Chapter 1: Themes in the Study of Life

Phylogenetic Maps and Common Ancestors

Phylogenetic maps (or trees) illustrate evolutionary relationships among organisms. The most recent common ancestor is the point where two lineages diverge.

• Phylogenetic Tree: Diagram showing evolutionary relationships.

• Most Recent Common Ancestor: The node where two groups share a lineage before diverging.

• Application: Used to trace evolutionary history and classify organisms.

Deductive vs. Inductive Reasoning

Scientific inquiry uses both deductive and inductive reasoning to form hypotheses and interpret data.

• Deductive Reasoning: General principles lead to specific predictions (e.g., "If all cells have DNA, then this cell should have DNA").

• Inductive Reasoning: Specific observations lead to general conclusions (e.g., "All observed cells have DNA, so all cells have DNA").

• Hypothesis: A testable statement explaining an observation.

• Qualitative Data: Descriptive, non-numerical information (e.g., color, shape).

• Quantitative Data: Numerical measurements (e.g., length, mass).

DNA, RNA, Genes, and Genome

Genetic material is central to life, governing inheritance and gene expression.

• DNA (Deoxyribonucleic Acid): Stores genetic information.

• RNA (Ribonucleic Acid): Transfers genetic information and helps synthesize proteins.

• Gene: Segment of DNA coding for a protein or functional RNA.

• Genome: Complete set of genetic material in an organism.

• Nucleotides: Building blocks of DNA and RNA, composed of a sugar, phosphate, and nitrogenous base.

• Gene Expression (Central Dogma): DNA → RNA → Protein

Equation:

Domains and Taxonomy

Taxonomy classifies organisms into hierarchical groups. The three domains are the broadest classification.

• Domains: Bacteria, Archaea, Eukarya

• Taxonomy: Science of classification; includes domain, kingdom, phylum, class, order, family, genus, species.

Eukaryotic vs. Prokaryotic Cells

Cells are classified as prokaryotic or eukaryotic based on structure.

• Prokaryotic Cells: Lack nucleus and membrane-bound organelles (e.g., Bacteria, Archaea).

• Eukaryotic Cells: Have nucleus and membrane-bound organelles (e.g., plants, animals, fungi, protists).

Theories and Evolution

A scientific theory is a well-supported explanation. The theory of evolution explains the diversity of life.

• Theory: Broad explanation supported by evidence.

• Theory of Evolution: All species change over time through natural selection.

• Natural Selection: Process where organisms better adapted to their environment survive and reproduce.

Chapter 22: Descent with Modification

Contributions of Darwin, Wallace, and Cuvier

Key scientists contributed to evolutionary theory.

• Charles Darwin: Proposed natural selection as the mechanism of evolution.

• Alfred Russel Wallace: Independently conceived natural selection; co-published with Darwin.

• Georges Cuvier: Developed paleontology; advocated catastrophism (extinctions due to sudden events).

Homologous and Vestigial Structures

Structures provide evidence for evolution.

• Homologous Structures: Similar anatomy due to shared ancestry (e.g., vertebrate limbs).

• Vestigial Structures: Remnants of features that served a function in ancestors (e.g., human appendix).

Evidence Supporting Evolution

Multiple lines of evidence support the theory of evolution.

• Fossil Record: Shows changes in organisms over time.

• Comparative Anatomy: Homologous and vestigial structures.

• Molecular Biology: DNA and protein similarities.

• Biogeography: Geographic distribution of species.

Strata Analysis and Common Ancestors

Strata (layers of rock) help determine the age of fossils and evolutionary relationships.

• Strata: Layers of sedimentary rock; older layers are deeper.

• Most Recent Common Ancestor: Located by comparing fossil positions in strata.

Chapter 2: The Chemical Context of Life

Elements, Compounds, and the Periodic Table

Life is composed of a few essential elements, organized in the periodic table.

• Element: Pure substance consisting of one type of atom (e.g., carbon).

• Compound: Substance formed from two or more elements (e.g., water).

• Essential Elements: About 96% of living matter is made of C, H, O, N.

Subatomic Particles and Atomic Structure

Atoms are made of protons, neutrons, and electrons.

• Proton: Positive charge; found in nucleus.

• Neutron: No charge; found in nucleus.

• Electron: Negative charge; orbits nucleus.

• Atomic Number: Number of protons.

• Atomic Mass: Sum of protons and neutrons.

Equation:

Electron Shells and Electronegativity

Electron arrangement determines chemical properties.

• Shells: Energy levels where electrons reside.

• Valence Electrons: Electrons in the outermost shell; determine reactivity.

• Valence Shell: Outermost electron shell.

• Electronegativity: Atom's ability to attract electrons.

Calculating Mass Number and Periodic Table Interpretation

Mass number is used to identify isotopes and atomic structure.

• Mass Number: Total number of protons and neutrons.

• Periodic Table: Organizes elements by atomic number and properties.

Chemical Bonds

Atoms form bonds to achieve stable electron configurations.

• Single Bond: One pair of shared electrons.

• Double Bond: Two pairs of shared electrons.

• Nonpolar Covalent Bond: Electrons shared equally.

• Polar Covalent Bond: Electrons shared unequally.

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

• Ionic Bond: Transfer of electrons creates charged ions.

Isotopes

Isotopes are atoms of the same element with different numbers of neutrons.

• Isotope: Same number of protons, different number of neutrons.

• Application: Used in radiometric dating and medical imaging.

Chemical Reactions

Chemical reactions rearrange atoms to form new substances.

• Reactants: Starting substances.

• Products: Resulting substances.

• Example: Photosynthesis, cellular respiration.

Equation:

Chapter 6: Tour of the Cell

Prokaryotic vs. Eukaryotic Cell Features

Cell structure distinguishes prokaryotes from eukaryotes.

• Prokaryotes: No nucleus, no membrane-bound organelles, small size.

• Eukaryotes: Nucleus, membrane-bound organelles, larger size.

Animal vs. Plant Cell Features

Animal and plant cells share many features but also have unique structures.

• Animal Cells: No cell wall, have lysosomes, centrioles.

• Plant Cells: Cell wall, chloroplasts, central vacuole.

Organelles and Their Functions

Organelles perform specialized functions within cells.

• Nucleus: Contains genetic material.

• Mitochondria: Site of cellular respiration.

• Chloroplast: Site of photosynthesis (plants).

• Endoplasmic Reticulum (ER): Protein and lipid synthesis.

• Golgi Apparatus: Modifies and packages proteins.

• Lysosome: Digests cellular waste (animals).

• Vacuole: Storage and structure (plants).

Endomembrane System

The endomembrane system coordinates synthesis, transport, and processing of cellular materials.

• Components: Nuclear envelope, ER, Golgi apparatus, lysosomes, vesicles, plasma membrane.

• Function: Synthesis and transport of proteins and lipids.

Organelle Dysfunction Examples

Malfunctioning organelles can cause disease.

• Lysosomal Storage Diseases: E.g., Tay-Sachs disease.

• Mitochondrial Disorders: Affect energy production.

Extracellular Matrix (ECM) and Cell Junctions

Cells interact with their environment and each other via ECM and junctions.

• ECM: Network of proteins and carbohydrates outside cells; provides support and signaling.

• Cell Junctions: Structures connecting cells.

• Plasmodesmata: Channels between plant cells.

• Gap Junctions: Channels between animal cells for communication.