Macromolecules Review

Overview of Macromolecules

• Macromolecules refer to large molecules that are fundamental to biological processes. Understanding the four types of macromolecules— carbohydrates, lipids, proteins, and nucleic acids—is crucial for biological sciences.

Types of Macromolecules

• Carbohydrates

  • Empirical formula: CH₂O.

  • Function: Energy storage and supply.

• Lipids

  • Categories include triglycerides, fatty acids, steroids, and phospholipids.

  • Function: Energy storage, structural components of cell membranes, signaling molecules.

• Proteins

  • Function: Catalysis (enzymes), structure, transport, and signaling.

• Nucleic Acids

  • DNA and RNA are primary types.

  • Function: Encoding, transmitting, and expressing genetic information.

Detailed Examination of Carbohydrates

• Monosaccharides

  • Simplest form of carbohydrates; example: glucose.

    • Structure: Six-carbon sugar that forms a six-membered ring.

    • Key feature: Aldehyde functional group in its linear structure.

  • Isomers: Fructose and Glucose

    • Fructose:

      • Structure: Five-membered ring, ketone functional group.

    • Galactose:

      • Structure: Monosaccharide and isomer of glucose, distinguished by differing configuration at carbon four (C4 epimer).

Polysaccharides and Their Functions

• Classification:

  • Starch:

    • Energy storage in plants; includes amylose (straight chain) and amylopectin (branched).

  • Glycogen:

    • Energy storage in animals; highly branched.

  • Chitin:

    • Structural polysaccharide in exoskeleton of insects.

  • Cellulose:

    • Structural polysaccharide in plant cell walls.

Proteins and Their Building Blocks

• Amino Acids:

  • Monomers of proteins; contain carboxyl and amino groups, along with a variable R group.

    • Polypeptides: Chains of amino acids forming proteins.

    • Example of Amino Acids:

      • Amino acid configurations determine protein structure and function.

Identifying Amino Acids

• Characteristics:

  • Have a chiral carbon bonded to an amino group, carboxyl group, hydrogen, and R group.

  • Example: Alanine (R = methyl group).

Protein Formation

• Peptide Bonds:

  • Formed via dehydration synthesis, linking amino acids.

  • Involves loss of a water molecule (H₂O).

  • Results in covalent bond formation.

Enzymes and Their Characteristics

• Enzymes:

  • Proteins that catalyze chemical reactions.

  • Identifying traits: Often end in "ase" (e.g., lactase, protease).

Types of Enzymatic Reactions

• Dehydration Synthesis:

  • Building larger molecules from smaller ones with water lost.

• Hydrolysis:

  • Breaking molecules down by adding water.

Common Proteins and Their Functions

• Hemoglobin:

  • Protein that carries oxygen in blood.

• Myoglobin:

  • Oxygen transporter in muscle tissues.

• Collagen and Keratin: Structural proteins in connective tissues and hair/nails.

Lipids and Their Characteristics

• Lipid Classification:

  • Types include triglycerides, phospholipids, and steroids.

• Fatty Acids:

  • Comprise triglycerides; can be saturated (solid at room temp) or unsaturated (liquid at room temp).

Nitrogenous Bases in Nucleic Acids

• Pyrimidines vs Purines:

  • Pyrimidines: Uracil, Thymine, Cytosine (1 ring).

  • Purines: Adenine, Guanine (2 rings).

Macromolecules and Certain Elements

• Protein Elements:

  • Can contain sulfur (e.g., cysteine) and other elements.

• Nucleic Acids: Contain phosphorus (from phosphate group).

False Statements and Clarifications

• Lipids and Phosphorus:

  • Most do not contain phosphorus, except phospholipids.

• Amino Acids Identification:

  • Some common amino acids end with "in" (e.g., valine).

Summary of Key Concepts

• Recognize the structure and function of the four macromolecule types, understand the similarities/differences between their building blocks, and differentiate between various functional groups and characteristics.

• Be aware of how macromolecules contribute to cellular functions, energy storage, and structural integrity.