Introduction to Biochemistry

Introduction to Biochemistry

• Biochemistry is the study of chemical processes within and relating to living organisms.
• It encompasses a wide range of topics, including metabolism, enzyme catalysis, and the structure and function of biomolecules.
• It's a foundational science for understanding biology and medicine.

Biomolecules

• Biomolecules are the essential organic molecules that make up living organisms.
• Major classes of biomolecules include:
  • Carbohydrates: Provide energy and structural support. Examples include sugars, starches, and cellulose.
  • Lipids: Store energy, form cell membranes, and act as hormones. Examples include fats, oils, and steroids.
  • Proteins: Perform a vast array of functions including catalysis, transport, and structural support. Examples are enzymes and antibodies.
  • Nucleic acids: Store and transmit genetic information. Examples are DNA and RNA.
• These molecules interact in complex ways to facilitate life processes.

Metabolism

• Metabolism refers to all the chemical reactions that occur in a living organism to maintain life.
• It can be categorized as:
  • Catabolism: The breakdown of complex molecules into simpler ones, releasing energy.
  • Anabolism: The synthesis of complex molecules from simpler ones, requiring energy.
• Metabolic pathways are a series of linked reactions that convert a substance into another. These pathways are often regulated to maintain homeostasis.

Enzymes

• Enzymes are biological catalysts, typically proteins, that speed up chemical reactions in living organisms without being consumed themselves.
• They lower the activation energy required for reactions to proceed.
• Enzyme activity is affected by factors like temperature, pH, and substrate concentration.
• Enzymes have specific active sites that bind substrates, facilitating the reaction. The specificity of the enzyme for its substrate is crucial.

Cellular Respiration

• Cellular respiration is the process by which cells convert glucose into ATP (adenosine triphosphate), the primary energy currency of cells.
• The process typically involves these stages: glycolysis, the Krebs cycle, and the electron transport chain.
• Aerobic respiration requires oxygen and produces significantly more ATP than anaerobic respiration.

Nucleic Acids: DNA and RNA

• DNA (deoxyribonucleic acid) carries the genetic instructions for building and maintaining an organism.
• It has a double-helix structure with complementary base pairing (A-T, G-C).
• RNA (ribonucleic acid) plays various roles in protein synthesis, including acting as a messenger between DNA and ribosomes.
• RNA has a single-stranded structure, with uracil (U) replacing thymine (T) in its base pairs.

Protein Structure and Function

• Protein structure is hierarchical, organized into primary, secondary, tertiary, and quaternary levels.
• The primary structure is the amino acid sequence.
• Secondary structure, like α-helices and β-sheets, are localized regular folding patterns.
• Tertiary structure is the overall 3D arrangement of the polypeptide chain.
• Quaternary structure describes the arrangement of multiple polypeptide chains in a protein.
• Protein conformation is critical to its function. Changes to shape can affect activity.

Regulation of Biochemical Reactions

• Biochemical reactions are often precisely controlled by various mechanisms to maintain homeostasis.
• Regulation can involve allosteric interactions, feedback inhibition, or covalent modifications of enzymes.
• Hormonal signalling is also a major player in modulating metabolic pathways in the body.

Water

• Water is the most abundant molecule in most living organisms.
• Its properties, such as polarity and ability to form hydrogen bonds, are key to many biochemical processes.
• The polar nature of water allows it to act as a solvent for many polar and ionic substances.

Amino Acids

• Amino acids are the building blocks of proteins.
• There are 20 common amino acids, each with a unique side chain (R group) with particular chemical properties influencing how the proteins fold.
• The side chains determine the overall function of the protein.

pH and Buffers

• pH is a measure of the hydrogen ion concentration in a solution.
• Biological systems maintain a relatively constant pH through buffers, which resist changes in pH.
• Enzymes have optimal pH ranges for activity, and deviations from this range can affect their function.