Biology: Biomolecules

• Biomolecules are organic molecules essential for life.
• The four major types of biomolecules are carbohydrates, lipids, proteins, and nucleic acids.

Carbohydrates

• Serve as a primary source of quick energy
• Provide structural support in plants in the form of cellulose
• Monosaccharides, or simple sugars, are the building blocks of carbohydrates, with examples including glucose, fructose, and galactose.
• Disaccharides are formed when two monosaccharides join together, such as sucrose (table sugar), lactose (milk sugar), and maltose.
• Polysaccharides are composed of many monosaccharides, with examples including starch (energy storage in plants), glycogen (energy storage in animals), cellulose (structural support in plants), and chitin (structural support in arthropods and fungi).
• The key bond in carbohydrates is the glycosidic bond.

Lipids

• Function in long-term energy storage
• Serve as components of cell membranes (phospholipids)
• Provide insulation
• Facilitate hormone production (steroids)
• Types of lipids include triglycerides (fats and oils), phospholipids (cell membranes), steroids (cholesterol, hormones), and waxes.
• The building blocks of lipids are fatty acids and glycerol.
• Saturated fatty acids have no double bonds and are solid at room temperature (e.g., animal fats).
• Unsaturated fatty acids contain double bonds and are liquid at room temperature (e.g., plant oils).
• The key bond in lipids is the ester bond.

Proteins

• Function as enzymes to catalyze reactions
• Provide structural support, e.g., collagen and keratin
• Transport substances, e.g., hemoglobin
• Defend the immune system via antibodies
• Enable movement, e.g., actin and myosin
• The building blocks of proteins are amino acids.
• The primary structure of proteins is the sequence of amino acids.
• The secondary structure involves local folding, such as alpha-helices and beta-sheets.
• The tertiary structure refers to the 3D shape of a single polypeptide.
• The quaternary structure involves the arrangement of multiple polypeptides.
• Denaturation is the loss of protein structure due to factors like heat and pH.
• The key bond in proteins is the peptide bond.

Nucleic Acids

• Function in the storage and transmission of genetic information
• Types include DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
• The building blocks are nucleotides, which consist of a phosphate group, sugar (deoxyribose or ribose), and nitrogenous base.
• Nitrogenous bases in DNA: adenine (A), guanine (G), cytosine (C), and thymine (T)
• Nitrogenous bases in RNA: adenine (A), guanine (G), cytosine (C), and uracil (U)
• The key bond in nucleic acids is the phosphodiester bond.
• DNA has a double helix structure with complementary base pairing (A-T, G-C).
• RNA is single-stranded.

Additional Information

• Anabolism: The process of building complex molecules from simpler ones (ADD).
• Catabolism: The process of breaking down complex molecules into simpler ones (CUT).
• Dehydration Synthesis (Condensation): Joining molecules by removing water.
• Hydrolysis: Breaking molecules by adding water.