AP Biology Unit 1 – Chemistry of Life: Ultimate Study Notes (CED aligned)

Water Properties

Polarity and Hydrogen Bonding

  • Water is polar (unequal sharing of electrons)

  • Oxygen is partially negative, hydrogens are partially positive

  • Hydrogen bonds form between water molecules

  • Individual hydrogen bonds are weak, but many together are strong

Key Effects of Polarity

  • Enables hydrogen bonding

  • Allows water to interact with other polar molecules

  • Contributes to life-supporting properties

Emergent Properties of Water

Cohesion and Adhesion

  • Cohesion: water sticks to itself

  • Adhesion: water sticks to other surfaces

  • Important for water transport in plants

Temperature and Surface Properties

  • High specific heat: resists temperature change

  • Surface tension: strong attraction at surface

  • Cause → Effect

    • Hydrogen bonding → cohesion → water movement in plants

    • High specific heat → temperature stability → homeostasis

  • Tips

    • Always mention hydrogen bonding in FRQs

    • Use phrase: "This property of water allows..."

Water and Life Function

Biological Importance

  • Stabilizes environments

  • Acts as a solvent

  • Supports biochemical reactions

Macromolecules

Carbohydrates

Structure and Function

  • Monomers: monosaccharides

  • Provide quick energy

  • Structural roles (cellulose in plants)

Lipids

Structure and Function

  • Nonpolar and hydrophobic

  • Long-term energy storage

  • Phospholipids form cell membranes

  • Not true polymers

Proteins

Structure Levels

  • Primary: amino acid sequence

  • Secondary: hydrogen bonding

  • Tertiary: 3D folding

  • Quaternary: multiple polypeptides

Function

  • Enzymes

  • Structural support

  • Transport

  • Cause → Effect

    • Change in structure → change in function

    • Denaturation → loss of function

Nucleic Acids

Structure and Function

  • DNA and RNA

  • Store and transmit genetic information

  • Tips

    • Structure determines function is key

    • For protein questions, always mention shape

Enzymes

Enzyme Function

Catalytic Role

  • Speed up chemical reactions

  • Lower activation energy

  • Not consumed in reactions

Enzyme-Substrate Interaction

Binding Process

  • Substrate binds to active site

  • Forms enzyme-substrate complex

  • Products are released

Factors Affecting Enzymes

Environmental Effects

  • Temperature

  • pH

  • Substrate concentration

  • Cause → Effect

    • High temperature → denaturation → enzyme stops working

    • pH change → alters shape → reduced activity

  • Tips

    • Use terms: active site, specificity

    • Common FRQ: explain decrease in enzyme activity

Cell Structure Foundations

Elements of Life

CHNOPS Elements

  • Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur

Bond Types

Types of Bonds

  • Covalent: strong, shared electrons

  • Ionic: transfer of electrons

  • Hydrogen: weak but important

  • Cause → Effect

    • Bond type determines molecule properties

    • Carbon bonding allows complex molecules

  • Tips

    • Carbon is the backbone of life — always safe to mention