Food

Food

  • Importance of food as a source of nutrients, energy, and sustenance for living organisms.

Elements Present in Food

  • Essential elements that compose food include:

    • Carbon (C)

    • Hydrogen (H)

    • Oxygen (O)

    • Nitrogen (N)

    • Phosphorus (P)

    • Sulfur (S)

Dissolved Salts

  • Key elements that are usually found in dissolved salt form include:

    • Sodium (Na)

    • Magnesium (Mg)

    • Chlorine (Cl)

    • Potassium (K)

    • Calcium (Ca)

Trace Elements

  • Definition: Elements that are required in small amounts for various biological processes.

  • Examples of trace elements:

    • Iron (Fe)

    • Copper (Cu)

    • Zinc (Zn)

Biomolecules

  • Definition: Chemicals made inside living organisms that are critical for life.

  • Types of biomolecules include:

    1. Carbohydrates

    2. Lipids (fats, oils)

    3. Proteins

    4. Vitamins

Carbohydrates

  • Composed of Carbon (C), Hydrogen (H), and Oxygen (O) in the ratio of Cx(H2O)y.

  • Example: Glucose (C6H12O6) has twice as much hydrogen as oxygen.

Types of Carbohydrates

  1. Monosaccharides

  2. Disaccharides

  3. Polysaccharides

Monosaccharides

  • Single sugar units.

  • Properties: Sweet taste, soluble in water.

  • Examples:

    • Glucose: main energy source.

    • Fructose: sweeter than glucose.

Disaccharides

  • Composed of two monosaccharides.

  • Properties: Sweet taste, soluble in water.

  • Examples:

    • Sucrose: glucose + fructose.

    • Maltose: glucose + glucose.

    • Lactose: glucose + galactose.

Polysaccharides

  • Composed of multiple monosaccharides.

  • Properties: Generally insoluble in water.

  • Examples:

    • Starch: energy storage.

    • Cellulose: structural component of plant cell walls, aids in digestion.

    • Glycogen: stored energy in the liver.

Sources of Carbohydrates

  • Common dietary sources include grains, fruits, and vegetables.

Lipids

  • Comprised of Carbon (C), Hydrogen (H), and Oxygen (O) without a fixed ratio.

  • State at room temperature:

    • Fats: solid.

    • Oils: liquid.

Differences Between Carbohydrates and Lipids

  • Carbohydrates have a fixed ratio of elements, whereas lipids do not.

  • Lipids generally contain less oxygen than carbohydrates.

Structure of Lipids

Triglycerides

  • Composed of:

    • 1 Glycerol molecule

    • 3 Fatty Acids

Phospholipids

  • Composed of:

    • 1 Glycerol molecule

    • 2 Fatty Acids

    • 1 Phosphate Group (a fatty acid is replaced with a phosphate).

Differences Between Triglycerides and Phospholipids

  • Triglycerides: 1 glycerol + 3 fatty acids.

  • Phospholipids: 1 glycerol + 2 fatty acids + phosphate.

Vitamins

  • Types of vitamins include:

    • Water-soluble (e.g., Vitamin C)

    • Fat-soluble (e.g., Vitamins A, D, E, K)

Water-soluble Vitamins

  • Example: Vitamin C (ascorbic acid)

    • Deficiency: Scurvy

Fat-soluble Vitamins

  • Example: Vitamin D (calciferol)

    • Deficiency: Rickets in children or osteomalacia in adults.

Proteins

  • Composed of Carbon (C), Hydrogen (H), and Nitrogen (N) with small amounts of sulfur and phosphorus.

  • Proteins have a globular (3D) structure.

Structure of Proteins

  • Made of amino acids.

  • Common Amino Acids: There are 20 known amino acids.

  • Bonds between amino acids are peptide bonds.

Peptides and Polypeptides

  • Peptide: less than 20 amino acids.

  • Polypeptide: more than 20 amino acids.

  • Protein: Long polypeptide (at least 200 amino acids).

Types of Proteins

  • Fibrous Proteins: Long and strong (e.g., Keratin in hair/nails).

  • Globular Proteins: Folded structures (e.g., Egg whites, enzymes).

Sources of Proteins

  • Common sources include:

    • Meat

    • Fish

    • Eggs

    • Nuts

Protein Storage in the Body

  • Amino acids are not stored; they are converted to urea in the liver (deamination) and help to form urine.

Prions

  • Misfolded proteins that can lead to diseases such as BSE in cows and CJD in humans.

Energy Transfer Reactions

  • Anabolic Reactions: Build larger molecules from smaller ones (e.g., Photosynthesis).

  • Catabolic Reactions: Break down larger molecules into simpler ones, releasing energy (e.g., Respiration, Digestion).

Minerals in Plants

  • Calcium (Ca): Absorbed from soil; helps bind cell walls together.

  • Magnesium (Mg): Part of the chlorophyll structure.

Minerals in Animals

  • Calcium (Ca): Found in milk, cheese; forms bones and teeth.

  • Iron (Fe): Found in liver, meat; part of hemoglobin.

Importance of Water

  • Acts as a good solvent, participates in chemical reactions, and is essential for movement through membranes and turgidity of cells.

Structural Role of Biomolecules

  • Carbohydrates: Cellulose forms plant cell walls.

  • Proteins: Keratin supports skin and hair structure.

  • Lipids: Provide heat insulation and protection; phospholipids are crucial for cell membrane structure.

Metabolic Role of Biomolecules

  • Carbohydrates and Lipids: Involved in respiration for energy release.

  • Proteins: Serve as enzymes and antibodies.

  • Vitamins: Critical for tissue formation; for example, Vitamin C maintains connective tissues, Vitamin D helps in calcium absorption.

Exam Questions and Answers

  • Familiarize with exam-style questions that may cover various aspects of biomolecules, their roles, and biochemical reactions.