Ch 2 Macronutrients

Overview of Biological Macromolecules

  • Biological macromolecules include four primary types:
    • Lipids
    • Carbohydrates
    • Nucleic Acids
    • Proteins
  • These are called macromolecules because they are essential biological components synthesized by living organisms.
  • All macromolecules consist of carbon (C), hydrogen (H), and oxygen (O), following the HONC rule where:
    • H = 1, O = 2, N = 3, C = 4 (each carbon atom can form four bonds).

Structure of Carbon Compounds

  • Carbon can form various structures:
    • Straight chains
    • Branched chains
    • Ring structures
  • If a molecule consists solely of carbon and hydrogen, it is termed a hydrocarbon. Examples include:
    • ext{CH}_4 : Methane gas (a hydrocarbon).
  • Hydrophobic Nature of Hydrocarbons:
    • Hydrocarbons are not soluble in water, exhibiting hydrophobic properties.

Functional Groups Involved in Macromolecules

  • All macromolecules contain functional groups that alter their solubility and reactions with other compounds. Some key functional groups include:
    • Hydroxyl Group (-OH): Found in all macromolecules and increases solubility, e.g., in glucose.
    • Carboxyl Group (-COOH): Related to carboxylic acids; vital in biochemical reactions (such as respiration).
    • Amines: Contain nitrogen, act as bases; present in nucleic acids (e.g., DNA, RNA).
    • Phosphates (-PO4): Crucial for energy carriers (like ATP) and phospholipids in cell membranes, also can act like acids.

Definitions Related to Macromolecules

  • Monomer: A single unit (bead) in a chain of macromolecules.
  • Dimer: Two monomers joined together.
  • Polymer: A long chain made up of repeating monomers.
  • Major macromolecules and their monomers:
    • Carbohydrates: Sugar monomers
    • Nucleic Acids: Nucleotide monomers
    • Proteins: Amino acid monomers
    • Lipids: Do not conform to the repeating unit pattern.

Formation and Breakdown of Macromolecules

  • Synthesis: Combining monomers into polymers often involves removing water (dehydration synthesis).
  • Hydrolysis: Adding water breaks apart polymers into monomers.
  • Exemplar Process of Synthesis:
    • From two monomers, pull off the hydroxyl (OH) & hydrogen (H) groups to form water, which combines the monomers into a dimer.
  • Opposite Reaction (Hydrolysis): Add water to split polymers into monomers.

Lipids and Their Characteristics

  • Lipids: Include triglycerides, phospholipids, and steroids.
    • Hydrophobic and water-insoluble.
    • Major functions include energy storage (triglycerides) and structural roles in membranes (phospholipids).
  • Triglycerides:
    • Long-term energy storage; formed by glycerol and three fatty acids.
    • Terminology:
    • Lipogenesis: Making lipids.
    • Lipolysis: Breaking down lipids for energy.
  • Fatty Acids:
    • Differ in saturation levels:
    • Saturated fats: No double bonds, all single bonds.
    • Unsaturated fats: At least one double bond.
    • Polyunsaturated fats: Multiple double bonds.
  • Phospholipids:
    • Amphipathic: One part hydrophilic (water-loving), one part hydrophobic (water-fearing) – crucial for cell membrane structure.
  • Steroids: Derivatives like cholesterol, which serve multiple biological roles, including hormone synthesis and bile production.

Carbohydrates Overview

  • Carbohydrates: Composed of carbon, hydrogen, and oxygen in a 1:2:1 ratio.
    • Simplest forms include monosaccharides (single sugars) such as glucose.
    • Two sugar units lead to disaccharides (e.g., sucrose, lactose), while many can form polysaccharides (e.g., starch, glycogen).
  • Storage:
    • Glycogenesis: Process of forming glycogen from excess glucose.
    • Glycogenolysis: Process of breaking glycogen down into glucose when needed.
    • Gluconeogenesis: Liver synthesis of glucose from non-carbohydrate sources.

Nucleic Acids

  • Nucleic Acids: Include DNA (Deoxyribonucleic Acid) and RNA (Ribonucleic Acid).
    • Nucleotides are the building blocks and consist of a sugar, phosphate group, and nitrogen base.
    • Phosphate-sugar bonds are covalently linked by phosphodiester bonds.
    • Nitrogenous bases categorize into two groups:
    • Purines: Adenine and Guanine (present in both DNA and RNA).
    • Pyrimidines: Cytosine (C), Uracil (U) in RNA, and Thymine (T) in DNA.
  • DNA Structure:
    • Double-stranded, featuring base pairing (A-T, G-C) connected by hydrogen bonds.
  • RNA Structure:
    • Single-stranded; contains uracil in place of thymine, present in both nucleus and cytoplasm.

ATP and Energy Production

  • ATP (Adenosine Triphosphate): Main energy currency of cells.
    • Composed of ribose sugar, three phosphate groups.
    • Energy is released when ATP is hydrolyzed to ADP (Adenosine Diphosphate).
    • Functions as the primary energy source for cellular processes, emphasizing energy dynamics in metabolic training in further chapters.

Summary of Key Concepts

  • Macromolecules: Building blocks of life including lipids, carbohydrates, nucleic acids, and proteins.
  • Interactions and transformations of macromolecules, emphasizing synthesis and breakdown principles vital for biological energy management.
  • Detailed understanding of lipid functionality, carbohydrate metabolism, and the critical roles of nucleic acids in genetic information transfer.