AP Bio Unit 1 Lecture Notes

Overview

• Unit 1: Foundation for AP Biology
  • Focus on chemistry and properties of water
  • Hydrogen bonding
  • Elements of Life
  • Four biomolecule families: carbohydrates, lipids, proteins, nucleic acids (DNA & RNA)

Water and Hydrogen Bonding

• Properties of Water
  • Polar molecule with unequal electron sharing between oxygen and hydrogen
  • Partial negative and positive regions
• Hydrogen Bonds
  • Intermolecular, weak bonds between partial negative oxygen and partial positive hydrogen
  • Present in DNA, RNA, proteins
• Consequences of Hydrogen Bonding
  • Cohesion: hydrogen bonds between water molecules
    • High heat of vaporization, high specific heat, high surface tension
  • Adhesion: water sticking to other substances
    • Transpiration in plants, water adheres to cellulose in plant xylem
  • Surface tension: water surface acts like a net

Acids, Bases, and pH

• Acidic Solutions
  • More hydrogen ions, pH below 7
• Basic Solutions
  • More hydroxide ions, pH above 7
• Importance of pH
  • Conceptual understanding for AP Bio

Elements of Life

• Key Elements: Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur (CHNOPS)
  • Carbon: central to biomolecules
  • Hydrogen: energy exchange, acidity, and energy gradients
  • Phosphorus: in ATP, DNA

Biomolecules: Monomers and Polymers

• Monomers and Polymers
  • Carbohydrates, proteins, nucleic acids built from monomers
  • Monomer analogy: Lego bricks for building polymers
• Dehydration Synthesis
  • Removal of water to combine monomers
• Hydrolysis
  • Addition of water to break polymers
• Functional Groups
  • Phosphate: energy exchange
  • Methyl: nonpolar
  • Hydroxy and Carbonyl: polar, hydrophilic
  • Carboxy and Amino: essential in amino acids
  • Sulfhydryl: protein structure

Carbohydrates and Lipids

• Carbohydrates
  • Monosaccharides: simple sugars (e.g., glucose)
  • Disaccharides: lactose (lactose intolerance)
  • Polysaccharides: energy storage (starch, glycogen), structural (cellulose)
  • Evolution of lactose tolerance in humans
• Lipids
  • Nonpolar, hydrophobic
  • Not composed of repeating monomers
  • Functions: energy storage (fats/oils), waterproofing (waxes), cell membranes (phospholipids), signaling (steroids)

Proteins

• Amino Acids: Monomers of proteins
  • Central carbon, amine group, carboxy group, variable R-group
• Protein Structures
  • Primary: linear sequence of amino acids
  • Secondary: alpha helices, beta sheets from polypeptide backbone interactions
  • Tertiary: interactions between R-groups
  • Quaternary: interactions between multiple polypeptides
• Protein Functions
  • Example: Hemoglobin for oxygen transport; sickle cell disease

Nucleic Acids: DNA and RNA

• Importance
  • DNA: genetic information, heredity
  • RNA: information transfer, can act as enzymes
• Monomers: Nucleotides (sugar, phosphate, nitrogenous base)
  • DNA: deoxyribose, adenine, thymine, cytosine, guanine
  • RNA: ribose, uracil instead of thymine
• Structure of DNA
  • Double helix, sugar-phosphate backbone, hydrogen bonds between bases
  • Directionality: 5' to 3' orientation

Conclusion

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