Biomolecules

Biomolecules

Definitions

  • Monomer: Molecule that can react with other molecules to form large molecules (polymers).

  • Polymer: Large molecular structures formed by the linkage of monomers.

Polymers

Characteristics

  • Long molecules formed by chains of repeating small units (monomers).

  • Bonds formed through covalent bonding (shared pairs of electrons).

Formation and Breakdown

  • Condensation Reaction: Combines monomers by removing water to form new bonds.

  • Hydrolysis: Breaks polymers by adding water to split the bonds.

Condensation and Hydrolysis Reactions

  • Dehydration Reaction: Removal of water during polymer formation.

  • Hydrolysis Reaction: Addition of water to split bonds between subunits.

Biological Macromolecules

Examples and Groups

  • Proteins: Functional and structural components.

    • Amino acids as building blocks.

  • Carbohydrates or Glycans: Simple sugars (monosaccharides) forming larger structures.

    • Functions: Storage of chemical energy and structural roles.

Carbohydrates Structure

  • Formula: (CH2O)n; e.g., Glucose C6H12O6.

Simple Sugars (Monosaccharides)

Structure

  • Backbone of carbon atoms linked by single bonds.

  • Each carbon atom linked to a hydroxyl group except one with a carbonyl group (C=O).

Functions

  • Can react with proteins (e.g., hemoglobin) in their open chain form, affecting diabetes tracking via modified hemoglobin A1c.

Isomers

Types

  • Structural Isomers: Different structures in their carbon skeleton.

  • Stereoisomers: Same structure, different spatial arrangements.

    • Enantiomers: Mirror images (chiral molecules).

Chiral Molecules

Specific Forms

  • D-glyceraldehyde: Hydroxyl group on carbon projects to the right.

  • L-glyceraldehyde: Hydroxyl group on carbon projects to the left.

Disaccharides

Function

  • Effective reservoirs of glucose; transport forms of sugars.

Examples

  1. Sucrose: Glucose + Fructose.

    • Major component of plant sap.

  2. Lactose: Glucose + Galactose.

    • Present in mammalian milk for newborns.

Oligosaccharides

  • Composed of a few sugars; involved in cellular interactions.

  • Found in glycolipids and glycoproteins on cell surfaces.

Polysaccharides

Glycogen

  • Polymer of glucose; stored in liver.

  • Responsible for glucose homeostasis.

Starch

  • Storage form in plants; composed of amylose and amylopectin.

  • Amylose: Unbranched; Amylopectin: Branched structure.

Cellulose

  • Structural polysaccharide; makes up plant cell walls.

  • Composed of β-linked glucose.

Chitin

  • Unbranched polymer of N-acetylglucosamine.

  • Major structural component in invertebrates.

  • Provides resilience and flexibility for exoskeletons.

Lipids

Definition

  • Lipids: Nonpolar biological molecules that dissolve in organic solvents (i.e., fats, oils).

Types

  1. Fats (Triacylglycerol): Consists of glycerol and three fatty acids.

  2. Phospholipids: Contains two fatty acid tails linked to a phosphate group.

Proteins

General Information

  • Linear polymers made from 20 different amino acids.

  • Functions: Facilitate chemical reactions, transport molecules, provide structure, and defense.

Structure and Function

  • Each protein has a unique sequence of amino acids affecting its structure and function.

Amino Acids

Structure

  • Composed of an amino group, carboxyl group, hydrogen, and R-group.

  • Participate in forming polypeptides.

Characteristics of R-groups

  1. Polar, Charged: Form ionic bonds and are mostly fully charged.

  2. Polar, Uncharged: Can form hydrogen bonds; reactive.

  3. Nonpolar: Hydrophobic, tend to fold into protein interiors.

Protein Structure

Levels of Structure

  1. Primary: Amino acid sequence.

  2. Secondary: Alpha-helices and beta-sheets.

  3. Tertiary: 3D shape; includes multiple secondary structures.

  4. Quaternary: Assembly of multiple polypeptide chains.

Protein Folding and Chaperones

  • Chaperones: Assist in folding proteins and preventing aggregation.

  • Denaturation: Unfolding of proteins due to environmental changes (pH, temperature).

Nucleic Acids

General Information

  • Long polymers of nucleotides (DNA & RNA).

  • DNA encodes genetic material, while RNA translates DNA to proteins.

Structure of Nucleotides

  1. Five-carbon sugar (ribose/deoxyribose).

  2. Phosphate group.

  3. Nitrogenous base: Purines (A, G) and Pyrimidines (C, T, U).

Summary of Nucleic Acids

  • DNA: Double-stranded; stores hereditary information.

  • RNA: Single-stranded; involved in protein synthesis.

Key Roles

  • ATP and GTP act as energy carriers for cellular processes.

  • NAD+ and FAD used in electron transport.