Chapter_3

The Chemical Basis of Life: Organic Molecules

Page 1

• Introduction to organic molecules and their significance in biology.

Page 2

• Organic Chemistry

  • Organic molecules contain Carbon (C) and Hydrogen (H).

  • Abundant in living organisms.

  • Macromolecules: Large, complex organic molecules.

  • Four categories of macromolecules:

    • Carbohydrates

    • Lipids

    • Proteins

    • Nucleic Acids

  • Bacterial cells contain ~5000 different organic molecules; plant or animal cells have double that number.

Page 3

• Inorganic Molecules vs. Organic Molecules

  • Organic molecules usually contain carbon and hydrogen.

  • Inorganic molecules typically contain positive and negative ions.

  • Organic molecules predominantly involve covalent bonding, while inorganic molecules often involve ionic bonding.

  • Organic compounds are generally larger and mainly associated with living organisms.

Page 4

• Classes of Organic Molecules

  • Carbohydrates, lipids, proteins, and nucleic acids are termed macromolecules due to their size.

  • Polymers are made of smaller units known as monomers.

  • For example, proteins (polymers) can contain hundreds of amino acids (monomers).

Page 5

• Polymer Formation

  • Dehydration: Monomers combine, eliminating water to form polymers.

  • Hydrolysis: Adding water breaks down polymers into monomers.

Page 6

• Fatty Acid and Glycerol Structure

  • Diagrams depicting the chemical structures of stearic acid and glycerol.

  • Formation and breakdown through dehydration and hydrolysis are noted.

Page 7

• Sucrose Formation

  • Sucrose (C12H22O11) is formed from glucose and fructose through hydrolysis with sucrase enzyme.

Page 8

• Carbohydrates

  • Serve as immediate energy sources.

  • Composed of C, H, and O (General Formula: Cn(H2O)n).

  • Have structural roles in organisms.

  • Include single sugar molecules and chains of sugars.

Page 9

• Monosaccharides

  • Simplest sugars; ready source of energy.

  • Molecular formula is a multiple of CH2O.

  • Have hydroxyl groups, making them soluble in water.

  • Common structures: Pentoses (5C sugars like ribose and deoxyribose) and Hexoses (6C sugars like glucose).

Page 10

• Glucose Isomers

  • Structural Isomers: Different arrangements of elements (e.g., glucose vs. galactose).

  • Stereoisomers: Different spatial arrangements (e.g., α-glucose vs. β-glucose).

Page 11

• Disaccharides

  • Composed of two monosaccharides joined through a dehydration reaction.

  • Examples:

    • Sucrose: Glucose + Fructose.

    • Maltose: Glucose + Glucose.

    • Lactose: Glucose + Galactose.

Page 12

• Polysaccharides

  • Long chains of monosaccharides; play roles in short-term energy storage.

  • Large and insoluble; cannot pass through plasma membranes easily.

  • Examples:

    • Starch in plants for energy storage.

    • Glycogen in animals for energy storage.

    • Structural roles: Cellulose in plants, chitin in insects and fungi.

Page 13

• Starch and Glycogen

  • Starch consists of amylose and amylopectin, polymers of glucose for energy storage in plants.

  • Glycogen is stored in liver granules and functions as short-term energy in animals.

Page 14

• Cellulose and Structural Polysaccharides

  • Cellulose: Polymer of β-glucose; major component of plant cell walls.

  • Chitin: Forms exoskeleton of insects and fungal cell walls.

  • Glycosaminoglycans: Found in animals, especially cartilage.

Page 15

• Lipids

  • Composed mainly of hydrogen and carbon; nonpolar, making them insoluble in water.

  • Used for insulation and long-term energy storage by animals; oil is used by plants.

Page 16

• Fats

  • Mixtures of triglycerides (triacylglycerols).

  • Formed by bonding glycerol with three fatty acids through dehydration.

  • Fatty acids consist of long hydrocarbon chains.

Page 17

• Types of Fatty Acids

  • Can vary: all same, all different, or a mix.

Page 18

• Saturated vs. Unsaturated Fatty Acids

  • Saturated: No double bonds between carbons; solid at room temperature.

  • Unsaturated: At least one double bond; generally liquid at room temperature.

  • Fats store more energy than carbohydrates and have structural roles.

Page 19

• Visual Representation of Saturated and Unsaturated Fatty Acids

  • Illustrations of chemical structures for both types of fatty acids.

Page 20

• Phospholipids

  • Membrane components with hydrophilic heads and hydrophobic tails.

  • Essential for forming the phospholipid bilayer in cell membranes.

Page 21

• Steroids

  • Characterized by four interconnected carbon rings.

  • Include cholesterol and hormones like testosterone and estrogen.

Page 22

• Waxes

  • Long-chain fatty acids and alcohol; waterproof barriers in plants and animals (e.g., bee hives).

Page 23

• Functions of Proteins

  • Support (keratin), enzyme activity, transport (hemoglobin), defense (antibodies), hormones (insulin), motion (actin/myosin).

  • Composed of C, H, O, N, and sometimes S (sulfur).

Page 24

• Classification of Amino Acids

  • Based on side chain properties: acidic, basic, hydrophilic, hydrophobic.

Page 25

• Amino Acid Structure and Genetic Code

  • Depicts codons related to specific amino acids with a focus on mRNA sequences.

Page 26

• Peptide Bond Formation

  • Amino acids join via peptide bonds through dehydration.

  • Diagrams illustrating the creation of peptide chains.

Page 27

• Polypeptide Structure

  • Information on N-terminus and C-terminus ends of polypeptides; peptide bond formation depicted.

Page 28

• Protein Structure Levels

  • Primary: Sequence of amino acids.

  • Secondary: Coiling or folding structures (α-helices, β-pleated sheets).

  • Tertiary: 3D shape formation.

  • Quaternary: Multiple polypeptides combined.

Page 29

• Characteristics of Protein Structure

  • Influences from specific interactions (hydrogen, ionic, hydrophobic effects, van der Waals forces, disulfide bridges).

Page 30

• Protein Interaction and Stability

  • Importance of protein interactions in cellular processes and how structure influences functionality.

Page 31

• Functional Domains in Proteins

  • Distinct modules within proteins that contribute to their biological functions.

  • Example is the STAT protein, illustrating the importance of domain function.

Page 32

• Nucleic Acids

  • Store, express, and transmit genetic information.

  • Two classes: DNA (stores genetic info) and RNA (codes for proteins).

Page 33

• Nucleotide Structure

  • Composed of a phosphate group, a 5C sugar, and nitrogenous bases.

Page 34

• DNA vs. RNA

  • Differences include sugar type (deoxyribose vs. ribose), bases (thymine vs. uracil), and structural forms (double vs. single-stranded).