Macromolecules

Macromolecules Overview

Lessons and Learning Targets

• Learning Targets:

  • Describe basic structures and functions of carbohydrates, lipids, proteins, and nucleic acids.

  • Draw glucose, a nucleotide, an amino acid, and a phospholipid.

  • Draw hydrolysis and dehydration synthesis reactions of glucose, nucleotide, amino acid, and phospholipid.

  • Design and conduct controlled experiments.

• Materials/Resources:

  • Laptop

  • Pen/pencil/notebook

  • Unit 1 slides/Anchor guides 1-4

Monomer vs. Polymer

• Monomer: Refers to a single unit of a macromolecule. Examples include:

  • One glucose molecule

  • One amino acid

  • One nucleotide

• Polymer: Refers to many units (monomers) of macromolecules. Examples include:

  • A long chain of glucose is called starch (a carbohydrate).

  • A long chain of amino acids form proteins.

  • Lipids do not constitute true polymers.

  • A long chain of nucleotides forms DNA or RNA.

Carbohydrates

• Definition & Composition:

  • Composed of Carbon (C), Hydrogen (H), and Oxygen (O).

  • Primarily serve as a quick energy source.

• Monomers:

  • Monosaccharides: Single sugars (e.g., Glucose, Fructose, Ribose).

• Dimers:

  • Disaccharides: Formed from two monosaccharides (e.g., Lactose, Maltose, Sucrose).

• Polymers:

  • Polysaccharides: Long chains of monosaccharides serving structural roles (e.g., Cellulose in plant cell walls).

Examples of Carbohydrates:

• Monosaccharides:

  • Glucose, Fructose, Ribose.

• Disaccharides:

  • Lactose (Galactose + Glucose)

  • Maltose (Glucose + Glucose)

  • Sucrose (Glucose + Fructose)

• Polysaccharides:

  • Cellulose, Glycogen, and Starch (Amylose and Amylopectin).

Dehydration & Hydrolysis Reactions

• Dehydration Reaction:

  • Occurs between two monosaccharides to form a disaccharide by removing a water molecule (H2O) and forming a glycosidic bond using hydroxyl (OH) groups.

• Hydrolysis Reaction:

  • The addition of water (H2O) breaks down disaccharides back into monosaccharides, reforming hydroxyl (OH) groups.

Starch Variants

• Starch: A polysaccharide made of a long chain of glucose.

  • Amylose: A linear polymer.

  • Amylopectin: A branched polymer requiring more digestion to access energy compared to monosaccharides.

Glycogen

• Definition:

  • A polysaccharide created in the liver for glucose storage.

  • Has a branched chain structure with $ ext{a(1-6)}$ and $ ext{a(1-4)}$ linkages.

Cellulose

• Definition:

  • A structural polysaccharide that forms plant cell walls.

  • Comprised of beta-glucose structures that human enzymes cannot break down, only certain bacteria can.

Chitin

• Definition:

  • A polysaccharide found in fungal cell walls and insect exoskeletons.

Proteins

• Role of Proteins:

  • Proteins perform most cellular functions and are coded by DNA.

• Monomer:

  • Amino acid, consisting of:

  • Amino group

  • Carboxyl group

  • Variable side chain (R group)

Protein Functions (Table 5.1)

• Structural Proteins: Support (e.g., Collagen in connective tissues).

• Storage Proteins: Supply amino acids (e.g., Casein in milk).

• Transport Proteins: Transfer substances (e.g., Hemoglobin for oxygen transport).

• Hormonal Proteins: Regulate body functions (e.g., Insulin).

• Receptor Proteins: Relay signals (e.g., nerve cell receptors).

• Contractile Proteins: Facilitate movement (e.g., Actin and Myosin muscles).

• Defensive Proteins: Protect against pathogens (e.g., Antibodies).

• Enzymatic Proteins: Catalyze biochemical reactions (e.g., Digestive enzymes).

Protein Structure

• Primary Structure: Sequence of amino acids.

• Secondary Structure: Localized folding (alpha-helices and beta-pleated sheets).

• Tertiary Structure: Overall 3D structure due to R group interactions.

• Quaternary Structure: Complex of multiple polypeptides.

Stability Factors

• Bonds stabilizing tertiary and quaternary structures include:

  • Hydrogen bonds, ionic bonds, covalent (disulfide bridges), and hydrophobic interactions.

Lipids

• Major Classes of Lipids:

  • Triglycerides: One glycerol + 3 fatty acids.

  • Phospholipids: Form membranes in cells.

  • Waxes: Protective coatings.

  • Hormones: Include steroids like cholesterol.

• Energy Density: Lipids are calorie-dense; provide 9 Cal/g.

Triglycerides

• Formed from glycerol and fatty acids through dehydration synthesis, creating ester linkages.

Saturated vs. Unsaturated Fats

• Saturated Fat:

  • Solid at room temperature; no double bonds between carbons (e.g., animal fats).

• Unsaturated Fat:

  • Liquid at room temperature; contains at least one double bond causing bends (e.g., plant oils).

Digestion of Macromolecules

• Process Overview:

  1. Consumption of organic matter (carbs).

  2. Digestion: Enzymes hydrolyze large carbohydrates into monosaccharides.

  3. Absorption: Monosaccharides enter the bloodstream to be utilized for energy or as building blocks in biosynthesis.

Enzymes

• Key Concepts:

  • Substrate: The reactant molecule that binds to the enzyme's active site.

  • Products: The outcomes created through the enzyme’s action.

  • Factors Affecting Activity:

  • Temperature: Optimum ranges for enzyme efficiency.

  • pH levels: Specific pH for different enzymes.

  • Substrate and enzyme concentrations influence rates of reactions.

Photosynthesis and Biosynthesis

• Photosynthesis: Conversion of CO2 and H2O into glucose using sunlight with the equation:
  6CO2 + 6H2O + ext{light energy}
  ightarrow C6H{12}O6 + 6O2

• Glucose serves as the foundation for synthesizing macromolecules essential for plant growth, including starches, proteins, and lipids.

Conclusion

• Understanding structural and functional aspects of macromolecules is crucial for comprehending biological processes and the chemistry of life. Relationships and transformations among carbohydrates, proteins, and lipids demonstrate their interconnected roles in living systems, including enzymatic and metabolic functions that facilitate growth and energy utilization.