General Biology: Key Concepts and Terms Study Guide

Chapter 1: Modules - Evolution and Natural Selection

Evolution and Natural Selection

Evolution is the process by which populations of organisms change over generations. Natural selection is a key mechanism of evolution, where heritable variations that enhance survival and reproduction become more common in successive generations.

• Evolution: Change in the genetic composition of a population over time.

• Natural Selection: Differential survival and reproduction of individuals due to differences in phenotype.

• Adaptation: Traits that improve an organism's ability to survive and reproduce.

• Heritable Variations: Genetic differences that can be passed to offspring.

• Artificial Selection: Human-driven selection of traits (e.g., selective breeding of crops or animals).

Example: Darwin's finches on the Galápagos Islands evolved different beak shapes to exploit different food sources.

Cell Communication and Signaling

Cells communicate through signaling pathways to coordinate activities and respond to environmental changes.

• Signaling Information: Transmission of signals (e.g., hormones, neurotransmitters) between cells.

• Example: Insulin signaling regulates blood sugar levels.

Chapter 2: Atomic Structure and Chemical Bonds

Atoms and Molecules

Atoms are the basic units of matter, composed of protons, neutrons, and electrons. Molecules are formed by atoms bonded together.

• Atom: Smallest unit of an element, consisting of a nucleus (protons and neutrons) and electrons.

• Proton: Positively charged particle in the nucleus.

• Neutron: Neutral particle in the nucleus.

• Electron: Negatively charged particle orbiting the nucleus.

• Atomic Nucleus: Center of the atom containing protons and neutrons.

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

Example: Carbon-12 and Carbon-14 are isotopes of carbon.

Chemical Bonds

Chemical bonds hold atoms together in molecules. The main types are covalent, ionic, and hydrogen bonds.

• Covalent Bond: Atoms share electrons ($A:B$).

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

• Hydrogen Bond: Weak attraction between a hydrogen atom and an electronegative atom.

• Single vs. Double Bond: Single bonds share one pair of electrons; double bonds share two pairs.

• Polar vs. Non-Polar Bond: Polar bonds have unequal sharing of electrons; non-polar bonds have equal sharing.

Example: Water ($H_2O$) has polar covalent bonds.

Chapter 3: Organic Molecules and Functional Groups

Organic Compounds

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

• Hydrocarbon: Molecule consisting only of carbon and hydrogen.

• Hydrophilic vs. Hydrophobic: Hydrophilic molecules interact with water; hydrophobic molecules do not.

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

Example: The amino group ($-NH_2$) is found in amino acids.

Macromolecules

Macromolecules are large, complex molecules essential for biological processes.

• Carbohydrates: Sugars and starches used for energy and structure.

• Lipids: Fats, oils, and steroids; important for energy storage and cell membranes.

• Proteins: Polymers of amino acids; perform a wide range of functions.

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

Example: Starch is a carbohydrate used by plants for energy storage.

Chapter 4: Cell Structure and Function

Cellular Components

Cells are the basic units of life, with specialized structures called organelles that perform distinct functions.

• Cell: Basic unit of life.

• Organelle: Specialized structure within a cell (e.g., nucleus, mitochondria).

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

• Cell Wall: Rigid outer layer found in plants, fungi, and some bacteria.

• Plasma Membrane: Semi-permeable barrier surrounding the cell.

• Cytoskeleton: Network of protein filaments for cell shape and movement.

• Endoplasmic Reticulum (ER): Rough ER (with ribosomes) synthesizes proteins; Smooth ER synthesizes lipids.

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

• Mitochondria: Site of cellular respiration and energy production.

• Chloroplast: Site of photosynthesis in plants and algae.

Example: Muscle cells contain many mitochondria to meet high energy demands.

Chapter 5: Energy and Enzymes

Energy in Biological Systems

Energy is required for all cellular processes. It exists in various forms and can be transformed from one type to another.

• Potential Energy: Stored energy due to position or structure.

• Kinetic Energy: Energy of motion.

• Redox Reactions: Chemical reactions involving the transfer of electrons.

• Coupled Reactions: Linked reactions where the energy released by one is used by another.

• Activation Energy: Minimum energy required to start a chemical reaction.

• Transition State: High-energy state during a reaction when bonds are breaking/forming.

Example: ATP hydrolysis releases energy for cellular work.

Enzymes

Enzymes are biological catalysts that speed up chemical reactions without being consumed.

• Catalyst: Substance that increases reaction rate.

• Cofactor/Coenzyme: Non-protein molecules required for enzyme activity.

• Enzyme Specificity: Each enzyme catalyzes a specific reaction.

Example: Lactase breaks down lactose in the digestive system.

Chapter 6: Metabolism and Pathways

Metabolic Pathways

Metabolism is the sum of all chemical reactions in an organism. Pathways can be anabolic (building molecules) or catabolic (breaking down molecules).

• Metabolic Pathway: Series of chemical reactions in a cell.

• Catabolic Pathway: Breaks down molecules to release energy.

• Anabolic Pathway: Builds complex molecules from simpler ones.

• Fermentation: Anaerobic process producing energy without oxygen.

• Cellular Respiration: Aerobic process converting glucose to ATP.

• Feedback Inhibition: End product inhibits pathway to regulate activity.

Example: Glycolysis is a catabolic pathway that breaks down glucose.

Chapter 7: Cell Division

Mitosis and Meiosis

Cell division is essential for growth, repair, and reproduction. Mitosis produces identical cells; meiosis produces gametes with half the chromosome number.

• Chromosome: DNA molecule with genetic information.

• Chromatid: One of two identical halves of a duplicated chromosome.

• Centromere: Region where chromatids are joined.

• Spindle Apparatus: Structure that separates chromosomes during cell division.

• Mitosis: Division of somatic cells; produces two identical daughter cells.

• Meiosis: Division of germ cells; produces four genetically unique gametes.

• Cytokinesis: Division of the cytoplasm after mitosis or meiosis.

Example: Human skin cells divide by mitosis for tissue repair.

Additional info:

• Some terms and modules referenced (e.g., "Module 5.9") may refer to specific textbook sections or course modules.

• Checklist format suggests these notes are for exam preparation and term review.