General Biology Study Guide: Foundations of Life, Chemistry, Biological Molecules, and Cell Structure

Chapter 1: Introduction to Life on Earth

Characteristics and Organization of Life

This section introduces the fundamental properties that define living organisms and the hierarchical organization of biological systems.

• Biology: The scientific study of living organisms and their processes.

• 7 Characteristics of Life:

  • Order (organized structure)

  • Acquire and use energy

  • Homeostasis (maintaining internal balance)

  • Respond to stimuli

  • Growth

  • Reproduction (DNA as hereditary material)

  • Evolution (adaptation over generations)

• Levels of Organization (from smallest to largest):

  • Atoms → molecules → organelles → cells → tissues → organs → organ systems → organisms → populations → communities → ecosystems → biosphere

• Autotrophs vs. Heterotrophs:

  • Autotrophs produce their own food (e.g., plants via photosynthesis).

  • Heterotrophs obtain food by consuming other organisms (e.g., animals).

• Domains of Life: Bacteria, Archaea, Eukarya

• Binomial Nomenclature: The two-part scientific naming system for organisms (e.g., Homo sapiens).

• Scientific Method: A systematic approach to inquiry involving observation, hypothesis, experimentation, and theory development.

Example: Humans are heterotrophic, multicellular eukaryotes that maintain homeostasis and reproduce sexually.

Chapter 2: Atoms, Molecules, and Life

Basic Chemistry for Biology

This section covers the chemical principles essential for understanding biological molecules and processes.

• Atoms: The smallest units of matter, composed of protons, neutrons, and electrons.

• Subatomic Particles:

  • Protons (positive, in nucleus)

  • Neutrons (neutral, in nucleus)

  • Electrons (negative, orbit nucleus)

• Elements and Isotopes:

  • Elements are defined by the number of protons.

  • Isotopes are atoms of the same element with different numbers of neutrons.

• Chemical Bonds:

  • Ionic Bonds: Transfer of electrons (e.g., NaCl).

  • Covalent Bonds: Sharing of electrons (e.g., H2O).

  • Hydrogen Bonds: Weak attractions between polar molecules (e.g., between water molecules).

• Properties of Water:

  • Cohesion and adhesion

  • Surface tension

  • High specific heat

  • Solvent ability

  • Ice floats (less dense than liquid water)

• Acids, Bases, and Buffers:

  • Acids increase [H+], bases decrease [H+].

  • Buffers stabilize pH in biological systems.

Example: Water's high specific heat helps organisms maintain stable internal temperatures.

Equation:

$\text{pH} = -\log_{10}[\text{H}^+]$

Chapter 3: Biological Molecules

Macromolecules and Their Functions

This section explores the four major classes of biological macromolecules, their structures, and their roles in living organisms.

• Organic Molecules: Carbon-based compounds essential for life.

• Functional Groups: Specific groups of atoms (e.g., hydroxyl, carboxyl, amino, phosphate) that confer properties to molecules.

• Macromolecules:

  • Carbohydrates: Energy storage and structure (monomer: monosaccharide).

  • Lipids: Energy storage, membranes, signaling (monomer: fatty acids/glycerol).

  • Proteins: Structure, enzymes, transport (monomer: amino acids).

  • Nucleic Acids: Genetic information (monomer: nucleotide).

• Dehydration Synthesis: Joins monomers by removing water.

• Hydrolysis: Breaks polymers into monomers by adding water.

• Protein Structure:

  • Primary: Amino acid sequence

  • Secondary: Alpha helices and beta sheets

  • Tertiary: 3D folding

  • Quaternary: Multiple polypeptides

Example: Starch (storage polysaccharide in plants) and cellulose (structural polysaccharide in plants).

Chapter 4: Cell Structure and Function

Prokaryotic and Eukaryotic Cells

This section describes the structure and function of cells, the basic units of life, and compares prokaryotic and eukaryotic cell types.

• Cell: The smallest living unit.

• Plasma Membrane: Phospholipid bilayer controlling entry and exit of substances.

• Prokaryotes vs. Eukaryotes:

  • Prokaryotes: No nucleus, no membrane-bound organelles (e.g., bacteria, archaea).

  • Eukaryotes: Nucleus and membrane-bound organelles (e.g., plants, animals, fungi, protists).

• Organelles:

  • Nucleus: Contains DNA

  • Ribosomes: Protein synthesis

  • Mitochondria: "Powerhouse" of the cell, site of ATP production

  • Chloroplasts: Photosynthesis (plants and algae)

  • Endoplasmic Reticulum (ER): Protein and lipid synthesis

  • Golgi Apparatus: Modifies, sorts, and packages proteins

  • Lysosomes: Digestion

  • Vacuoles: Storage

  • Cytoskeleton: Structural support and movement

• Endomembrane System: Network of membranes involved in transport within the cell.

• Pathway of Protein Secretion: Ribosome → ER → Golgi → Vesicle → Plasma membrane

Example: Mitochondria and chloroplasts have their own DNA and ribosomes, supporting the endosymbiotic theory.

Feature	Prokaryotes	Eukaryotes
Nucleus	No	Yes
Membrane-bound organelles	No	Yes
Examples	Bacteria, Archaea	Plants, Animals, Fungi, Protists

Additional info: Compartmentalization in eukaryotic cells allows for specialized functions and greater efficiency.