General Biology I: Core Concepts and Laboratory Skills

General Themes in the Study of Life

Properties of Living Things

Biology is the scientific study of life, focusing on the structure, function, growth, origin, evolution, and distribution of living organisms.

• Organization: Living things are highly organized, from molecules up to the biosphere.

• Metabolism: All living organisms carry out chemical reactions to obtain and use energy.

• Homeostasis: Maintenance of a stable internal environment.

• Growth and Development: Organisms grow and develop according to specific instructions coded in their DNA.

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

• Reproduction: Ability to produce new individuals.

• Evolution: Populations evolve over generations through changes in genetic material.

Scientific Process: Involves observation, hypothesis formation, experimentation, and analysis to understand natural phenomena.

Evolution and Natural Selection: Evolution is the change in populations over time; natural selection is a key mechanism driving evolution.

Classification: Organisms are classified into domains and kingdoms based on shared characteristics.

Basic Chemistry for Biology

Atoms, Elements, and Molecules

Understanding the chemical basis of life is essential for studying biology.

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

• Elements: Pure substances consisting of only one type of atom (e.g., carbon, hydrogen, oxygen).

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

• Compounds: Substances formed by the chemical combination of two or more elements.

• Chemical Bonds: Include ionic, covalent, and hydrogen bonds.

• Water: Essential for life; properties include cohesion, adhesion, high specific heat, and solvent abilities.

Example: Water's polarity allows it to dissolve many substances, making it the universal solvent in biological systems.

Biological Chemistry

Carbon-Based Molecules and Functional Groups

Organic molecules are the foundation of life, built primarily from carbon atoms.

• Macromolecules: Large molecules essential for life, including carbohydrates, lipids, proteins, and nucleic acids.

• Carbohydrates: Sugars and starches that provide energy and structural support.

• Lipids: Fats, oils, and steroids; important for energy storage and membrane structure.

• Proteins: Polymers of amino acids; serve as enzymes, structural components, and signaling molecules.

• Nucleic Acids: DNA and RNA; store and transmit genetic information.

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

Cell Structure and Function

Prokaryotic and Eukaryotic Cells

Cells are the basic units of life, with two main types: prokaryotic and eukaryotic.

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

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

Cell Organelles and Functions:

• Nucleus: Contains genetic material (DNA).

• Ribosomes: Sites of protein synthesis.

• Endoplasmic Reticulum (ER): Synthesizes proteins and lipids.

• Golgi Apparatus: Modifies, sorts, and packages proteins and lipids.

• Mitochondria: Sites of cellular respiration and energy production.

• Chloroplasts: Sites of photosynthesis in plant cells.

• Cytoskeleton: Provides structural support and facilitates movement.

Cell Membranes: Composed of a phospholipid bilayer with embedded proteins; regulate the movement of substances in and out of the cell.

Cells and Their Membranes

Membrane Structure and Transport

The cell membrane is selectively permeable, allowing certain substances to pass while blocking others.

• Phospholipid Bilayer: Provides fluidity and flexibility to the membrane.

• Membrane Proteins: Serve as channels, carriers, receptors, and enzymes.

• Transport Mechanisms: Include passive transport (diffusion, osmosis, facilitated diffusion) and active transport (requires energy, usually ATP).

Example: The sodium-potassium pump is an active transport mechanism that maintains cellular ion balance.

Energy and Life: Metabolism

Metabolic Pathways and Enzymes

Metabolism encompasses all chemical reactions in a cell, divided into catabolic (breaking down molecules) and anabolic (building molecules) pathways.

• Enzymes: Biological catalysts that speed up chemical reactions by lowering activation energy.

• ATP (Adenosine Triphosphate): The primary energy carrier in cells.

• Energy Coupling: The use of exergonic (energy-releasing) processes to drive endergonic (energy-consuming) ones.

Equation:

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

Photosynthesis and Cellular Respiration

Energy Conversion in Cells

Cells convert energy from one form to another through photosynthesis and cellular respiration.

• Photosynthesis: Process by which plants, algae, and some bacteria convert light energy into chemical energy (glucose).

• Cellular Respiration: Process by which cells break down glucose to produce ATP.

Photosynthesis Equation:

$6\text{CO}_2 + 6\text{H}_2\text{O} + \text{light energy} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$

Cellular Respiration Equation:

$\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{ATP}$

Cell Cycle and Cell Division

Mitosis and Meiosis

Cell division is essential for growth, repair, and reproduction.

• Mitosis: Division of somatic (body) cells, resulting in two genetically identical daughter cells.

• Meiosis: Division of germ cells (gametes), resulting in four genetically unique daughter cells with half the chromosome number.

Phases of Mitosis: Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis.

Phases of Meiosis: Meiosis I and Meiosis II, each with similar stages to mitosis.

Mendelian Genetics

Inheritance Patterns

Genetics is the study of heredity and variation in organisms.

• Mendel's Laws: Law of Segregation and Law of Independent Assortment.

• Genotype vs. Phenotype: Genotype is the genetic makeup; phenotype is the observable traits.

• Alleles: Different forms of a gene.

• Dominant and Recessive Traits: Dominant alleles mask the effects of recessive alleles.

• Non-Mendelian Inheritance: Includes incomplete dominance, codominance, and polygenic traits.

Example: Human blood types (A, B, AB, O) are determined by multiple alleles and codominance.

DNA Structure and Function

Molecular Genetics

DNA (deoxyribonucleic acid) is the hereditary material in all living organisms.

• Structure: Double helix composed of nucleotides (adenine, thymine, cytosine, guanine).

• Replication: DNA makes an exact copy of itself before cell division.

• Gene Expression: DNA is transcribed into RNA, which is translated into proteins.

Central Dogma of Molecular Biology:

$\text{DNA} \rightarrow \text{RNA} \rightarrow \text{Protein}$

Recent Advances in DNA Research and Biotechnology

Applications and Techniques

Modern biology uses advanced techniques to manipulate and analyze DNA.

• Restriction Enzymes: Cut DNA at specific sequences.

• Gel Electrophoresis: Separates DNA fragments by size.

• Polymerase Chain Reaction (PCR): Amplifies specific DNA sequences.

• DNA Sequencing: Determines the order of nucleotides in DNA.

• Biotechnology: Includes genetic engineering, gene therapy, and cloning.

Example: PCR is widely used in medical diagnostics and forensic science.

Laboratory Skills and Scientific Investigation

Core Laboratory Techniques

Laboratory work is essential for understanding biological concepts and developing scientific skills.

• Microscopy: Use of microscopes to observe cells and tissues.

• Solution Preparation: Making and using solutions of known concentration.

• Diffusion and Osmosis: Studying movement of substances across membranes.

• Enzyme Activity: Measuring rates of enzyme-catalyzed reactions.

• Cellular Respiration and Photosynthesis: Investigating energy conversion in cells.

• DNA Techniques: Including extraction, electrophoresis, and fingerprinting.

Sample Table: Comparison of Prokaryotic and Eukaryotic Cells

Feature	Prokaryotic Cells	Eukaryotic Cells
Nucleus	Absent	Present
Membrane-bound Organelles	Absent	Present
Cell Size	Generally smaller (1-10 μm)	Generally larger (10-100 μm)
Examples	Bacteria, Archaea	Plants, Animals, Fungi, Protists

Additional info:

• These notes are based on a General Biology I syllabus, covering foundational topics in biology for college students.

• Laboratory skills are emphasized as a core component of the course, supporting the understanding of theoretical concepts.