General Biology Study Guide: Foundations and Chemistry of Life

Test 1 Study Guide: Foundations and Chemistry of Life

Overview

This study guide covers essential topics in General Biology, focusing on the chemical foundations of life, biological molecules, and basic cellular processes. Students should be familiar with definitions, examples, and the significance of each concept, as well as the ability to recognize structures and properties of major biomolecules.

Domains and Classification of Life

Domains: Bacteria, Archaea, Eukarya

• Definition: The three domains represent the broadest classification of living organisms based on genetic and cellular differences.

• Bacteria: Prokaryotic, unicellular organisms without a nucleus.

• Archaea: Prokaryotic, often extremophiles, distinct from bacteria in genetics and biochemistry.

• Eukarya: Eukaryotic organisms with membrane-bound organelles and a nucleus (includes plants, animals, fungi, protists).

Prokaryotic vs. Eukaryotic Cells

Cellular Organization

• Prokaryotic cells: Lack a nucleus and membrane-bound organelles; found in Bacteria and Archaea.

• Eukaryotic cells: Have a nucleus and membrane-bound organelles; found in Eukarya.

• Example: Escherichia coli (prokaryote), Homo sapiens (eukaryote).

Negative and Positive Feedback Regulation

Homeostasis Mechanisms

• Negative feedback: A process that reduces the output or activity of a system to maintain equilibrium (e.g., body temperature regulation).

• Positive feedback: A process that amplifies changes, moving the system away from equilibrium (e.g., blood clotting).

Biological Observations and Contributions to Biology

Scientific Method and Discovery

• Observation: Gathering data through senses or instruments.

• Hypothesis: Testable explanation for observations.

• Experimentation: Testing hypotheses under controlled conditions.

Elements, Atoms, Compounds, Molecules

Chemical Foundations

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

• Atom: Smallest unit of an element, composed of protons, neutrons, and electrons.

• Compound: Substance formed from two or more elements in fixed ratios (e.g., H2O).

• Molecule: Two or more atoms bonded together (e.g., O2).

Atomic Structure and Chemical Bonds

Atoms, Isotopes, and Bonds

• Atomic number: Number of protons in an atom.

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

• Chemical bonds: Forces holding atoms together in molecules.

• Types of bonds:

  • Covalent bonds: Sharing of electron pairs between atoms.

  • Ionic bonds: Transfer of electrons from one atom to another, resulting in charged ions.

  • Hydrogen bonds: Weak attraction between a hydrogen atom and an electronegative atom (e.g., O or N).

Chemical Properties and Interactions

Electronegativity and Polarity

• Electronegativity: Ability of an atom to attract electrons in a bond.

• Polar covalent bonds: Unequal sharing of electrons, creating partial charges.

• Nonpolar covalent bonds: Equal sharing of electrons.

Water: Structure and Properties

Emergent Properties of Water

• Cohesion: Attraction between water molecules due to hydrogen bonding.

• Adhesion: Attraction between water molecules and other substances.

• Surface tension: Measure of how difficult it is to break the surface of a liquid.

• High specific heat: Water absorbs and releases heat slowly.

• Heat of vaporization: Energy required to convert water from liquid to gas.

• Expansion upon freezing: Ice is less dense than liquid water due to hydrogen bonding.

• Solvent properties: Water dissolves many substances due to its polarity.

• Hydrophilic substances: Attracted to water; dissolve easily.

• Hydrophobic substances: Repel water; do not dissolve easily.

pH, Buffers, and Acids/Bases

Regulation of pH in Biological Systems

• pH: Measure of hydrogen ion concentration; $pH = -\log[H^+]$

• Acids: Substances that increase H+ concentration.

• Bases: Substances that decrease H+ concentration.

• Buffers: Substances that minimize changes in pH by accepting or donating H+.

Carbon Chemistry

Bonding and Functional Groups

• Valence of carbon: Carbon forms four covalent bonds, allowing for diverse molecules.

• Hydrocarbons: Molecules consisting only of carbon and hydrogen.

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

Macromolecules: Structure and Function

Polymers and Monomers

• Monomers: Small building blocks (e.g., amino acids, nucleotides, monosaccharides).

• Polymers: Large molecules made by joining monomers (e.g., proteins, nucleic acids, polysaccharides).

• Dehydration/condensation reaction: Joins monomers by removing water.

• Hydrolysis: Breaks polymers into monomers by adding water.

Major Biological Macromolecules

Types and Functions

• Carbohydrates: Energy storage and structural support; monomer is monosaccharide (e.g., glucose).

• Lipids: Energy storage, membrane structure; includes fats, phospholipids, steroids.

• Proteins: Diverse functions including catalysis (enzymes), structure, transport; monomer is amino acid.

• Nucleic acids: Information storage and transfer; DNA and RNA; monomer is nucleotide.

Protein Structure

Levels of Organization

• Primary structure: Sequence of amino acids.

• Secondary structure: Local folding (alpha helix, beta sheet) due to hydrogen bonding.

• Tertiary structure: Overall 3D shape due to interactions among side chains.

• Quaternary structure: Association of multiple polypeptide chains.

Nucleic Acids

DNA and RNA Structure

• DNA: Double helix, complementary base pairing (A-T, G-C), antiparallel strands.

• RNA: Single-stranded, various functions (messenger, transfer, ribosomal).

HTML Table: Comparison of Macromolecules

Macromolecule	Monomer	Function	Example
Carbohydrate	Monosaccharide	Energy storage, structure	Glucose, cellulose
Lipid	Fatty acid, glycerol	Energy storage, membranes	Triglyceride, phospholipid
Protein	Amino acid	Catalysis, structure, transport	Enzyme, hemoglobin
Nucleic acid	Nucleotide	Information storage, transfer	DNA, RNA

Additional info:

• Students should be able to recognize and draw basic structures of amino acids, nucleotides, and sugars.

• Be familiar with the significance of water's properties for life (e.g., temperature regulation, solvent abilities).

• Understand the role of functional groups in determining molecular properties and reactivity.