General Biology Study Guide: Core Concepts and Skills

Introduction to General Biology

This study guide outlines the foundational concepts and skills required for success in a college-level General Biology course. It covers the major themes, molecular building blocks, cell structure, and essential biochemical processes.

Core Themes in Biology

• Characteristics of Life: All living organisms share key features such as organization, metabolism, growth, adaptation, response to stimuli, and reproduction.

• Taxonomy: The science of classifying organisms based on shared characteristics.

• Levels of Organization: Biological systems are organized from molecules up to the biosphere.

• Central Dogma: The flow of genetic information from DNA to RNA to protein.

• Evolution and Natural Selection: Evolution explains the diversity of life, with natural selection as a primary mechanism.

Scientific Methodology

• Hypothesis: A testable statement or prediction.

• Control Group: The group in an experiment that does not receive the experimental treatment.

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

Chemistry of Life

Atoms, Ions, and Molecules

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

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

• Bonds: Ionic (transfer of electrons), covalent (sharing of electrons), and hydrogen bonds (weak attractions between polar molecules).

• Properties of Water: High heat capacity, cohesion, adhesion, solvent abilities, and importance for life.

• pH: A measure of hydrogen ion concentration; scale ranges from 0 (acidic) to 14 (basic).

Biological Macromolecules

• Monomers and Polymers: Monomers are building blocks that join to form polymers.

• Four Major Classes:

  1. Carbohydrates: Monosaccharides (simple sugars) form polysaccharides (starch, glycogen, cellulose).

  2. Lipids: Glycerol and fatty acids form triglycerides, phospholipids, and steroids.

  3. Proteins: Amino acids form polypeptides and proteins; structure is determined by sequence and folding.

  4. Nucleic Acids: Nucleotides form DNA and RNA.

Functional Groups

• Hydroxyl (-OH): Found in alcohols and carbohydrates.

• Carbonyl (C=O): Found in ketones and aldehydes.

• Carboxyl (-COOH): Found in amino acids and fatty acids.

• Amino (-NH2): Found in amino acids.

• Phosphate (-PO4): Found in nucleic acids and ATP.

• Sulfhydryl (-SH): Found in some amino acids (e.g., cysteine).

Macromolecule Structures and Functions

• Carbohydrates: Energy storage (starch, glycogen), structural support (cellulose, chitin).

• Lipids: Energy storage (triglycerides), membrane structure (phospholipids), signaling (steroids).

• Proteins: Enzymes, structural components, transport, signaling, defense.

• Nucleic Acids: Store and transmit genetic information (DNA, RNA).

Protein Structure

• Primary Structure: Sequence of amino acids.

• Secondary Structure: Alpha helices and beta sheets formed by hydrogen bonding.

• Tertiary Structure: 3D folding due to side chain interactions.

• Quaternary Structure: Association of multiple polypeptide chains.

Cells and Cell Structure

Microscopy

• Light Microscopy: Uses visible light to observe cells; limited resolution.

• Electron Microscopy: Uses electron beams for higher resolution; includes transmission (TEM) and scanning (SEM) types.

Cell Types

• Prokaryotic Cells: Lack a nucleus; include bacteria and archaea.

• Eukaryotic Cells: Have a nucleus and membrane-bound organelles; include plants, animals, fungi, and protists.

Endosymbiotic Theory

• Explains the origin of mitochondria and chloroplasts in eukaryotic cells as a result of symbiosis between ancestral prokaryotes.

Cell Membranes

• Structure: Phospholipid bilayer with embedded proteins.

• Function: Regulates movement of substances in and out of the cell, communication, and cell recognition.

Biochemical Pathways and Molecule Drawing

Carbohydrates

• Glucose: Can be represented in linear or ring form (alpha or beta anomer).

• Disaccharides: Two monosaccharides joined by a glycosidic bond (e.g., maltose, sucrose, lactose).

Lipids

• Triglyceride: Formed from one glycerol and three fatty acids via ester linkage.

• Phospholipid: Glycerol backbone, two fatty acids, and a phosphate group; major component of cell membranes.

Proteins

• Amino Acids: Central carbon, amino group, carboxyl group, hydrogen, and variable R group (side chain).

• Peptide Bond: Covalent bond linking amino acids in a protein.

Nucleic Acids

• Nucleotide: Composed of a phosphate group, a five-carbon sugar (ribose or deoxyribose), and a nitrogenous base.

• DNA vs. RNA: DNA contains deoxyribose and is double-stranded; RNA contains ribose and is usually single-stranded.

Key Formulas and Equations

• pH Calculation:

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

• Generalized Dehydration Synthesis (for polymer formation):

$\text{Monomer}_1 + \text{Monomer}_2 \rightarrow \text{Polymer} + \text{H}_2\text{O}$

Table: Comparison of Macromolecules

Macromolecule	Monomer	Function	Example
Carbohydrate	Monosaccharide	Energy storage, structure	Glucose, starch, cellulose
Lipid	Glycerol & fatty acids	Energy storage, membranes	Triglyceride, phospholipid
Protein	Amino acid	Enzymes, structure, transport	Hemoglobin, actin
Nucleic Acid	Nucleotide	Genetic information	DNA, RNA

Example: Drawing Glucose

• Linear Form: Six-carbon chain with aldehyde group at one end.

• Ring Form: Hexagonal ring (pyranose) with hydroxyl groups attached.

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