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

Chapter 1: Introduction – Evolution and the Foundations of Biology

Major Themes and Levels of Organization

• Emergent Properties: New properties arise at each level in the biological hierarchy, from atoms to the biosphere.

• Levels of Organization: Atoms → Molecules → Organelles → Cells → Tissues → Organs → Organ Systems → Organisms → Populations → Communities → Ecosystems → Biosphere.

Classification of Life

• Three Domains: Bacteria, Archaea, Eukarya.

• Four Major Kingdoms in Eukarya: Protista, Fungi, Plantae, Animalia.

Scientific Inquiry and Hypothesis Testing

• Discovery Science vs. Hypothesis-Based Science: Discovery science emphasizes observation and data collection; hypothesis-based science involves proposing and testing explanations.

• Steps in Hypothesis Testing: Observation → Question → Hypothesis → Prediction → Experiment → Analysis → Conclusion.

Experimental Design

• Experimental vs. Control Groups: Experimental group receives the variable being tested; control group does not.

• Variables: Independent (manipulated), dependent (measured), and standardized/controlled variables (kept constant).

Bioinformatics, Genomics, Proteomics

• Bioinformatics: Use of computational tools to analyze biological data.

• Genomics: Study of whole genomes.

• Proteomics: Study of entire sets of proteins.

Chapter 2: The Chemical Context of Life

Atomic Structure

• Atoms: Composed of protons (positive), neutrons (neutral), and electrons (negative).

• Valence Electrons: Electrons in the outermost shell; determine chemical reactivity.

• Common Elements in Biology: C, H, O, N. Carbon (4 bonds), Hydrogen (1), Oxygen (2), Nitrogen (3).

Covalent and Ionic Bonds

• Covalent Bonds: Atoms share electrons. Can be polar (unequal sharing) or non-polar (equal sharing).

• Ionic Bonds: Transfer of electrons from one atom to another, forming ions.

• Hydrogen Bonds: Weak bonds between a hydrogen atom and an electronegative atom (e.g., O or N).

Properties of Water

• Cohesion: Water molecules stick to each other.

• Adhesion: Water molecules stick to other substances.

• Surface Tension: Measure of how difficult it is to stretch or break the surface of a liquid.

• Solvent Properties: Water dissolves many substances due to its polarity.

Solutions and Acids/Bases

• Aqueous Solution: Solution where water is the solvent.

• Acid: Substance that increases H+ concentration.

• Base: Substance that decreases H+ concentration.

• pH Scale: Measures hydrogen ion concentration; $pH = -\log[H^+]$.

• Buffers: Substances that minimize changes in pH.

Shape and Function of Molecules

• Molecular shape determines biological function and chemical reactivity.

Chapter 3: Carbon and the Molecular Diversity of Life

Organic Molecules and Functional Groups

• Four Main Categories: Carbohydrates, lipids, proteins, nucleic acids.

• Monomers and Polymers: Monomers are building blocks; polymers are chains of monomers.

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

Isomers

• Isomers: Compounds with the same formula but different structures (e.g., structural, geometric, enantiomers).

Carbohydrates

• Functions: Energy storage, structural support.

• Examples: Glucose, starch, cellulose.

Lipids

• Types: Fats, phospholipids, steroids.

• Fatty Acids: Saturated (no double bonds) vs. unsaturated (one or more double bonds).

• Phospholipids: Major component of cell membranes; amphipathic (hydrophilic head, hydrophobic tails).

Proteins

• Amino Acids: Building blocks of proteins; linked by peptide bonds.

• Levels of Structure: Primary (sequence), secondary (alpha helix, beta sheet), tertiary (3D folding), quaternary (multiple polypeptides).

• Protein Folding: Influenced by environmental factors (pH, temperature, etc.).

Nucleic Acids

• Role: Store and transmit genetic information.

• Nucleotides: Monomers of nucleic acids; DNA and RNA differ in sugar and bases.

• Pyrimidines: Cytosine, Thymine, Uracil; Purines: Adenine, Guanine.

Chapter 4: A Tour of the Cell

Microscopy

• Light Microscopes: Used for viewing live cells and tissues.

• TEM vs. SEM: Transmission Electron Microscopy (internal structures); Scanning Electron Microscopy (surface details).

Cell Structure

• Universal Components: Plasma membrane, cytoplasm, DNA, ribosomes.

• Prokaryotic vs. Eukaryotic Cells: Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have both.

Organelles and Cell Components

• Endomembrane System: Includes nuclear envelope, ER, Golgi apparatus, lysosomes, vacuoles, plasma membrane.

• Chromatin: DNA and protein complex in the nucleus.

• Ribosomes: Sites of protein synthesis.

• Plant Cell Walls: Made of cellulose.

• Extracellular Matrix (ECM): Provides structural and biochemical support to animal cells.

• Intracellular Junctions: Tight junctions, desmosomes, gap junctions (animal cells); plasmodesmata (plant cells).

• Cytoskeleton: Microtubules, microfilaments, intermediate filaments; provide structure and facilitate movement.

• Centrosome: Microtubule-organizing center; contains centrioles in animal cells.

Bond Type	Strength	Example
Covalent	Strong	H2O, CH4
Ionic	Moderate	NaCl
Hydrogen	Weak	Between water molecules

Additional info: This guide expands on the provided questions by supplying definitions, examples, and context for each topic, ensuring a comprehensive review for exam preparation.