Biomolecules and Carbohydrates

Biomolecules

• Biomolecules are large molecules necessary for life, built from smaller chemical components like carbon, oxygen, nitrogen, hydrogen, phosphorus, and sulfur.
• Examples of hydrogen-based molecules include water (H₂O), ammonia (NH₃), methane (CH₄), and table sugar (C₁₂H₂₂O₁₁).
• Biomolecules are often listed on nutritional labels.
• Micronutrient deficiencies, like anemia caused by lack of iron, folate, or vitamin B12, can result from inadequate intake of essential vitamins and minerals.
• Biomolecules are the fuel for metabolism - chemical reactions occurring in the body's cells that transform food into energy for bodily functions.

Carbohydrates

• Carbohydrates are abundant organic compounds, comprising over 75% of plant dry weight, primarily made up of carbon, hydrogen, and oxygen in a 1:2:1 ratio.
• Types of carbohydrates include:
  • Monosaccharides (simple sugars) like glucose, fructose, and galactose.
  • Disaccharides (two monosaccharides) like sucrose, lactose, and maltose.
  • Polysaccharides (many monosaccharides) like starch, glycogen, and cellulose.

Monosaccharides

• Monosaccharides are the building blocks of carbohydrates.
• They are classified as either aldoses (aldehyde group) or ketoses (ketone group).
• Examples include:
  • Glucose (C₆H₁₂O₆): A key hexose (6-carbon sugar), vital for energy.
  • Fructose (C₆H₁₂O₆): Found in fruit, honey, and sometimes processed foods.
• Some important derivatives include ascorbic acid (vitamin C) and sugar alcohols (e.g., sorbitol).

Disaccharides

• Disaccharides are formed by the condensation of two monosaccharides, releasing a water molecule.
• Examples include:
  • Sucrose: table sugar, a combination of glucose and fructose.
  • Lactose: Found in dairy products, a combination of glucose and galactose.
  • Maltose: Less sweet than the others, found in beer production, a combination of two glucoses.

Polysaccharides

• Polysaccharides are complex carbohydrates composed of many monosaccharides linked together.
• Examples include:
  • Cellulose: An insoluble fiber, structural component of plant cell walls, aids in food movement through the digestive system.
  • Glycogen: A branched polysaccharide, serves as energy storage in animals and fungi.
  • Pectin: A soluble fiber, found in fruits and vegetables, aids digestion.
  • Chitin: A structural polysaccharide, found in insect exoskeletons and fungal cell walls, has antibacterial and antiviral properties.

Lipids

• Lipids are hydrophobic biomolecules containing chains of hydrocarbons, important for long-term energy storage and insulation.
• Types of lipids include:
  • Triglycerides: Composed of glycerol and three fatty acids, can be saturated (single bonds) or unsaturated (double bonds). Saturated fats are solid at room temperature, while unsaturated fats are liquid.
  • Phospholipids: Similar to fats but with a phosphate group, form the cell membrane's phospholipid bilayer. Hydrophobic tails face inward, hydrophilic heads face outward.
  • Steroids: Complex lipids with fused carbon ring structures, help regulate metabolism, immune responses, and reproduction.

Proteins

• Proteins are diverse biomolecules crucial for muscle growth, defense, metabolism, and other bodily functions.
• They are composed of chains of amino acids linked by peptide bonds.
• The sequence of amino acids determines the protein's properties and functions.
• There are four levels to protein structure:
  • Primary structure: linear sequence of amino acids.
  • Secondary structure: formed by hydrogen bonds, creating shapes like alpha helices and beta pleated sheets.
  • Tertiary structure: three-dimensional structure formed by interactions between amino acid side chains, can be fibrous or globular.
  • Quaternary structure: formed when multiple polypeptide chains interact via hydrogen bonds.

Nucleic Acids

• Nucleic acids are large organic molecules composed of nucleotide units, each containing:
  • A nitrogenous base (purines: adenine and guanine; pyrimidines: cytosine and thymine/uracil).
  • A five-carbon sugar (ribose or deoxyribose).
  • One or more phosphate groups.
• Types of nucleic acids include:
  • DNA (Deoxyribonucleic Acid): Contains deoxyribose sugar and four nucleotides (adenine, guanine, cytosine, thymine), carries genetic information for cellular activities.
  • RNA (Ribonucleic Acid): Contains ribose sugar and four nucleotides (adenine, guanine, cytosine, uracil), involved in encoding and decoding genetic information.
• ATP (Adenosine Triphosphate): A special nucleotide, provides the highest-energy source in cells.

Hormones

• Sex hormones:
  • Testosterone: Male sex hormone, synthesized from cholesterol.
  • Progesterone and Estrogen (Estradiol): Female sex hormones, synthesized from cholesterol.
• Adrenocorticoid hormones:
  • Aldosterone: Regulates sodium and potassium levels in the kidneys.
  • Cortisol: A glucocorticoid, helps regulate energy metabolism and reduce inflammation.

Waxes

• Waxes are hydrophobic esters made of alcohols and fatty acids, found in nature as protective coatings on plants and animals.
• They are transparent, less viscous, and have a high melting point, providing waterproofing and protection.
• Examples include cerumen (earwax), beeswax, and carnuba wax.

Essential, Nonessential, and Conditional Amino Acids

• Essential amino acids cannot be produced by the body and must be obtained from the diet.
• Nonessential amino acids can be synthesized by the body.
• Conditional amino acids are usually nonessential but can become essential during illness or stress.