalent & Dative Bonding 1.3.3Shapes of Molecules 1.3.4Intermolecular Forces 1.3.5Intermolecular Forces 2 1.3.6Electronegativity 1.3.7Bond Length, Bond Energy, & Bond Polarity 1.3.8Metallic Bonding 1.3.9Physical Properties 1.3.10End of Topic Test - Bonding 1.3.11A-A* (AO2/3) - Bonding

1.4

States of Matter

1.4.1Simple Covalent Molecules 1.4.2The Ideal Gas Equation 1.4.3States of Matter 1.4.4Particle Diagrams 1.4.5The Liquid State 1.4.6Giant Ionic Lattices 1.4.7Giant Metallic Lattices 1.4.8Giant Covalent Structures 1.4.9Graphene & Fullerene 1.4.10Recycling

1.5

Chemical Energetics

1.5.1Calorimetry 1.5.2Bond Enthalpies 1.5.3Enthalpy Changes 1.5.4Hess' Law 1.5.5Born-Haber Cycles 1.5.6Born-Haber Cycle Calculations 1.5.7Entropy 1.5.8Free Energy 1.5.9End of Topic Test - Energetics

1.6

Electrochemistry

1.6.1Electrochemical Cells 1.6.2Electrochemical Series 1.6.3Commercial Application 1.6.4Nernst Equation 1.6.5Redox

1.7

Equilibria

1.7.1Dynamic Equilibrium & Le Chatelier 1.7.2Kc 1.7.3Kp 1.7.4pH 1.7.5The Ionic Product of Water 1.7.6Weak Acids & Bases 1.7.7Introduction to Solubility Equilibria 1.7.8Solubility Equilibria Calculations 1.7.9Free Energy of Dissolution 1.7.10pH and Solubility 1.7.11Common-Ion Effect 1.7.12End of Topic Test - Kp & Electrochemistry 1.7.13A-A* (AO2/3) - Electrochemical Cells

1.8

Partition Coefficient

1.9

Reaction Kinetics

1.9.1Collision Theory 1.9.2Orders, Rate Constants & Equations 1.9.3Rate Graphs 1.9.4Rate Determining Step 1.9.5Maxwell-Boltzmann Distribution 1.9.6Catalysts 1.9.7Homogeneous Catalysts 1.9.8Heterogeneous Catalysts 1.9.9End of Topic Test - Kinetics 1.9.10End of Topic Test - Rate Equations 1.9.11A-A* (AO2/3) - Rate Equations

2

Inorganic Chemistry

2.1

The Periodic Table

2.1.1The Periodic Table 2.1.2Trends in the Periodic Table 2.1.3End of Topic Test - Periodicity & Trends 2.1.4Ceramics 2.1.5Period 3 Elements & Oxides 2.1.6Period 3 Oxides 2.1.7End of Topic Test - Period 3

2.2

Group 2

2.2.1Group 2 Chemistry

2.3

Group 17

2.3.1Introduction to Halogens 2.3.2Reactions of Halogens 2.3.3Chlorine & Chlorate(I)2.3.4End of Topic Test - Group 17 2.3.5A-A* (AO2/3) - Periodicity, Group 2 & 17

2.4

Transition Metals

2.4.1General Properties 2.4.2Titrations 2.4.3Shapes of Complex Ions 2.4.4Variable Oxidation States 2.4.5Ligands 2.4.6Colours of Ions 2.4.7Stereoisomerism of Complex Ions 2.4.8Cisplatin 2.4.9Ligand Substitutions & Kstab 2.4.10End of Topic Test - Transition Metals 2.4.11A-A* (AO2/3) - Transition Metals

2.5

Nitrogen & Sulfur

2.5.1Nitrogen & Ammonia 2.5.2Formulated vs Manure Fertilisers 2.5.3Nitrogen Containing Fertilisers 2.5.4Fertilizers & Eutrophication 2.5.5Common Atmospheric Pollutants & Their Properties 2.5.6Catalytic Converters 2.5.7Atmospheric Oxides

3

Organic Chemistry & Analysis

3.1

Introduction to Organic Chemistry

3.1.1Naming Conventions 3.1.2Mechanism 3.1.3Isomerism 3.1.4End of Topic Test - Introduction to Organic Chem

3.2

Hydrocarbons

3.2.1Fractional Distillation 3.2.2Cracking 3.2.3Combustion 3.2.4Chlorination 3.2.5End of Topic Test - Alkanes 3.2.6Introduction to Alkenes 3.2.7Reactions of Alkenes 3.2.8Polymerisation Reactions 3.2.9End of Topic Test - Alkenes 3.2.10Arenes 3.2.11Evidence for Structure of Arenes 3.2.12Reactions of Benzene 3.2.13End of Topic Test -Arenes

3.3

Halogen Derivatives

3.3.1Properties of Haloalkanes 3.3.2Substitution Reactions of Haloalkanes 3.3.3Environmental Impacts of Haloalkanes 3.3.4End of Topic Test - Halogenoalkanes

3.4

Hydroxy Compounds

3.4.1Types of Alcohol 3.4.2Oxidation 1 3.4.3Oxidation 2 3.4.4Elimination 3.4.5Acids & Esters 3.4.6Acyl Chlorides & Acylation 3.4.7Phenols & Their Reactions 3.4.8End of Topic Test - Alcohols

3.5

Carbonyl Compounds

3.5.1Carbonyls 3.5.2Hydrogen Bonding & Carbonyls 3.5.3Aldehydes & Ketones 3.5.4Tri-Iodomethane Reaction 3.5.5End of Topic Test -Carbonyls

3.6

Carboxylic Acids & Derivatives

3.6.1Properties of Carboxylic Acids 3.6.2Esters 3.6.3Acyl Chlorides 3.6.4End of Topic Test - Carboxylic Acids

3.7

Nitrogen Compounds

3.7.1Nature & Preparation of Amines 3.7.2Basicity & Nucleophilicity 3.7.3Amides 3.7.4Reactions of Amino Acids 3.7.5Amino Acids

3.8

Polymerisation

3.8.1Properties of Addition Polymers 3.8.2Condensation Polymerisation 3.8.3Effects of Side-Chains on Polymers 3.8.4Hydrolysis of Ester & Amide Groups 3.8.5Proteins 3.8.6DNA 3.8.7Adhesive & Conducting Polymers 3.8.8End of Topic Test - Amines & Proteins

3.9

Analytical Techniques

3.9.1Chromatography 3.9.2High-Performance Liquid Chromatography 3.9.3Gas Chromatography 3.9.4IR Spectroscopy 3.9.5Uses of IR Spectroscopy 3.9.6Mass Spectrometry 3.9.7Mass Spectrometry Analysis 3.9.8Nuclear Magnetic Resonance 3.9.9Carbon-13 NMR 3.9.10Proton NMR I 3.9.11Proton NMR II 3.9.12End of Topic Test - Analytical Techniques 3.9.13A-A* (AO2/3) - Analytical Techniques

3.10

Organic Synthesis

3.10.1Chirality & Drug Synthesis 3.10.2Organic Synthesis 3.10.3Examples of Synthetic Routes 3.10.4End of Topic Test - Organic Synthesis

Jump to other topics

1

Physical Chemistry

1.1

Atoms, Molecules & Stoichiometry

1.1.1Relative Masses 1.1.2The Mole 1.1.3Mass Spectrometry 1.1.4Empirical & Molecular Formulae 1.1.5Balanced Equations 1.1.6Molar Volume 1.1.7End of Topic Test - Amount of Substance

1.2

Atomic Structure

1.2.1Fundamental Particles 1.2.2Isotopes & Mass Number 1.2.3Electron Shells, Sub-Shells & Orbitals 1.2.4Electron Configuration 1.2.5Ionisation Energy 1.2.6Factors Affecting Ionisation Energies 1.2.7Trends of Ionisation 1.2.8Specific Impacts on Ionisation Energies 1.2.9Electron Affinity 1.2.10End of Topic Test - Atomic Structure 1.2.11A-A* (AO2/3) - Atomic Structure

1.3

Chemical Bonding

1.3.1Ionic Bonding 1.3.2Covalent & Dative Bonding 1.3.3Shapes of Molecules 1.3.4Intermolecular Forces 1.3.5Intermolecular Forces 2 1.3.6Electronegativity 1.3.7Bond Length, Bond Energy, & Bond Polarity 1.3.8Metallic Bonding 1.3.9Physical Properties 1.3.10End of Topic Test - Bonding 1.3.11A-A* (AO2/3) - Bonding

1.4

States of Matter

1.4.1Simple Covalent Molecules 1.4.2The Ideal Gas Equation 1.4.3States of Matter 1.4.4Particle Diagrams 1.4.5The Liquid State 1.4.6Giant Ionic Lattices 1.4.7Giant Metallic Lattices 1.4.8Giant Covalent Structures 1.4.9Graphene & Fullerene 1.4.10Recycling

1.5

Chemical Energetics

1.5.1Calorimetry 1.5.2Bond Enthalpies 1.5.3Enthalpy Changes 1.5.4Hess' Law 1.5.5Born-Haber Cycles 1.5.6Born-Haber Cycle Calculations 1.5.7Entropy 1.5.8Free Energy 1.5.9End of Topic Test - Energetics

1.6

Electrochemistry

1.6.1Electrochemical Cells 1.6.2Electrochemical Series 1.6.3Commercial Application 1.6.4Nernst Equation 1.6.5Redox

1.7

Equilibria

1.7.1Dynamic Equilibrium & Le Chatelier 1.7.2Kc 1.7.3Kp 1.7.4pH 1.7.5The Ionic Product of Water 1.7.6Weak Acids & Bases 1.7.7Introduction to Solubility Equilibria 1.7.8Solubility Equilibria Calculations 1.7.9Free Energy of Dissolution 1.7.10pH and Solubility 1.7.11Common-Ion Effect 1.7.12End of Topic Test - Kp & Electrochemistry 1.7.13A-A* (AO2/3) - Electrochemical Cells

1.8

Partition Coefficient

1.9

Reaction Kinetics

1.9.1Collision Theory 1.9.2Orders, Rate Constants & Equations 1.9.3Rate Graphs 1.9.4Rate Determining Step 1.9.5Maxwell-Boltzmann Distribution 1.9.6Catalysts 1.9.7Homogeneous Catalysts 1.9.8Heterogeneous Catalysts 1.9.9End of Topic Test - Kinetics 1.9.10End of Topic Test - Rate Equations 1.9.11A-A* (AO2/3) - Rate Equations

2

Inorganic Chemistry

2.1

The Periodic Table

2.1.1The Periodic Table 2.1.2Trends in the Periodic Table 2.1.3End of Topic Test - Periodicity & Trends 2.1.4Ceramics 2.1.5Period 3 Elements & Oxides 2.1.6Period 3 Oxides 2.1.7End of Topic Test - Period 3

2.2

Group 2

2.2.1Group 2 Chemistry

2.3

Group 17

2.3.1Introduction to Halogens 2.3.2Reactions of Halogens 2.3.3Chlorine & Chlorate(I)2.3.4End of Topic Test - Group 17 2.3.5A-A* (AO2/3) - Periodicity, Group 2 & 17

2.4

Transition Metals

2.4.1General Properties 2.4.2Titrations 2.4.3Shapes of Complex Ions 2.4.4Variable Oxidation States 2.4.5Ligands 2.4.6Colours of Ions 2.4.7Stereoisomerism of Complex Ions 2.4.8Cisplatin 2.4.9Ligand Substitutions & Kstab 2.4.10End of Topic Test - Transition Metals 2.4.11A-A* (AO2/3) - Transition Metals

2.5

Nitrogen & Sulfur

2.5.1Nitrogen & Ammonia 2.5.2Formulated vs Manure Fertilisers 2.5.3Nitrogen Containing Fertilisers 2.5.4Fertilizers & Eutrophication 2.5.5Common Atmospheric Pollutants & Their Properties 2.5.6Catalytic Converters 2.5.7Atmospheric Oxides

3

Organic Chemistry & Analysis

3.1

Introduction to Organic Chemistry

3.1.1Naming Conventions 3.1.2Mechanism 3.1.3Isomerism 3.1.4End of Topic Test - Introduction to Organic Chem

3.2

Hydrocarbons

3.2.1Fractional Distillation 3.2.2Cracking 3.2.3Combustion 3.2.4Chlorination 3.2.5End of Topic Test - Alkanes 3.2.6Introduction to Alkenes 3.2.7Reactions of Alkenes 3.2.8Polymerisation Reactions 3.2.9End of Topic Test - Alkenes 3.2.10Arenes 3.2.11Evidence for Structure of Arenes 3.2.12Reactions of Benzene 3.2.13End of Topic Test -Arenes

3.3

Halogen Derivatives

3.3.1Properties of Haloalkanes 3.3.2Substitution Reactions of Haloalkanes 3.3.3Environmental Impacts of Haloalkanes 3.3.4End of Topic Test - Halogenoalkanes

3.4

Hydroxy Compounds

3.4.1Types of Alcohol 3.4.2Oxidation 1 3.4.3Oxidation 2 3.4.4Elimination 3.4.5Acids & Esters 3.4.6Acyl Chlorides & Acylation 3.4.7Phenols & Their Reactions 3.4.8End of Topic Test - Alcohols

3.5

Carbonyl Compounds

3.5.1Carbonyls 3.5.2Hydrogen Bonding & Carbonyls 3.5.3Aldehydes & Ketones 3.5.4Tri-Iodomethane Reaction 3.5.5End of Topic Test -Carbonyls

3.6

Carboxylic Acids & Derivatives

3.6.1Properties of Carboxylic Acids 3.6.2Esters 3.6.3Acyl Chlorides 3.6.4End of Topic Test - Carboxylic Acids

3.7

Nitrogen Compounds

3.7.1Nature & Preparation of Amines 3.7.2Basicity & Nucleophilicity 3.7.3Amides 3.7.4Reactions of Amino Acids 3.7.5Amino Acids

3.8

Polymerisation

3.8.1Properties of Addition Polymers 3.8.2Condensation Polymerisation 3.8.3Effects of Side-Chains on Polymers 3.8.4Hydrolysis of Ester & Amide Groups 3.8.5Proteins 3.8.6DNA 3.8.7Adhesive & Conducting Polymers 3.8.8End of Topic Test - Amines & Proteins

3.9

Analytical Techniques

3.9.1Chromatography 3.9.2High-Performance Liquid Chromatography 3.9.3Gas Chromatography 3.9.4IR Spectroscopy 3.9.5Uses of IR Spectroscopy 3.9.6Mass Spectrometry 3.9.7Mass Spectrometry Analysis 3.9.8Nuclear Magnetic Resonance 3.9.9Carbon-13 NMR 3.9.10Proton NMR I 3.9.11Proton NMR II 3.9.12End of Topic Test - Analytical Techniques 3.9.13A-A* (AO2/3) - Analytical Techniques

3.10

Organic Synthesis

3.10.1Chirality & Drug Synthesis 3.10.2Organic Synthesis 3.10.3Examples of Synthetic Routes 3.10.4End of Topic Test - Organic Synthesis

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Proteins

Adhesive & Conducting Polymers