Molecules of Life

Section 1: Molecules of Life (B.5.A)

Every living organism is constructed from four primary categories of carbon-based structures known as biomolecules. These biomolecules serve a crucial function in the structure and function of the cell, which can be thought of as the foundational "Lego bricks" that make up the architecture of life.

Types of Biomolecules

1. Carbohydrates

• Elements: Carbon (C), Hydrogen (H), Oxygen (O)
• Building Blocks: Monosaccharides (simple sugars)
• Functions:
    - Immediate source of short-term energy for cellular processes.
    - Structural components, particularly in the formation of plant cell walls, predominantly in the form of cellulose.
• Examples:
    - Glucose (a simple sugar),
    - Starch (a polysaccharide used by plants for energy storage),
    - Cellulose (a structural polysaccharide that forms the cell walls of plants).

2. Lipids

• Elements: Carbon (C), Hydrogen (H), Oxygen (O)
• Building Blocks: Glycerol and Fatty Acids
• Functions:
    - Provide long-term energy storage.
    - Form essential components of the cell membrane, creating barriers around cells.
    - Offer insulation to regulate temperature.
    - Protect against water, acting as hydrophobic agents (repelling water).
• Examples:
    - Fats (such as triglycerides),
    - Oils,
    - Waxes,
    - Butters,
    - Cholesterol (a type of lipid important for cell membrane structure).

3. Proteins

• Elements: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N)
• Building Blocks: Amino Acids
• Functions:
    - Perform a vast array of functions inside cells, often referred to as "the workers" of the cell.
    - Act as enzymes, which catalyze and speed up chemical reactions crucial to life processes.
• Examples:
    - Muscle proteins (myosin, actin),
    - Enzymes (such as lactase),
    - Food sources from animals (meat, eggs) and plants (beans).

4. Nucleic Acids

• Elements: Oxygen (O), Nitrogen (N), Phosphorus (P)
• Building Blocks: Nucleotides
• Functions:
    - Serve as repositories for genetic information, determining hereditary traits passed from parents to offspring.
    - Contain instructions for the synthesis of proteins essential for growth, development, and functioning.
• Examples:
    - Deoxyribonucleic Acid (DNA), which stores genetic information,
    - Ribonucleic Acid (RNA), which plays a role in protein synthesis and transmission of genetic information.

In summary, the four biomolecules—carbohydrates, lipids, proteins, and nucleic acids—each contribute essential functions to life, from energy storage and cellular structure to genetic information storage and enzymatic activities.