General Biology Study Guide: Life, Scientific Method, Chemistry, and Organic Molecules

Ch 1: View of Life and Scientific Method

1. Introduction to the Scientific Method and Life

The scientific method is a systematic approach used by scientists to explore observations, answer questions, and test hypotheses. Understanding the characteristics of life and the process of scientific inquiry is foundational in biology.

• Scientific Method: A series of steps including observation, hypothesis formation, experimentation, data collection, and conclusion.

• Characteristics of Life: Living things are organized, acquire materials and energy, maintain homeostasis, respond to stimuli, reproduce, grow and develop, and have adaptations.

• Emergent Properties: New properties that arise at each level of biological organization that are not present at the preceding level.

• Homeostasis: The maintenance of a stable internal environment.

• Experimental Variables: Independent variable (manipulated), dependent variable (measured), and control group (baseline for comparison).

• Placebo: A substance with no therapeutic effect, used as a control in testing new drugs.

Example: In a plant growth experiment, the amount of sunlight is the independent variable, plant height is the dependent variable, and plants not exposed to extra sunlight serve as the control group.

2. Key Scientists and Their Contributions

• Robert Hooke: Known for discovering cells using a microscope.

• Antonie van Leeuwenhoek: First to observe living microorganisms.

• Matthias Schleiden & Theodor Schwann: Proposed that plants and animals are made of cells (Cell Theory).

• Rudolf Virchow: Stated that all cells come from pre-existing cells.

• Louis Pasteur: Demonstrated that microorganisms cause fermentation and disease; developed pasteurization.

• Alexander Fleming: Discovered penicillin, the first antibiotic.

• Rosalind Franklin: Contributed to understanding DNA structure through X-ray crystallography.

• Watson and Crick: Proposed the double helix model of DNA.

• Ian Wilmut: Cloned the first mammal (Dolly the sheep).

3. Scientific Reasoning and Methods

• Deductive Reasoning: General to specific; uses general principles to predict specific results.

• Inductive Reasoning: Specific to general; uses observations to form general principles.

• Observation: Gathering information using the senses.

• Experiment: A controlled procedure to test a hypothesis.

• Scientific Law: A statement based on repeated experimental observations that describes some aspect of the world.

• Major Theories: Examples include the Cell Theory, Theory of Evolution, and Gene Theory.

Ch 2: Basic Chemistry

1. Matter and Elements

Understanding the chemical basis of life is essential in biology. Matter is composed of elements, which are substances that cannot be broken down into simpler substances by chemical means.

• Matter: Anything that has mass and takes up space.

• Elements: Pure substances consisting of only one type of atom.

• Primary Elements in Organisms: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Phosphorus (P), and Sulfur (S).

2. Atomic Structure

• Proton: Positively charged particle in the nucleus of an atom.

• Neutron: Neutral particle in the nucleus.

• Electron: Negatively charged particle orbiting the nucleus.

• Atomic Number: Number of protons in an atom.

• Atomic Mass: Sum of protons and neutrons.

• Electron Shells: Electrons occupy energy levels; the outermost shell determines chemical reactivity.

3. Chemical Bonds

• Ionic Bond: Transfer of electrons from one atom to another, resulting in oppositely charged ions.

• Covalent Bond: Sharing of electron pairs between atoms.

• Hydrogen Bond: Weak attraction between a hydrogen atom and an electronegative atom (e.g., oxygen or nitrogen).

• Bond Strength: Covalent > Ionic > Hydrogen (in biological systems).

4. Water and Its Properties

• Polarity: Water is a polar molecule, leading to hydrogen bonding.

• Cohesion and Adhesion: Water molecules stick to each other (cohesion) and to other substances (adhesion).

• High Specific Heat: Water can absorb a lot of heat before changing temperature.

• Solvent Properties: Water dissolves many substances, making it the "universal solvent."

• pH Scale: Measures hydrogen ion concentration; ranges from 0 (acidic) to 14 (basic), with 7 being neutral.

Equation:

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

Ch 3: Organic Chemistry

1. Organic Molecules and Functional Groups

Organic molecules are carbon-based compounds essential for life. They include carbohydrates, lipids, proteins, and nucleic acids.

• Hydrophobic: Repels water (e.g., oils).

• Hydrophilic: Attracts water (e.g., sugars).

• Amphipathic: Molecules with both hydrophobic and hydrophilic regions (e.g., phospholipids).

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

2. Carbohydrates

• Monosaccharide: Simple sugar (e.g., glucose).

• Disaccharide: Two monosaccharides joined (e.g., sucrose).

• Polysaccharide: Many monosaccharides linked (e.g., starch, cellulose, glycogen).

• General Formula: $\text{(CH}_2\text{O)}_n$

• Chitin: Structural polysaccharide in fungi and arthropods.

3. Lipids

• Classes of Lipids: Fats (triglycerides), phospholipids, steroids, waxes.

• Saturated Fat: No double bonds between carbon atoms; solid at room temperature.

• Unsaturated Fat: One or more double bonds; liquid at room temperature.

• Phospholipids: Major component of cell membranes; amphipathic.

• Steroids: Four fused carbon rings; cholesterol is a precursor to other steroids.

4. Proteins

• Amino Acids: Building blocks of proteins; 20 standard amino acids.

• 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.

• Enzymes: Proteins that catalyze biochemical reactions.

5. Nucleic Acids

• Nucleotide: Monomer of nucleic acids; consists of a sugar, phosphate group, and nitrogenous base.

• DNA: Double-stranded; stores genetic information.

• RNA: Single-stranded; involved in protein synthesis.

• ATP: Adenosine triphosphate; main energy currency of the cell.

Equation for ATP Hydrolysis:

$\text{ATP} + \text{H}_2\text{O} \rightarrow \text{ADP} + \text{P}_i + \text{energy}$

6. Table: Comparison of Major Organic Molecules

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

Additional info: This study guide is based on a list of questions covering foundational topics in general biology, including the scientific method, basic chemistry, and organic molecules. The explanations provided expand on the brief prompts to create a comprehensive review suitable for exam preparation.