Biomolecules (carbohydrates, lipids, proteins and nucleic acids)

Biomolecules Overview
📌 Biomolecules are fundamental to life in every organism, from bacteria to humans, forming their composition and vital functions.
🧪 Carbohydrates (also called glucids, sugars, or hydrates of carbon) are characterized by having Carbon (C), Hydrogen (H), and Oxygen (O) in their composition.
💧 Lipids are the second source of energy/reserve energy and are characterized by having little or no affinity for water, meaning they are hydrophobic.

Carbohydrates: Classification and Examples
🍬 Monosaccharides are single sugar units (like a brick), with Glucose being a key example, having the formula $\text{C}_6\text{H}_{12}\text{O}_6$ and often existing in a cyclic structure in nature.
🍪 Disaccharides (two sugar units) include Lactose (Galactose + Glucose, found in milk) and Sucrose (Glucose + Fructose, common table sugar); their formation releases a molecule of water ($\text{H}_2\text{O}$).
🧱 Polysaccharides involve linking more than two sugar units (like building a wall) and include Starch (energy reserve in plants), Glycogen (glucose reserve in animals), Cellulose (plant structure), and Chitin (arthropod exoskeletons).

Lipids: Types and Functions
🧬 Lipids are classified into fats, triglycerides, phospholipids, and steroids; fats are categorized as saturated (only single bonds between carbons) or unsaturated (containing double bonds, leading to kinks/liquidity).
🔋 Triglycerides are formed by the union of one glycerol molecule and three fatty acids, primarily serving as energy storage.
🛡️ Phospholipids structure the cell membranes as a bilayer, with phosphate groups facing outward (hydrophilic) and fatty acids facing inward (hydrophobic), acting as mediators for substance entry/exit.
⚖️ Steroids, such as cholesterol, have a different ring structure (three 6-carbon rings and one 5-carbon ring) and include hormones like Progesterone (female sexual maturity) and Testosterone (male sexual maturity).

Proteins and Nucleic Acids
🔗 Proteins are formed by chains of amino acids linked together; a molecule is considered a protein if it contains more than 50 amino acids linked in primary, secondary, tertiary, or quaternary structures.
🔬 The primary structure is the simple linear sequence of amino acids, while the secondary structure involves hydrogen bonds forming alpha-helices (like a spring) or beta-pleated sheets.
🌟 Key protein functions include structure (e.g., keratin), transport (carrying molecules like glucose across membranes), and enzymatic roles (accelerating chemical metabolism).
📚 Nucleic Acids (DNA and RNA) are composed of nucleotides (phosphate group, sugar, and nitrogenous base).
↔️ DNA is double-stranded, forming a spiral staircase where the sugar/phosphate form the railings and nitrogenous bases form the steps; bases are complementary: Adenine (A) pairs only with Thymine (T), and Cytosine (C) pairs only with Guanine (G).

Key Points & Insights
➡️ Carbohydrates are the primary source of energy, while lipids serve as the secondary, stored energy reserve; the body uses carbohydrates first before tapping into lipids.
➡️ Amino acids can be compared to 20 essential pearls used to create infinite combinations of necklaces (proteins), provided the total number of beads reaches at least 50.
➡️ DNA acts as a library storing all genetic information, while RNA acts as the student, copying specific sections (like instructions for generating antibodies) and transporting that information out for expression/action without removing the original master copy.
➡️ The key difference between DNA (Deoxyribonucleic acid) and RNA (Ribonucleic acid) lies in their respective sugars, with DNA lacking one oxygen atom (hence 'deoxy').

📸 Video summarized with SummaryTube.com on Feb 04, 2026, 00:28 UTC