General Biology Study Notes: Key Concepts and Terms

Study Guide - Smart Notes

Tailored notes based on your materials, expanded with key definitions, examples, and context.

Chapter 1: Modules

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 individuals with advantageous traits are more likely to survive and reproduce.

Natural Selection: The process by which organisms better adapted to their environment tend to survive and produce more offspring.
Artificial Selection: The intentional breeding of organisms by humans for specific traits (e.g., dog breeds).
Heritable Variations: Genetic differences that can be passed from parents to offspring.
Signaling Information: Cells communicate using chemical signals (e.g., control of blood sugar levels).

Example: Darwin’s finches on the Galápagos Islands evolved different beak shapes due to natural selection.

Temperature Zones and Equinox/Solstice

Earth’s temperature zones are determined by latitude and the angle of sunlight. Equinoxes and solstices mark key points in Earth’s orbit, affecting day length and seasons.

Equinox: Occurs twice a year when day and night are of equal length.
Solstice: Occurs twice a year when the sun reaches its highest or lowest point in the sky at noon.

Example: The summer solstice marks the longest day of the year.

Chapter 2: Atoms and Molecules

Atomic Structure

Atoms are the basic units of matter, composed of protons, neutrons, and electrons. The atomic nucleus contains protons and neutrons, while electrons orbit the nucleus.

Proton: Positively charged particle in the nucleus.
Neutron: Neutral particle in the nucleus.
Electron: Negatively charged particle orbiting the nucleus.
Isotope: Atoms of the same element with different numbers of neutrons.

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

Electron Shells and Chemical Bonds

Electrons occupy energy levels called shells. Chemical bonds form when atoms share or transfer electrons.

Valence Electron: Electron in the outermost shell, involved in bonding.
Covalent Bond: Atoms share electrons.
Hydrogen Bond: Weak attraction between a hydrogen atom and another 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 share electrons equally.

Example: Water (H2O) has polar covalent bonds.

Chapter 3: Organic Molecules

Organic Compounds and Functional Groups

Organic molecules contain carbon and are essential for life. Functional groups are specific groups of atoms within molecules that determine their chemical properties.

Hydrophilic: Water-loving; dissolves in water.
Hydrophobic: Water-fearing; does not dissolve in water.
Amino Group: –NH2 (found in amino acids).
Carboxyl Group: –COOH (found in amino acids and fatty acids).
Phosphate Group: –PO4 (found in nucleic acids).

Example: Amino acids contain both amino and carboxyl groups.

Macromolecules

Macromolecules are large molecules essential for life, including carbohydrates, lipids, proteins, and nucleic acids.

Carbohydrates: Sugars and starches; provide energy.
Lipids: Fats and oils; store energy and make up cell membranes.
Proteins: Made of amino acids; perform various functions in cells.
Nucleic Acids: DNA and RNA; store genetic information.

Example: Glucose is a simple carbohydrate; DNA is a nucleic acid.

Chapter 4: Cell Structure

Cell Types and Organelles

Cells are the basic units of life. Eukaryotic cells have membrane-bound organelles; prokaryotic cells do not.

Cell Wall: Provides structure and protection (found in plants, fungi, and bacteria).
Plasma Membrane: Controls movement of substances in and out of the cell.
Nucleus: Contains genetic material (DNA).
Ribosome: Site of protein synthesis.
Endoplasmic Reticulum (ER): Smooth ER synthesizes lipids; rough ER synthesizes proteins.
Golgi Complex: Modifies, sorts, and packages proteins and lipids.
Mitochondria: Site of cellular respiration; produces ATP.
Cytoskeleton: Provides structural support; includes microtubules, actin filaments, and intermediate filaments.

Example: Muscle cells contain many mitochondria for energy production.

Chapter 5: Energy and Reactions

Energy in Biological Systems

Cells require energy to perform work. Energy can be stored or transferred in chemical reactions.

Potential Energy: Stored energy due to position or structure.
Kinetic Energy: Energy of motion.
Reactants and Products: Substances that start and result from a chemical reaction.
Activation Energy: Minimum energy required to start a reaction.
Coupled Reactions: Reactions that occur together, where one provides energy for the other.
ATP: Adenosine triphosphate; main energy currency of the cell.

Example: Cellular respiration converts glucose and oxygen into ATP, water, and carbon dioxide.

Chapter 6: Metabolic Pathways and Enzymes

Metabolic Pathways

Metabolic pathways are series of chemical reactions in cells, either breaking down molecules (catabolic) or building them (anabolic).

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.
Glycolysis: First step in cellular respiration; breaks down glucose.
Feedback Inhibition: End product inhibits the pathway to regulate production.

Example: Lactic acid fermentation occurs in muscle cells during intense exercise.

Enzymes

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

Active Site: Region on the enzyme where substrate binds.
Catalyst: Substance that increases reaction rate.
Competitive Inhibitor: Binds to the active site, blocking substrate.
Non-Competitive Inhibitor: Binds elsewhere, changing enzyme shape.

Example: Amylase is an enzyme that breaks down starch into sugars.

Chapter 8: 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: Structure containing DNA.
Chromatid: One half of a duplicated chromosome.
Centromere: Region where chromatids are joined.
Spindle Fibers: Help separate chromosomes during cell division.
Phases of Mitosis: Prophase, Metaphase, Anaphase, Telophase.
Cytokinesis: Division of the cytoplasm.
Meiosis: Produces four non-identical gametes.

Example: Human body cells divide by mitosis; sperm and egg cells are produced by meiosis.

Key Comparison Table: Types of Chemical Bonds

Bond Type	Definition	Strength	Example
Covalent	Atoms share electrons	Strong	Water (H2O)
Ionic	Atoms transfer electrons	Strong (in solid form)	Table salt (NaCl)
Hydrogen	Weak attraction between H and electronegative atom	Weak	Between water molecules

Key Formula: Cellular Respiration

The overall equation for cellular respiration is:

Additional info: Some terms and explanations were expanded for clarity and completeness based on standard General Biology curriculum.