Chapter 1: Introduction to Biology & The Tree of Life

What Makes Something Alive?

This topic introduces the basic criteria that define life and explores how living things may have evolved from non-living materials. Understanding these concepts is foundational for all further study in biology.

• Cellular Organization: All living things are composed of one or more cells, which are the basic units of life.

• Metabolism: Living organisms carry out chemical reactions to obtain and use energy.

• Growth and Development: Living things grow and develop according to specific instructions coded in their DNA.

• Response to Stimuli: Organisms respond to environmental changes.

• Reproduction: Living things reproduce, passing genetic information to offspring.

• Evolution: Populations of organisms evolve over time through changes in genetic material.

• Example: Escherichia coli (E. coli) is a single-celled organism that exhibits all characteristics of life.

Chapter 2: The Chemistry of Life

Atoms, Bonds, and Water

This chapter covers the chemical principles that underlie biological processes, including atomic structure, chemical bonding, and the properties of water.

• Atoms & Bonds: Atoms are the smallest units of matter. Chemical bonds (covalent, ionic, hydrogen) hold atoms together in molecules.

  • Covalent bonds: Atoms share electrons ().

  • Ionic bonds: Atoms transfer electrons, forming charged ions ().

  • Hydrogen bonds: Weak attractions between polar molecules, important in water and DNA.

• The Power of Water: Water is a polar molecule, making it an excellent solvent. Its hydrogen bonding gives it unique properties such as high specific heat and cohesion.

• Acids & Bases: Acids donate protons (), bases accept protons. The pH scale measures acidity ().

• Carbon's Role: Carbon forms the backbone of organic molecules due to its ability to form four covalent bonds.

• Example: Glucose () is an organic molecule built from carbon, hydrogen, and oxygen.

Chapter 3: Proteins—The Workhorses of the Cell

Structure and Function of Proteins

Proteins are essential macromolecules that perform a wide variety of functions in cells, from catalyzing reactions to providing structural support.

• Amino Acids & Structure: Proteins are polymers of amino acids. Each amino acid has a central carbon, an amino group (), a carboxyl group (), and a variable side chain (R group).

• From Chain to 3D Shape: Protein structure is organized into four levels:

  • Primary: Sequence of amino acids.

  • Secondary: Local folding (alpha helices, beta sheets).

  • Tertiary: Overall 3D shape.

  • Quaternary: Multiple polypeptide chains.

• Folding & Function: The specific shape of a protein determines its function. Misfolded proteins can lead to diseases.

• Example: Hemoglobin is a quaternary protein that carries oxygen in blood.

Chapter 6: Lipids & Membranes—The Cell's Boundary

Structure and Function of Membranes

Cell membranes separate the internal environment from the external environment and regulate the movement of substances in and out of the cell.

• Lipid Structure: Lipids are hydrophobic molecules. Membranes are primarily composed of phospholipids, which have hydrophilic heads and hydrophobic tails.

• Building the Bilayer: Phospholipids spontaneously form bilayers in water, creating a flexible barrier.

• Fluidity & Permeability: Membrane fluidity is affected by lipid composition and cholesterol. Permeability determines which substances can cross the membrane.

• Transport Across the Membrane:

  • Passive transport: Movement without energy input (diffusion, osmosis).

  • Active transport: Movement against a gradient, requiring energy (often ATP).

• Example: Oxygen diffuses passively across cell membranes, while sodium ions are actively transported.

Chapter 7: Inside the Cell

Cell Types and Organelles

This chapter explores the differences between prokaryotic and eukaryotic cells and describes the functions of key organelles.

• Prokaryotes vs. Eukaryotes:

  • Prokaryotes: No nucleus, smaller, simpler (e.g., bacteria).

  • Eukaryotes: Nucleus present, larger, complex organelles (e.g., plants, animals).

• Organelles & Compartments: Eukaryotic cells contain membrane-bound organelles such as the nucleus, mitochondria, and endoplasmic reticulum, which compartmentalize cellular functions.

• Example: The mitochondrion is the site of cellular respiration, producing ATP.

Chapter 8: Energy & Enzymes

Cellular Energy and Enzyme Function

This chapter explains how cells manage energy and use enzymes to control chemical reactions.

• Energy Basics:

  • Kinetic energy: Energy of motion.

  • Potential energy: Stored energy.

  • Exergonic reaction: Releases energy ().

  • Endergonic reaction: Absorbs energy ().

• Enzymes as Catalysts: Enzymes lower the activation energy () of reactions, increasing reaction rates.

  • Graph: Reaction rate vs. activation energy (drawn in class).

• Factors Affecting Enzymes: Temperature, pH, and the presence of inhibitors or activators can affect enzyme activity.

  • Competitive inhibition: Inhibitor binds to active site.

  • Allosteric inhibition: Inhibitor binds elsewhere, changing enzyme shape.

• Energetic Coupling: Cells use ATP to link exergonic and endergonic reactions, allowing energy transfer.

  • ATP hydrolysis:

• Example: The enzyme hexokinase catalyzes the phosphorylation of glucose in glycolysis.

Additional info: Academic context and definitions have been expanded for clarity and completeness. Tables have been recreated to compare transport types and cell features. Equations are provided in LaTeX format for key chemical and biological processes.