1.5.2
Nucleotides
Nucleic Acids
Nucleic Acids
Nucleic acids carry the cell's genetic code. These are the instructions for the function of the cell. Nucleic acids are important for passing on information from generation to generation.


Components of nucleic acids
Components of nucleic acids
- DNA and RNA are made of monomers called nucleotides.
- Nucleotides join together to form polynucleotides.
- Polynucleotides make up nucleic acids such as DNA or RNA.


Structure of nucleotides
Structure of nucleotides
- Each nucleotide is formed from a pentose sugar, a nitrogen-containing organic base and a phosphate group.
- A condensation reaction between two nucleotides forms a phosphodiester bond.
- These condensation reactions happen between a sugar group on one nucleotide and a phosphate group on a different nucleotide.


DNA nucleotide
DNA nucleotide
- The components of a DNA nucleotide are:
- A deoxyribose sugar.
- A phosphate group.
- An organic base - adenine (A), cytosine (C), guanine (G), thymine (T).
- The components of an RNA nucleotide are:
- A ribose sugar.
- A phosphate group.
- An organic base - adenine (A), cytosine (C), guanine (G), uracil (U).
1Biological Molecules
1.1Monomers & Polymers
1.2Carbohydrates
1.3Lipids
1.4Proteins
1.4.1The Peptide Chain
1.4.2Investigating Proteins
1.4.3Primary & Secondary Protein Structure
1.4.4Tertiary & Quaternary Protein Structure
1.4.5Enzymes
1.4.6Factors Affecting Enzyme Activity
1.4.7Enzyme-Controlled Reactions
1.4.8End of Topic Test - Lipids & Proteins
1.4.9A-A* (AO3/4) - Enzymes
1.4.10A-A* (AO3/4) - Proteins
1.4.11Diagnostic Misconceptions - Enzyme Inhibitors
1.5Nucleic Acids
1.6ATP
1.7Water
1.8Inorganic Ions
2Cells
2.1Cell Structure
2.2Mitosis & Cancer
2.3Transport Across Cell Membrane
2.4Cell Recognition & the Immune System
2.4.1Immune System
2.4.2Phagocytosis
2.4.3T Lymphocytes
2.4.4B Lymphocytes
2.4.5Antibodies
2.4.6Primary & Secondary Response
2.4.7Vaccines
2.4.8HIV
2.4.9Ethical Issues
2.4.10End of Topic Test - Immune System
2.4.11Exam-Style Question - Immune System
2.4.12A-A* (AO3/4) - Immune System
2.4.13Diagnostic Misconceptions - Humoral vs Cellular
3Substance Exchange
3.1Surface Area to Volume Ratio
3.2Gas Exchange
3.3Digestion & Absorption
3.4Mass Transport
3.4.1Haemoglobin
3.4.2Oxygen Transport
3.4.3The Circulatory System
3.4.4The Heart
3.4.5Blood Vessels
3.4.6Cardiovascular Disease
3.4.7Heart Dissection
3.4.8Xylem
3.4.9Phloem
3.4.10Investigating Plant Transport
3.4.11End of Topic Test - Mass Transport
3.4.12A-A* (AO3/4) - Mass Transport
3.4.13Diagnostic Misconceptions - Concentration Gradient
3.4.14Diagnostic Misconceptions - Cardiac Cycle
3.4.15Diagnostic Misconceptions - Carrying Capacity
3.4.16Diagnostic Misconceptions - Translocation
4Genetic Information & Variation
4.1DNA, Genes & Chromosomes
4.2DNA & Protein Synthesis
4.3Mutations & Meiosis
4.4Genetic Diversity & Adaptation
4.5Species & Taxonomy
4.6Biodiversity Within a Community
4.7Investigating Diversity
5Energy Transfers (A2 only)
5.1Photosynthesis
5.1.1Overview of Photosynthesis
5.1.2Photoionisation of Chlorophyll
5.1.3Production of ATP & Reduced NADP
5.1.4Cyclic Photophosphorylation
5.1.5Light-Independent Reaction
5.1.6A-A* (AO3/4) - Photosynthesis Reactions
5.1.7Limiting Factors
5.1.8Photosynthesis Experiments
5.1.9End of Topic Test - Photosynthesis
5.1.10A-A* (AO3/4) - Photosynthesis
5.2Respiration
5.2.1Overview of Respiration
5.2.2Anaerobic Respiration
5.2.3A-A* (AO3/4) - Anaerobic Respiration
5.2.4The Link Reaction
5.2.5The Krebs Cycle
5.2.6Oxidative Phosphorylation
5.2.7Respiration Experiments
5.2.8End of Topic Test - Respiration
5.2.9A-A* (AO3/4) - Respiration
5.2.10Diagnostic Misconceptions - Aerobic vs Anaerobic
5.3Energy & Ecosystems
6Responding to Change (A2 only)
6.1Nervous Communication
6.2Nervous Coordination
6.3Muscle Contraction
6.4Homeostasis
6.4.1Overview of Homeostasis
6.4.2Blood Glucose Concentration
6.4.3Controlling Blood Glucose Concentration
6.4.4End of Topic Test - Blood Glucose
6.4.5Primary & Secondary Messengers
6.4.6Diabetes Mellitus
6.4.7Measuring Glucose Concentration
6.4.8Osmoregulation
6.4.9Controlling Blood Water Potential
6.4.10ADH
6.4.11End of Topic Test - Diabetes & Osmoregulation
6.4.12A-A* (AO3/4) - Homeostasis
6.4.13Diagnostic Misconceptions - Effect of ADH
7Genetics & Ecosystems (A2 only)
7.1Genetics
7.2Populations
7.3Evolution
7.3.1Variation
7.3.2Natural Selection & Evolution
7.3.3End of Topic Test - Populations & Evolution
7.3.4Types of Selection
7.3.5Types of Selection Summary
7.3.6Overview of Speciation
7.3.7Causes of Speciation
7.3.8Diversity
7.3.9End of Topic Test - Selection & Speciation
7.3.10A-A* (AO3/4) - Populations & Evolution
7.3.11Diagnostic Misconceptions - Types of Speciation
8The Control of Gene Expression (A2 only)
8.1Mutation
8.2Gene Expression
8.2.1Stem Cells
8.2.2Stem Cells in Disease
8.2.3End of Topic Test - Mutation & Gene Epression
8.2.4A-A* (AO3/4) - Mutation & Stem Cells
8.2.5Regulating Transcription
8.2.6Epigenetics
8.2.7Epigenetics & Disease
8.2.8Regulating Translation
8.2.9Experimental Data
8.2.10End of Topic Test - Transcription & Translation
8.2.11Tumours
8.2.12Correlations & Causes
8.2.13Prevention & Treatment
8.2.14End of Topic Test - Cancer
8.2.15A-A* (AO3/4) - Gene Expression & Cancer
8.3Genome Projects
Jump to other topics
1Biological Molecules
1.1Monomers & Polymers
1.2Carbohydrates
1.3Lipids
1.4Proteins
1.4.1The Peptide Chain
1.4.2Investigating Proteins
1.4.3Primary & Secondary Protein Structure
1.4.4Tertiary & Quaternary Protein Structure
1.4.5Enzymes
1.4.6Factors Affecting Enzyme Activity
1.4.7Enzyme-Controlled Reactions
1.4.8End of Topic Test - Lipids & Proteins
1.4.9A-A* (AO3/4) - Enzymes
1.4.10A-A* (AO3/4) - Proteins
1.4.11Diagnostic Misconceptions - Enzyme Inhibitors
1.5Nucleic Acids
1.6ATP
1.7Water
1.8Inorganic Ions
2Cells
2.1Cell Structure
2.2Mitosis & Cancer
2.3Transport Across Cell Membrane
2.4Cell Recognition & the Immune System
2.4.1Immune System
2.4.2Phagocytosis
2.4.3T Lymphocytes
2.4.4B Lymphocytes
2.4.5Antibodies
2.4.6Primary & Secondary Response
2.4.7Vaccines
2.4.8HIV
2.4.9Ethical Issues
2.4.10End of Topic Test - Immune System
2.4.11Exam-Style Question - Immune System
2.4.12A-A* (AO3/4) - Immune System
2.4.13Diagnostic Misconceptions - Humoral vs Cellular
3Substance Exchange
3.1Surface Area to Volume Ratio
3.2Gas Exchange
3.3Digestion & Absorption
3.4Mass Transport
3.4.1Haemoglobin
3.4.2Oxygen Transport
3.4.3The Circulatory System
3.4.4The Heart
3.4.5Blood Vessels
3.4.6Cardiovascular Disease
3.4.7Heart Dissection
3.4.8Xylem
3.4.9Phloem
3.4.10Investigating Plant Transport
3.4.11End of Topic Test - Mass Transport
3.4.12A-A* (AO3/4) - Mass Transport
3.4.13Diagnostic Misconceptions - Concentration Gradient
3.4.14Diagnostic Misconceptions - Cardiac Cycle
3.4.15Diagnostic Misconceptions - Carrying Capacity
3.4.16Diagnostic Misconceptions - Translocation
4Genetic Information & Variation
4.1DNA, Genes & Chromosomes
4.2DNA & Protein Synthesis
4.3Mutations & Meiosis
4.4Genetic Diversity & Adaptation
4.5Species & Taxonomy
4.6Biodiversity Within a Community
4.7Investigating Diversity
5Energy Transfers (A2 only)
5.1Photosynthesis
5.1.1Overview of Photosynthesis
5.1.2Photoionisation of Chlorophyll
5.1.3Production of ATP & Reduced NADP
5.1.4Cyclic Photophosphorylation
5.1.5Light-Independent Reaction
5.1.6A-A* (AO3/4) - Photosynthesis Reactions
5.1.7Limiting Factors
5.1.8Photosynthesis Experiments
5.1.9End of Topic Test - Photosynthesis
5.1.10A-A* (AO3/4) - Photosynthesis
5.2Respiration
5.2.1Overview of Respiration
5.2.2Anaerobic Respiration
5.2.3A-A* (AO3/4) - Anaerobic Respiration
5.2.4The Link Reaction
5.2.5The Krebs Cycle
5.2.6Oxidative Phosphorylation
5.2.7Respiration Experiments
5.2.8End of Topic Test - Respiration
5.2.9A-A* (AO3/4) - Respiration
5.2.10Diagnostic Misconceptions - Aerobic vs Anaerobic
5.3Energy & Ecosystems
6Responding to Change (A2 only)
6.1Nervous Communication
6.2Nervous Coordination
6.3Muscle Contraction
6.4Homeostasis
6.4.1Overview of Homeostasis
6.4.2Blood Glucose Concentration
6.4.3Controlling Blood Glucose Concentration
6.4.4End of Topic Test - Blood Glucose
6.4.5Primary & Secondary Messengers
6.4.6Diabetes Mellitus
6.4.7Measuring Glucose Concentration
6.4.8Osmoregulation
6.4.9Controlling Blood Water Potential
6.4.10ADH
6.4.11End of Topic Test - Diabetes & Osmoregulation
6.4.12A-A* (AO3/4) - Homeostasis
6.4.13Diagnostic Misconceptions - Effect of ADH
7Genetics & Ecosystems (A2 only)
7.1Genetics
7.2Populations
7.3Evolution
7.3.1Variation
7.3.2Natural Selection & Evolution
7.3.3End of Topic Test - Populations & Evolution
7.3.4Types of Selection
7.3.5Types of Selection Summary
7.3.6Overview of Speciation
7.3.7Causes of Speciation
7.3.8Diversity
7.3.9End of Topic Test - Selection & Speciation
7.3.10A-A* (AO3/4) - Populations & Evolution
7.3.11Diagnostic Misconceptions - Types of Speciation
8The Control of Gene Expression (A2 only)
8.1Mutation
8.2Gene Expression
8.2.1Stem Cells
8.2.2Stem Cells in Disease
8.2.3End of Topic Test - Mutation & Gene Epression
8.2.4A-A* (AO3/4) - Mutation & Stem Cells
8.2.5Regulating Transcription
8.2.6Epigenetics
8.2.7Epigenetics & Disease
8.2.8Regulating Translation
8.2.9Experimental Data
8.2.10End of Topic Test - Transcription & Translation
8.2.11Tumours
8.2.12Correlations & Causes
8.2.13Prevention & Treatment
8.2.14End of Topic Test - Cancer
8.2.15A-A* (AO3/4) - Gene Expression & Cancer
8.3Genome Projects
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