Biochemistry I - Carbohydrates Overview

Biochemistry I - Course Overview

• Biochemistry is the study of chemical substances and processes in living organisms, including changes during development and life.
• It includes organic molecules and their chemical reactions.
• Key biomolecules are carbohydrates, amino acids, lipids, proteins, and nucleic acids.

Carbohydrates (Chap I)

• Carbohydrates are organic compounds containing carbon, hydrogen, and oxygen.

• They're formed in plants through photosynthesis from carbon dioxide and water in the presence of sunlight.

• Examples include sugars, starches, and fibers in fruits, grains, vegetables, and milk products.

• The general formula is Cn(H₂O)n.

• The simplest carbohydrates are called monosaccharides.

• Monosaccharides link to form oligosaccharides and polysaccharides.

• All monosaccharides are aldehydes or ketones and contain several hydroxyl groups.

• Functions of carbohydrates:

  • Energy storage and production (glycogen, starch)
  • Plant cell wall structure (cellulose, chitin)
  • Immune response, cell-cell interactions, fertilization, and viral infection.
  • Protein-saving action: preventing protein use for energy when adequate carbohydrates are present.
  • Lipid metabolism: excess carbohydrates can be converted to fatty acids and triglycerides in the liver.

• Flavor and Sweeteners: Carbohydrates provide sweetness in foods. Receptors in the tongue bind to carbohydrates, sending a "sweet" signal to the brain. Fructose is the sweetest, followed by sucrose, then glucose.

• Biological Recognition Processes: Carbohydrates are also important in cellular recognition. Many immunoglobulins (antibodies) and peptide hormones contain glycoprotein sequences composed of amino acids linked to carbohydrates.

• Classes of carbohydrates:

  • Monosaccharides: cannot be hydrolyzed to simpler carbohydrates (e.g., glucose, fructose, galactose).
  • Oligosaccharides: formed by short chains of monosaccharides (2 to 20) linked by glycosidic bonds (e.g., sucrose, lactose, maltose).
  • Polysaccharides: polymers of 20 to thousands of monosaccharides (e.g., starch, glycogen, cellulose, chitin).

• Specific polysaccharides:

  • Starch: abundant in plants, a mix of amylose (linear) and amylopectin (branched) which stores glucose.
  • Glycogen: animal starch, branched, stores glucose.
  • Cellulose: plant cell wall, structural component, cannot be digested by humans.
  • Chitin: exoskeletons of crustaceans and insects, fungal cell walls.

• Nomenclature: Monosaccharides are named based on the number of carbons (e.g., triose, pentose, hexose) and their functional group (aldehyde or ketone).

Amino Acids and Proteins (Chap II)

• Covers roles of proteins in living organisms, properties of 20 essential amino acids, peptide bond formation and properties, protein folding (secondary, tertiary, quaternary structures), and protein denaturation.

Nucleic Acids (Chap II)

• Covers the role of nucleic acids in living organisms.
• Includes nomenclature, chemical composition, and structures of nucleosides and nucleotides.
• Discusses structure of DNA double helix, DNA packaging, and replication.
• Includes mutations and repair mechanisms, transcription, genetic code, translation, and DNA sequencing.

Lipids (Chap IV)

• Covers roles of lipids in living organisms, classification of lipids, fatty acids (saturated, unsaturated), glycerides (neutral glycerides, phosphoglycerides), non-glycerol lipids (sphingolipids, steroids, waxes), and biological membranes (structure, transport across membranes).

Natural Products (Component III)

• General definition and classification of natural products.
• Covers examples like semi-chemicals, lipids, alkaloids, phenylpropanoids, polyketides, terpenoids, saponins, and flavonoids.

General Biochemistry Introduction

• Biochemistry is the study of the chemical substances and processes that occur in living organisms, including changes during development and life.
• Key biomolecules are carbohydrates, amino acids, lipids, proteins, and nucleic acids.

Importance of Biochemistry

• used in different domains such as food science (chemical composition, shelf life), agriculture (interaction of herbicides/insecticides with plants), pharmacology/physiology/microbiology/toxicology/clinical chemistry (drug action), and the study of disease diagnosis/therapy.
• Biotechnology industry: produces disease-resistant seeds, drought-resistant plants, and seed coatings.
• Pharmaceutical industry: drug production.
• Biochemistry is used to learn about biological processes and properties of biomolecules (e.g., keratin in shampoo, food additives, artificial sweeteners).
• Gene therapy is within the realm of biochemistry to understand chemical reactions involved.