General Biology Exam 1 Study Guide: Chapters 1–5

Important Concepts from Chapter 1: Evolution, the Themes of Biology, and Scientific Inquiry

Properties and Themes of Life

Biology is the study of living organisms and their interactions with the environment. Understanding the properties and themes of life is foundational for all biological sciences.

• Properties of Life: All living things share characteristics such as order, evolutionary adaptation, response to the environment, regulation, energy processing, growth and development, and reproduction.

• 5 Unifying Themes: Organization, information, energy and matter, interactions, and evolution.

• Hierarchy of Biological Organization: Life is organized from molecules to biosphere: molecule → organelle → cell → tissue → organ → organism → population → community → ecosystem → biosphere.

• Emergent Properties: New properties arise at each level of organization due to the arrangement and interactions of parts.

Scientific Inquiry and Experimental Design

• Scientific Method: Involves observation, hypothesis formation, experimentation, and analysis.

• Variables: In experiments, the independent variable is manipulated, while the dependent variable is measured.

Cellular and Genetic Foundations

• Prokaryotes vs. Eukaryotes: Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have both.

• DNA Function: DNA stores genetic information and directs gene expression.

• Gene Expression: The process by which information from a gene is used to synthesize a functional gene product (often a protein).

Evolution and Life on Earth

• Evolution: Explains the unity and diversity of life; all living things share a common ancestor.

• Natural Selection: Mechanism for evolution proposed by Darwin.

Important Concepts from Chapter 2: The Chemical Context of Life

Atoms, Elements, and Molecules

Understanding the chemical basis of life is essential for studying biological processes.

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

• Elements: Substances that cannot be broken down by chemical means; each element is defined by its atomic number.

• Molecules: Two or more atoms bonded together.

• Isotopes: Atoms of the same element with different numbers of neutrons; radioisotopes are unstable and decay over time.

Chemical Bonds and Interactions

• Covalent Bonds: Atoms share electrons.

• Ionic Bonds: Atoms transfer electrons, resulting in charged ions.

• Hydrogen Bonds: Weak attractions between a hydrogen atom and an electronegative atom.

• Van der Waals Interactions: Weak attractions due to transient local partial charges.

Atomic Structure and Chemical Reactions

• Energy Levels: Electrons occupy energy shells around the nucleus.

• Valence Electrons: Electrons in the outermost shell, important for chemical bonding.

• Chemical Equilibrium: The point at which the forward and reverse reactions occur at the same rate.

• Reactants and Products: Substances that start and result from a chemical reaction.

Atomic Mass and Charge

• Atomic Number: Number of protons in an atom.

• Mass Number: Sum of protons and neutrons.

• Charge: Protons (+), electrons (−), neutrons (neutral).

Important Concepts from Chapter 3: Water and Life

Properties of Water

Water is essential for life due to its unique chemical and physical properties.

• Polar Covalent Bonds: Unequal sharing of electrons creates partial charges.

• Hydrogen Bonds: Hold water molecules together, leading to cohesion and surface tension.

• Cohesion and Adhesion: Cohesion is the attraction between water molecules; adhesion is attraction to other substances.

• High Specific Heat: Water resists temperature changes due to hydrogen bonding.

• Heat of Vaporization: Amount of energy required to convert water from liquid to gas.

Water as a Solvent

• Solvent, Solute, Solution: Water dissolves many substances due to its polarity.

• Aqueous Solutions: Solutions where water is the solvent.

Acids, Bases, and pH

• Acids: Substances that increase H+ concentration.

• Bases: Substances that decrease H+ concentration.

• pH Scale: Measures H+ concentration; $\text{pH} = -\log[\text{H}^+]$

• Buffers: Substances that minimize changes in pH.

Hydrophilic and Hydrophobic Properties

• Hydrophilic: Substances that interact with water.

• Hydrophobic: Substances that repel water.

Important Concepts from Chapter 4: Carbon and the Molecular Diversity of Life

Properties of Carbon

Carbon is the backbone of biological molecules due to its ability to form four covalent bonds.

• Versatility: Carbon can form chains, rings, and complex structures.

• Isomers: Molecules with the same formula but different structures (structural, cis-trans, enantiomers).

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

ATP: The Energy Currency

• Adenosine Triphosphate (ATP): Stores and transfers energy in cells.

Important Concepts from Chapter 5: The Structure and Function of Large Biological Molecules

Macromolecules and Polymers

Large biological molecules are essential for structure and function in living organisms.

• Monomers and Polymers: Monomers are building blocks; polymers are chains of monomers.

• Carbohydrates: Include monosaccharides, disaccharides, and polysaccharides; provide energy and structural support.

• Starch, Glycogen, Cellulose: Polysaccharides with different functions and structures.

• Lipids: Fats, oils, and steroids; hydrophobic and used for energy storage and membranes.

• Saturated vs. Unsaturated Fatty Acids: Saturated have no double bonds; unsaturated have one or more double bonds.

• Phospholipids: Major component of cell membranes; amphipathic nature.

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

• Levels of Protein Structure: Primary, secondary, tertiary, and quaternary.

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

• DNA/RNA Structure: Double helix for DNA; single-stranded for RNA.

Examples and Applications

• Enzymes: Biological catalysts that speed up chemical reactions.

• Genetic Information: DNA encodes instructions for building proteins.