General Biology: Foundations, Chemistry of Life, and Biological Macromolecules

Chapter 1: Evolution, Themes of Biology, and Scientific Inquiry

Unifying Theory of Biology

The theory of evolution is the central unifying concept in biology, explaining both the unity and diversity of life. It describes how organisms change over time through modification and natural selection.

• Evolution: Descent with modification accounts for life's unity and diversity.

• Environments enable the growth, reproduction, and survival of some individuals over others.

Characteristics of Life

All living organisms share certain fundamental characteristics that distinguish them from non-living matter.

• Order: Highly organized structures.

• Evolutionary Adaptation: Populations evolve over generations.

• Regulation: Homeostasis and internal balance.

• Response to Environment: Reacting to stimuli.

• Growth and Development: Controlled by genetic information.

• Energy Processing: Use of energy to power activities.

• Emergent Properties: New properties arise at each level of organization.

Organization of Life

Biological organization ranges from molecules to the entire biosphere, with each level exhibiting emergent properties.

• Biosphere

• Ecosystems

• Communities

• Populations

• Organisms

• Organs & Organ Systems

• Tissues

• Cells

• Organelles

• Molecules

Domains of Life

• Bacteria: Prokaryotic, single-celled, DNA, found in every habitat.

• Archaea: Prokaryotic, single-celled, RNA, extreme environments.

• Eukarya: Eukaryotic (plants, animals, fungi, protists), have nuclei, multicellular or unicellular.

Scientific Inquiry Steps

• Forming & Testing Hypotheses

• Social Benefits/Outcomes

• Exploration/Discovery

Chapter 2: The Chemical Context of Life

Basic Chemistry Concepts

• Matter: Anything that takes up space and has mass.

• Atom: Smallest unit of matter retaining element properties.

• Element: Substance made of one type of atom.

• Molecule: Two or more atoms chemically bonded.

• Compound: Substance with two or more elements in a fixed ratio.

Atomic Structure

• Atomic Number: Number of protons in nucleus.

• Mass Number: Protons + neutrons.

• Isotopes: Atoms with same number of protons, different neutrons.

• Electrons: Negligible mass, determine chemical reactivity.

Chemical Bonds

• Ionic Bonds: Electrons transferred (e.g., NaCl). Cation loses electron (positive), anion gains (negative).

• Covalent Bonds: Electrons shared (e.g., H2, CO2).

• Polar Covalent: Unequal sharing (e.g., H2O).

• Nonpolar Covalent: Equal sharing (e.g., O2).

• Electronegativity: Atom's attraction for electrons in a bond.

• Hydrogen Bonds: Weak bonds between hydrogen and electronegative atoms (e.g., O, N).

Chapter 3: Water and Its Emergent Properties for Life

Properties of Water

• Cohesion: Water molecules stick together (surface tension, capillary action).

• Adhesion: Water molecules stick to other substances.

• High Specific Heat: Water resists temperature change.

• High Heat of Vaporization: Large amount of energy needed to vaporize water.

• Solvent of Life: Dissolves many substances (hydrophilic vs. hydrophobic).

• Expansion Upon Freezing: Ice is less dense than liquid water.

Acids, Bases, and pH

• Acid: Increases H+ concentration in solution.

• Base: Reduces H+ concentration.

• pH Scale: $pH = -\log[H^+]$

• Buffers: Substances that minimize pH changes.

Chapter 4: Carbon and Molecular Diversity of Life

Origin of Organic Molecules

• Miller-Urey Experiment: Simulated early Earth, showed organic molecules could form abiotically.

Carbon's Versatility

• Forms four covalent bonds, allowing for diverse molecules.

• Can form chains, rings, branching structures.

Isomers

• Structural Isomers: Differ in covalent arrangement.

• Cis-Trans Isomers: Differ in arrangement around double bonds.

• Enantiomers: Mirror images, differ in spatial arrangement.

Functional Groups

Group	Structure	Properties/Examples
Hydroxyl	-OH	Alcohols, polar, forms H-bonds
Carbonyl	>C=O	Aldehydes, ketones, sugars
Carboxyl	-COOH	Acids, donates H+
Amino	-NH2	Amines, acts as base
Sulfhydryl	-SH	Thiols, forms disulfide bonds
Phosphate	-OPO32-	Organic phosphates, ATP
Methyl	-CH3	Nonpolar, affects gene expression

Chapter 5: The Structure and Function of Large Biological Molecules

Macromolecules Overview

• Condensation (Dehydration) Synthesis: Monomers join to form polymers, releasing water.

• Hydrolysis: Polymers broken down into monomers, adding water.

Carbohydrates

• Elements: C, H, O (1:2:1 ratio).

• Monosaccharides: Simple sugars (e.g., glucose, fructose).

• Disaccharides: Two monosaccharides (e.g., sucrose, lactose).

• Polysaccharides: Many monosaccharides (e.g., starch, cellulose, glycogen).

• Glycosidic Linkage: Covalent bond joining monosaccharides.

• Storage Polysaccharides: Starch (plants), glycogen (animals).

• Structural Polysaccharides: Cellulose (plants), chitin (fungi, arthropods).

Lipids

• Elements: C, H, O.

• Hydrophobic, not true polymers.

• Fats: Glycerol + 3 fatty acids (triglyceride), joined by ester linkage.

• Saturated Fats: No double bonds, solid at room temperature.

• Unsaturated Fats: One or more double bonds, liquid at room temperature.

• Phospholipids: Glycerol + 2 fatty acids + phosphate group; form cell membranes (bilayer).

• Steroids: Four fused carbon rings (e.g., cholesterol, hormones).

Proteins

• Elements: C, H, O, N (sometimes S).

• Amino Acids: Monomers, 20 types, central alpha carbon.

• Peptide Bond: Covalent bond between amino acids.

• Levels of Structure:

  • Primary: Sequence of amino acids.

  • Secondary: Alpha helix, beta sheet (hydrogen bonds).

  • Tertiary: 3D folding (side chain interactions).

  • Quaternary: Multiple polypeptides (e.g., hemoglobin).

• Denaturation: Loss of structure due to heat, pH, chemicals.

• Chaperonins: Proteins that assist folding.

Nucleic Acids

• DNA: Deoxyribonucleic acid, double helix, stores genetic information.

• RNA: Ribonucleic acid, single-stranded, involved in protein synthesis.

• Nucleotide: Monomer (phosphate, sugar, nitrogenous base).

• Purines: Adenine (A), Guanine (G) – double ring.

• Pyrimidines: Cytosine (C), Thymine (T), Uracil (U) – single ring.

• Phosphodiester Bond: Links nucleotides in DNA/RNA.

Biological Tests

Test	Detects	Result
Benedict's	Simple sugars, monosaccharides	Orange/red color change
Lugol's Iodine	Starch, polysaccharides	Dark purple/black
Sudan IV	Lipids, fats/oils	Red solution, floats
Biuret	Proteins, peptide bonds	Purple/violet

Practice Test Notes

• Structure = function in biology.

• Viruses are not living (not in 3 domains of life).

• C, H, O, N are most abundant elements in living organisms.

• Unpaired electrons in valence shells form covalent bonds.

• Water forms hydrogen bonds, leading to its unique properties.

• Hydrogen bonds: H covalently bonded to highly electronegative atom (N, O).

• Electrons in neutral atom: protons = electrons.

• Saturated fatty acid: no double bonds between C atoms.

• Unsaturated fatty acid: at least one double bond between C atoms.

• Electrons have negligible mass.