General Biology I: Core Concepts and Study Guide

Ch. 1: Introduction to Biology

What is Life? Characteristics of Living Organisms

Biology is the study of living organisms and their interactions with the environment. To be considered alive, an entity must exhibit certain characteristics.

• Order: Living things are organized and structured.

• Response to Stimuli: Ability to respond to environmental changes.

• Reproduction: Capable of producing offspring.

• Growth and Development: Organisms grow and develop following specific instructions coded in their genes.

• Regulation: Maintain internal balance (homeostasis).

• Energy Processing: Use energy for metabolic processes.

• Evolutionary Adaptation: Populations evolve over generations.

• Example: SARS-CoV-2 is non-living because it cannot reproduce or carry out metabolism independently.

Unicellular vs. Multicellular Organisms

• Unicellular: Consist of a single cell (e.g., Escherichia coli).

• Multicellular: Composed of many cells (e.g., humans, plants).

Cell Structure and Universal Features

• Cell: The basic unit of life.

• Universal Structures: All cells have a plasma membrane, cytoplasm, DNA, and ribosomes.

• Function: These structures are essential for protection, genetic information storage, and protein synthesis.

Prokaryotes vs. Eukaryotes

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

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

• Key Difference: Presence of a nucleus and complexity of internal structures.

Animal vs. Plant Cells

• Animal Cells: Lack cell walls, have centrioles, and small vacuoles.

• Plant Cells: Have cell walls, chloroplasts, and large central vacuoles.

Three Domains of Life

• Bacteria: Prokaryotic, unicellular, diverse environments.

• Archaea: Prokaryotic, often extremophiles.

• Eukarya: Eukaryotic, includes plants, animals, fungi, protists.

Charles Darwin and Evolution

• Charles Darwin: Proposed the theory of evolution by natural selection.

• Evolution: Change in populations over time due to heritable traits.

• Homology: Similarity due to shared ancestry.

Homeostasis

• Definition: Maintenance of a stable internal environment.

• Example: Regulation of body temperature in mammals.

Hierarchy of Life

• Levels: Atom → Molecule → Organelle → Cell → Tissue → Organ → Organ System → Organism → Population → Community → Ecosystem → Biosphere

Scientific Method

• Steps: Observation, hypothesis, experiment, data collection, analysis, conclusion.

• Variables: Independent (manipulated), dependent (measured), controlled (kept constant).

• Graph Interpretation: Ability to read and interpret data representations.

Emergent Properties

• Definition: New properties that arise at each level of biological organization.

• Example: Life emerges from the interaction of non-living molecules.

Ch. 2: Chemistry of Life

Atoms, Molecules, and Subatomic Particles

• Atom: Smallest unit of matter.

• Molecule: Two or more atoms bonded together.

• Subatomic Particles: Protons (positive), neutrons (neutral), electrons (negative).

• Atomic Number: Number of protons.

• Atomic Mass: Number of protons + neutrons.

Essential Elements

• Major Elements: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Phosphorus (P), Sulfur (S).

• These elements make up the majority of living matter.

Isotopes

• Definition: Atoms of the same element with different numbers of neutrons.

• Application: Radioactive isotopes used in medical imaging.

Electrons and Chemical Bonds

• Electrons: Determine chemical reactivity and bonding.

• Types of Bonds:

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

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

  • Polar Covalent: Unequal sharing (e.g., H2O).

  • Nonpolar Covalent: Equal sharing (e.g., O2).

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

Polarity and Water

• Polar Molecules: Hydrophilic, dissolve in water (e.g., sugars).

• Nonpolar Molecules: Hydrophobic, do not dissolve in water (e.g., oils).

Ch. 3: Biological Macromolecules

The Four Biomolecules

• Carbohydrates: Monomer: monosaccharide; Polymer: polysaccharide. Function: energy storage (e.g., starch in plants, glycogen in animals).

• Lipids: Not true polymers. Types: fats, phospholipids, steroids. Function: energy storage, membrane structure, hormones.

• Proteins: Monomer: amino acid; Polymer: polypeptide. Function: enzymes, structure, transport, signaling.

• Nucleic Acids: Monomer: nucleotide; Polymer: DNA/RNA. Function: genetic information storage and transfer.

Monomers and Polymers

• Monomer: Small building block molecule.

• Polymer: Large molecule made of repeating monomers.

• Polymerization: Dehydration synthesis joins monomers; hydrolysis breaks polymers.

Isomers and Functional Groups

• Isomer: Molecules with the same formula but different structures.

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

Proteins: Structure and Function

• Primary Structure: Sequence of amino acids.

• Secondary Structure: Alpha helices and beta sheets.

• Tertiary Structure: 3D folding.

• Quaternary Structure: Multiple polypeptides.

• Denaturation: Loss of structure due to heat, pH, or chemicals.

• Examples: Enzymes (catalysts), hormones (insulin), structural proteins (keratin).

Polysaccharides

• Cellulose: Plant cell walls.

• Starch: Plant energy storage.

• Glycogen: Animal energy storage.

Lipids: Fats, Phospholipids, Steroids

• Fats: Triglycerides; saturated (no double bonds) vs. unsaturated (double bonds).

• Phospholipids: Major component of cell membranes.

• Steroids: Hormones like estrogen and testosterone.

DNA and RNA

• DNA: Double helix, stores genetic information.

• RNA: Single-stranded, various roles in protein synthesis.

• Central Dogma: DNA → RNA → Protein

Ch. 4: Cell Structure and Function

Prokaryotic vs. Eukaryotic Cells

• Prokaryotic: No nucleus, simple structure.

• Eukaryotic: Nucleus, complex organelles.

• Common Features: Plasma membrane, cytoplasm, ribosomes, DNA.

Organelles in Eukaryotic Cells

• Nucleus: Contains DNA.

• Mitochondria: ATP production.

• Chloroplasts: Photosynthesis (plants).

• Endoplasmic Reticulum: Protein and lipid synthesis.

• Golgi Apparatus: Modifies and ships proteins.

• Lysosomes: Digestion.

• Vacuoles: Storage (large in plants).

Animal vs. Plant Eukaryotic Cells

• Animal Cells: No cell wall, small vacuoles, centrioles.

• Plant Cells: Cell wall, chloroplasts, large central vacuole.

Cytoskeleton

• Microfilaments: Actin, cell movement.

• Intermediate Filaments: Structural support.

• Microtubules: Tubulin, cell shape, cilia, flagella.

Cell Wall Comparison

Organism	Cell Wall Composition
Plants	Cellulose
Fungi	Chitin
Bacteria	Peptidoglycan

Symbiosis and Endosymbiosis Theory

• Symbiosis: Close relationship between different species.

• Endosymbiosis Theory: Eukaryotic organelles (mitochondria, chloroplasts) originated from prokaryotes engulfed by ancestral eukaryotes.