Biochemistry and Macromolecules

Biochemistry Overview

Introduction to Chemistry

  • All matter is made of atoms.

  • Atoms combine to form molecules.

  • Molecules combine to form macromolecules, which are essential building blocks for cells.

Macromolecules

  • Biochemistry focuses on macromolecules.

  • There are four main types of macromolecules relevant to biology and nutrition:

  • Carbohydrates

  • Lipids

  • Proteins

  • Nucleic Acids

Formation and Breakdown of Macromolecules

  • Polymers are large complex chains made of smaller units called monomers.

  • Condensation (Dehydration) Reaction:

  • Water is removed to bond monomers together to form polymers.

  • Example: Formation of a longer polymer from unlinked monomers with the removal of water.

  • Hydrolysis Reaction:

  • Water is added to break down polymers into monomers.

  • Example: Splitting a polymer by adding water, breaking a bond.

Chemical Substances in Living Organisms

  • All living organisms consist of chemical substances including carbohydrates, proteins, lipids, and nucleic acids.

  • Chemical reactions are crucial for maintaining life processes.

Carbohydrates

  • Composed of carbon, hydrogen, and oxygen.

  • Three primary types:

  • Monosaccharides:

    • Simplest form of carbohydrates (e.g., Glucose, Fructose).

    • Soluble in water; formula C6H12O6.

    • Sources: Fruits, honey.

  • Disaccharides:

    • Consist of two monosaccharides (e.g., Sucrose, Lactose).

    • Soluble in water; formula C12H22O11.

    • Sources: Table sugar, milk.

  • Polysaccharides:

    • Long chains of monosaccharides (e.g., Starch, Glycogen, Cellulose).

    • Generally insoluble in water.

    • Sources: Bread, potatoes, pasta.

Lipids (Fats)

  • Composed of carbon, hydrogen, and oxygen, with different ratios from carbohydrates.

  • Generally consist of a glycerol unit and fatty acids.

  • Types of fats:

  • Saturated Fats:

    • Solid at room temperature; linked to high cholesterol.

    • Sources: Animal fats, some plants.

  • Unsaturated Fats:

    • Liquid at room temperature; may lower cholesterol levels.

    • Sources: Fish, nuts, seeds, plant oils.

  • Trans Fats:

    • Harmful, formed during hydrogenation; raise bad cholesterol and lower good cholesterol.

  • Cholesterol:

  • Essential for cell membrane structure and hormone production.

  • Excess cholesterol can lead to atherosclerosis, increasing heart disease risk.

Proteins

  • Composed of chains of amino acids folded into unique structures.

  • Include elements Carbon, Hydrogen, Oxygen, Nitrogen (sometimes Phosphorus/Sulfur).

  • There are 20 different amino acids; sequence and combination determine the protein's function.

  • Functions may include enzyme active sites, antibody binding, etc.

Nucleic Acids

  • Include DNA (Deoxyribonucleic acid) and RNA (Ribonucleic acid).

  • DNA Structure:

  • Double helix made up of deoxyribose sugar, nitrogen bases (A, T, G, C) connected by phosphate groups.

  • RNA Structure:

  • Single strand made up of ribose sugar, nitrogen bases (A, U, G, C).

  • Function to carry genetic information.

Food Tests

  • Starch Test:

  • Add iodine to a solution; positive result changes color from yellowish-brown to blue-black.

  • Reducing Sugars Test:

  • Heat with Benedict's reagent; changes from blue to green-yellow-orange-red if reducing sugars are present (not for sucrose).

  • Protein Test:

  • Add Biuret reagent; purple color indicates presence of proteins.

  • Fats Test:

  • Mix with ethanol, then water; cloudy white indicates fats.

  • Vitamin C Test:

  • Add DCPIP; blue color disappears if vitamin C is present.