AP Biology Unit 1 Overview

Foundations of Biology

• Chemistry and properties of water
• Hydrogen bonding
• The Elements of Life
• Four biomolecule families:
  • Carbohydrates
  • Lipids
  • Proteins
  • Nucleic acids (DNA and RNA)

Water and Hydrogen Bonding

• Water is a polar molecule
  • Unequal electron sharing between oxygen and hydrogen
  • Partial negative charge on oxygen, partial positive on hydrogen
• Hydrogen Bonds
  • Intermolecular bonds between molecules
  • Weaker than covalent or ionic bonds
• Hydrogen bonds are crucial in biological molecules such as DNA, RNA, proteins
• Properties due to Hydrogen Bonding:
  • Cohesion: Attraction between water molecules (high heat of vaporization, high specific heat, high surface tension)
  • Adhesion: Water sticks to other substances (e.g., plant xylem)
  • Surface Tension: Water's surface acts like a net

pH and Solutions

• Acidic Solutions: More hydrogen ions, lower pH (below 7)
• Basic Solutions: More hydroxide ions, higher pH (above 7)

Elements of Life

• CHNOPS: Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur
• Key roles:
  • Carbon: Central to biomolecules
  • Hydrogen: Energy exchange, acidity
  • Phosphorus: ATP, DNA

Monomers and Polymers

• Monomers: Building blocks
• Polymers: Large molecules formed by monomers
• Dehydration Synthesis: Process of forming polymers by removing water
• Hydrolysis: Breaking polymers into monomers by adding water

Functional Groups

• Phosphate Groups: Energy exchange (ATP)
• Methyl Groups: DNA silencing, nonpolar
• Hydroxy and Carbonyl Groups: Make molecules hydrophilic
• Carboxyl and Amino Groups: Essential in amino acids
• Sulfhydryl Group: Protein stabilization

Carbohydrates

• Monosaccharides: Simple sugars (e.g., glucose)
• Disaccharides: Two linked monosaccharides (e.g., lactose)
• Polysaccharides: Energy storage and structural roles
  • Starch (plants), Glycogen (animals), Cellulose (plants)

Lipids

• Characteristics: Nonpolar, hydrophobic, not composed of repeating monomers
• Functions:
  • Energy storage (fats and oils)
  • Waterproofing (waxes)
  • Membrane structure (phospholipids)
  • Signaling (steroids)

Proteins

• Monomer: Amino acid
• Protein Structures:
  • Primary: Sequence of amino acids
  • Secondary: Formations like alpha helix and pleated sheet
  • Tertiary: 3D structure formed by R group interactions
  • Quaternary: Interaction of multiple polypeptide chains
• Example: Hemoglobin structure and sickle cell disease

Nucleic Acids

• DNA and RNA: Molecules of genetic information
• DNA: Double helix, consists of nucleotide strands
• RNA: Single-stranded, various forms, roles in protein synthesis
• Nucleotide Structure:
  • Five-carbon sugar
  • Phosphate group
  • One of four nitrogenous bases
• Directionality: Built from 5' to 3' end

Study and Resource Tips

• Use resources like LearnBiology.com for quizzes, flashcards, and tutorials
• Access free trials to improve understanding and confidence in biology concepts