Biological molecules

There are four main types of biological molecules:
1. Carbohydrates: These are your body's main source of energy. They include sugars (like glucose) and starches. They're made of carbon, hydrogen, and oxygen, often in a 1:2:1 ratio.
2. Lipids: These are fats, oils, waxes, and steroids. They're good for long-term energy storage, insulation, and forming cell membranes. Lipids are mostly carbon and hydrogen, making them nonpolar (they don't mix well with water).
3. Proteins: These are the workhorses of the cell. They do almost everything! They act as enzymes (speed up reactions), transport substances, provide structural support, and fight infections. Proteins are made of smaller units called amino acids, linked together. They contain carbon, hydrogen, oxygen, and nitrogen, and sometimes sulfur.
4. Nucleic Acids: These carry genetic information. DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) are nucleic acids. They're made of repeating units called nucleotides. These contain carbon, hydrogen, oxygen, nitrogen, and phosphorus.

Lipids are a broad category of organic molecules characterized by their hydrophobic (water-fearing) nature. This insolubility in water is their defining feature, making them essential for compartmentalization within cells and organisms. We'll focus on three main types:
* Triglycerides
* Phospholipids
* Steroids

Enzymes are essential for life, orchestrating nearly all biochemical reactions within cells. They are almost always proteins, specifically globular proteins, meaning they have a complex 3D shape. This shape is crucial for their function.

The main job of an enzyme is to act as a biological catalyst. A catalyst is something that speeds up a chemical reaction without being consumed or permanently altered in the process.

Carbohydrates are one of the four major classes of biological macromolecules. They're primarily composed of carbon, hydrogen, and oxygen atoms, often in a ratio of 1:2:1 (like C6H12O6 for glucose). You'll hear them called "sugars", "saccharides", or "carbs."

We classify carbohydrates based on how many sugar units they contain:

Proteins are large, complex molecules made up of smaller units called amino acids. There are 20 common types of amino acids, and they can be linked together in almost endless combinations to form long chains. The sequence of these amino acids is determined by your DNA, and this sequence is crucial because it dictates how the protein will fold into its unique 3D structure.

This folding process isn't random; it's a very precise dance driven by the chemical properties of the amino acids in the chain. There are four main levels of protein structure: