Undergraduate
  1. General chemistry  1.1. Introduction to Chemistry  1.2. Atomic Structure  1.2.1. Subatomic particles  1.2.2. Atomic Model  1.2.3. Quantum numbers  1.2.4. Electron Configuration  1.2.5. Periodic trends  1.2.6. Isotopes and their applications  1.3. Chemical bond  1.3.1. Ionic bond  1.3.2. Covalent bonds  1.3.3. Metal Bond  1.3.4. Hybridization  1.3.5. Molecular geometry and VSEPR theory  1.3.6. Bond polarity and dipole moment  1.4. Stoichiometry  1.4.1. Mole concept  1.4.2. Empirical and molecular formula  1.4.3. Limiting reactant and excess reactant  1.4.4. Percent Yield and Purity  1.4.5. Dilution calculation  1.5. States of matter  1.5.1. Gas Laws  1.5.2. Matter and Intermolecular Forces  1.5.3. Solid and Crystal Structures  1.5.4. Phase diagram  1.5.5. Plasma and supercritical fluid  1.6. Chemical reactions  1.6.1. Types of Chemical Reactions  1.6.2. Balancing Chemical Equations  1.6.3. Thermochemical reactions  1.6.4. Reaction energy profiles  1.7. Solutions and Mixtures  1.7.1. Concentration units  1.7.2. Syndrome properties  1.7.3. Solubility and Solubility Rules  1.7.4. Henry's Law and Raoult's Law  1.7.5. Partition coefficient  1.8. Chemical equilibrium  1.8.1. Law of mass action  1.8.2. Le Chatelier's principle  1.8.3. Reaction quotient  1.8.4. To use this online calculator for Equilibrium Constant, enter Equilibrium Constant (Eq.) and hit the calculate button. Here is how the Equilibrium Constant calculation can be explained with given input values -> 0.05 = 0.05/0.  1.8.5. Acid-base balance  1.9. Acids and bases  1.9.1. Arrhenius, Brønsted–Lowry, and Lewis definitions  1.9.2. pH and pOH  1.9.3. Acid-base titration  1.9.4. Buffer Solution  1.9.5. Acid-base indicator  1.9.6. Polyprotic Acids and Bases  1.10. Electrochemistry  1.10.1. redox reactions  1.10.2. Galvanic and Electrolytic Cells  1.10.3. Nernst equation  1.10.4. Electrolysis  1.10.5. Faraday's laws of electrolysis  1.11. Thermodynamics  1.11.1. Laws of Thermodynamics  1.11.2. Enthalpy, entropy and Gibbs free energy  1.11.3. Spontaneity of reactions  1.11.4. Thermodynamic cycles (Hess's law, Carnot cycle)  1.12. Kinetics  1.12.1. Rate law and reaction order  1.12.2. Activation Energy and Catalyst  1.12.3. Collision theory  1.12.4. Reaction mechanism  1.12.5. Transition state theory
  2. Organic chemistry  2.1. Structure and relationships  2.1.1. Hybridisation in Carbon Compounds  2.1.2. Resonance and aromatization  2.1.3. Molecular orbitals  2.1.4. Inductive and mesomeric effects  2.2. Hydrocarbons  2.2.1. Hydrocarbons  2.2.2. Alkene  2.2.3. Alkynes  2.2.4. Aromatic compounds  2.2.5. Cycloalkanes and Conformation  2.3. Functional Group  2.3.1. Alcohols and phenols  2.3.2. Ethers and epoxides  2.3.3. Aldehyde and ketone  2.3.4. Carboxylic acids and derivatives  2.3.5. Amin  2.3.6. Esters and amides  2.3.7. Thiols and sulfides  2.4. Stereoscopic  2.4.1. Isomerism in Stereochemistry  2.4.2. Chirality and optical activity  2.4.3. Structural analysis  2.4.4. Diastereomers and Enantiomers  2.5.1. Substitution reactions  2.5.2. Elimination reactions  2.5.3. Addition reactions  2.5.4. Radical reactions  2.5.5. Rearrangement reactions  2.5.6. Pericyclic Reactions  2.6. Spectroscopy and structural analysis  2.6.1. Infrared Spectroscopy  2.6.2. Nuclear magnetic resonance spectroscopy  2.6.3. Mass Spectrometry  2.6.4. UV-visible spectroscopy  2.6.5. X-ray crystallography  2.7. Polymer chemistry  2.7.1. Addition and Condensation Polymers  2.7.2. Polymerization mechanism  2.7.3. Biodegradable Polymer  2.7.4. Conducting and smart polymers
  3. Inorganic chemistry  3.1. Coordination chemistry  3.1.1. Ligands and coordination compounds  3.1.2. Crystal field theory  3.1.3. Molecular Orbital Theory in Coordination Compounds  3.1.4. Jahn–Taylor distortion  3.2. Main Group Chemistry  3.2.1. Alkali and alkaline earth metals  3.2.2. Halogens and Noble Gases  3.2.3. Transition metals and their complexes  3.2.4. Lanthanides and Actinides  3.3. Solid state chemistry  3.3.1. Crystal lattices and unit cells  3.3.2. Defects in solids  3.3.3. Electrical and magnetic properties  3.3.4. Superconductivity  3.4. Bio-inorganic chemistry  3.4.1. Metal ions in biology  3.4.2. Enzymatic reactions with metals  3.4.3. Metal poisoning and detoxification  3.4.4. Metalloproteins and Metalloenzymes
  4. Physical chemistry  4.1. Quantum Chemistry  4.1.1. Wave–particle duality  4.1.2. Schrödinger Equation  4.1.3. Quantum Numbers and Orbitals  4.1.4. Atomic and molecular spectroscopy  4.2. Statistical mechanics  4.2.1. Maxwell–Boltzmann distribution  4.2.2. Partitioning functions  4.2.3. Bose–Einstein and Fermi–Dirac statistics  4.3. Chemical thermodynamics  4.3.1. Gibbs Free Energy  4.3.2. Phase transition  4.3.3. Thermodynamic efficiency  4.4. Surface chemistry  4.4.1. Absorption and Catalysis  4.4.2. Colloids and Emulsions
  5. Analytical Chemistry  5.1. Classical methods  5.1.1. Gravimetric Analysis  5.1.2. titrimeter  5.2. Instrumental methods  5.2.1. Chromatography  5.2.2. Spectroscopy  5.2.3. Electroanalytical methods  5.2.4. X-ray diffraction
  6. Industrial Chemistry  6.1. Petrochemistry  6.2. Chemical engineering principles  6.3. Green Chemistry  6.4. Pharmaceuticals and Drug Synthesis
  7. Biochemistry  7.1. Carbohydrates  7.2. Proteins and enzymes  7.3. Lipids and membranes  7.4. Nucleic acids  7.5. Metabolism and Bioenergetics  7.6. Enzyme kinetics and mechanism

Undergraduate → Biochemistry ↓


Nucleic acids


Nucleic acids are biopolymers essential for life. They are found in all living cells and viruses and serve as information stores that direct the synthesis of proteins and other important cellular components. There are two primary types of nucleic acids: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). Each plays a different, but equally important role in the storage and expression of genetic information.

Structure of nucleic acids

Nucleic acids are made up of long chains of nucleotides. A nucleotide, the basic building block, consists of a sugar molecule, a phosphate group, and a nitrogenous base. The sugar in DNA is deoxyribose, while in RNA it is ribose; this difference gives each nucleic acid its name.

Nucleotide components

  • Sugars: The backbone of nucleic acids is made up of alternating sugars and phosphate groups. In DNA, the sugar is deoxyribose, which lacks one oxygen atom compared with the ribose in RNA. This difference is important for the structural stability and function of the molecules.
  • Phosphate group: The phosphate group forms phosphodiester bonds with the 3' carbon of one sugar and the 5' carbon of the next sugar in an alternating sequence, giving DNA and RNA their direction.
  • Nitrogenous bases: DNA contains four nitrogenous bases: adenine (A), thymine (T), cytosine (C), and guanine (G). RNA contains uracil (U) instead of thymine. These bases pair specifically, forming the rungs of a nucleic acid ladder: A with T or U, and C with G.

Illustration of the sugar-phosphate base of a nucleic acid, showing structural components.

Double helix of dna

The most striking structural feature of DNA is its double-stranded helical shape, first proposed by James Watson and Francis Crick. This double helix consists of two long polynucleotide strands that coil around each other, forming nitrogenous base pairs and forming the steps of a helical ladder.

Base pairing

Base pairing is crucial to the structure of the double helix. The specific pairing (A with T and C with G) allows DNA to accurately carry genetic information. The strands are complementary, meaning that the sequence of bases on one strand determines the sequence on the other. This property is important for DNA replication and transcription.

A Tea

Illustration of the DNA double helix, emphasizing the base pairs AT and CG.

DNA functions

DNA is the primary genetic material in most organisms. Its main functions include replication, information encoding, mutation and recombination, and gene expression.

Replica

During cell division, DNA must be copied so that each new cell receives an identical copy. Complementary base pairing allows one strand to serve as a template for synthesizing the other. Enzymes such as DNA polymerase facilitate this process, and it involves unwinding the double helix, using each strand as a template to create a new complementary strand.

DNA Strand 1: 5'-ATTGCCT A-3'
DNA Strand 2: 3'-TAACGGA T-5'

Example of complementary DNA strands with directionality.

Gene expression

DNA contains instructions for making proteins. This process involves two main steps: transcription and translation. Transcription is the synthesis of RNA from a DNA template, in which the DNA sequence is copied into mRNA. The mRNA is then translated into proteins, with each three-base codon in the mRNA specifying a particular amino acid in the protein chain.

DNA Template: 3'- TACGATCGA -5'
mRNA: 5'- AUGCUAGCU -3'

Translation of the DNA sequence into mRNA with corresponding codons.

RNA: The second nucleic acid

RNA is important for the coding, decoding, regulation, and expression of genes. It plays a variety of roles and exists in different forms, each of which is specialized for a particular function. The primary types of RNA include mRNA, rRNA, and tRNA.

Types of RNA

  • Messenger RNA (mRNA): mRNA is transcribed from DNA and serves as a template for protein synthesis, providing the genetic information needed to produce proteins.
  • Ribosomal RNA (rRNA): rRNA is a component of ribosomes, which are the cell's protein factories. It ensures the proper alignment of mRNA and tRNA and catalyzes the formation of peptide bonds.
  • Transfer RNA (tRNA): tRNA transfers specific amino acids to the ribosome, and matches the appropriate mRNA codon to the corresponding amino acid during protein synthesis.
mRNA tRNA

Illustration of the interaction of mRNA and tRNA in protein synthesis.

RNA functions

RNA is not only essential in protein synthesis, but also contributes to other cellular processes. It can catalyze biochemical reactions, regulate gene expression, and even affect gene silencing.

Protein synthesis

Protein synthesis occurs in two stages: transcription and translation. During transcription, a DNA segment serves as a template to synthesize a complementary mRNA strand. This mRNA then exits the cell nucleus, enters the cytoplasm, and attaches to a ribosome. During translation, the ribosome reads the codons of the mRNA, to which the tRNA brings the appropriate amino acid, forming a polypeptide chain.

Regulation and catalysis

Some RNA molecules also play regulatory roles, such as small interfering RNAs (siRNAs) and microRNAs (miRNAs), which can silence gene expression. In addition, some RNA molecules have catalytic capabilities, known as ribozymes, which can catalyze specific biochemical reactions without proteins.

Conclusion

Nucleic acids, which include DNA and RNA, are fundamental to the biological processes of all living organisms. Their ability to store and transfer genetic information is central to development, reproduction, and cellular function. Understanding nucleic acids uncovers the molecular blueprint of life, revealing how genetic information is preserved, transcribed, translated, and regulated within a cell.


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Nucleic acids

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