Unit 1 Study Guide: Biological Macromolecules and the Chemical Basis of Life

Unit 1: Biological Macromolecules

General Theme

The central theme of this unit is the relationship between the structure of a molecule and its function in biological systems. Understanding this relationship is fundamental to the study of biology, as it underpins the behavior and roles of molecules in living organisms.

Chapter 1: Exploring Life

Characteristics and Organization of Life

• Characteristics of Life: Living organisms share key characteristics, including organization, metabolism, homeostasis, growth, reproduction, response to stimuli, and adaptation through evolution.

• Hierarchical Organization: Life is organized in a hierarchy from atoms and molecules, to cells, tissues, organs, organ systems, organisms, populations, communities, ecosystems, and the biosphere.

Chapter 2: The Chemical Basis of Life

Key Vocabulary and Concepts (Sections 1-9)

• Element: A substance that cannot be broken down into simpler substances by chemical means.

• Compound: A substance formed when two or more elements are chemically bonded together.

• Molecule: Two or more atoms held together by covalent bonds.

• Atom: The smallest unit of an element, consisting of protons, neutrons, and electrons.

• Energy: The capacity to do work or cause change.

• Potential (Positional) Energy: Stored energy due to position or structure.

• Kinetic Energy: Energy of motion.

• Electronegativity: The tendency of an atom to attract electrons in a covalent bond.

• Nonpolar and Polar Covalent Bonds: Nonpolar bonds share electrons equally; polar bonds share electrons unequally.

• Covalent and Ionic Bonds: Covalent bonds involve sharing electrons; ionic bonds involve transfer of electrons.

• Hydrogen Bonds: Weak bonds between a hydrogen atom and an electronegative atom (e.g., oxygen or nitrogen).

• van der Waals (Intermolecular) Forces: Weak attractions between molecules or parts of molecules.

• Cation: A positively charged ion.

• Anion: A negatively charged ion.

Properties of Water (Sections 10-14)

• Key Terms: Heat, temperature, specific heat, solution, solvent, solute, hydrophilic, hydrophobic, acid, base, pH.

• Water Molecule Structure: Water (H2O) is a polar molecule with a bent shape, allowing hydrogen bonding.

• Hydrogen Bonding: Water molecules form hydrogen bonds with each other, leading to unique properties.

• Emergent Properties of Water:

  • Cohesion: Water molecules stick together via hydrogen bonds.

  • Adhesion: Water molecules stick to other substances.

  • High Specific Heat: Water can absorb or release large amounts of heat with little temperature change.

  • Solvent of Life: Water dissolves many substances, facilitating chemical reactions in cells.

• Explanation: These properties arise from water's polarity and ability to form hydrogen bonds.

Chapter 3: The Molecules of Cells

Structure and Function of Biological Macromolecules (Sections 1-2)

• 3D Structure of Molecules: The three-dimensional structure of biological molecules determines their function.

• Functional Groups: Specific groups of atoms within molecules that confer characteristic chemical properties. Examples include hydroxyl (-OH), carboxyl (-COOH), amino (-NH2), and phosphate (-PO43-).

• Representation: Be able to recognize and draw each functional group.

Polymers and Monomers

• Polymers: Large molecules made by joining many smaller units (monomers) via dehydration reactions.

• Dehydration Reaction: A chemical reaction that joins monomers by removing a water molecule.

• Hydrolysis: A reaction that breaks polymers into monomers by adding water.

• Four Classes of Large Biological Molecules: Carbohydrates, lipids, proteins, nucleic acids.

Carbohydrates

• Monomers: Monosaccharides (simple sugars, e.g., glucose).

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

• Functions: Energy storage, structural support.

• Structural Differences: Differences in glycosidic linkages and branching patterns.

Lipids

• Categories: Fats, phospholipids, steroids.

• Fats: Composed of glycerol and fatty acids; function in energy storage.

• Phospholipids: Major component of cell membranes; amphipathic (hydrophilic head, hydrophobic tails).

• Steroids: Four fused carbon rings; include hormones like cholesterol.

Proteins

• Functions: Enzymatic, structural, transport, signaling, defense, storage, movement, receptor.

• Monomers: Amino acids (20 types, differing in R group).

• Levels of Structure:

  • Primary: Sequence of amino acids.

  • Secondary: Alpha helices and beta sheets (hydrogen bonding).

  • Tertiary: 3D folding due to side chain interactions.

  • Quaternary: Association of multiple polypeptides.

• Bonds and Interactions: Peptide bonds, hydrogen bonds, ionic bonds, disulfide bridges, hydrophobic interactions, van der Waals forces.

Nucleic Acids

• Monomers: Nucleotides (composed of a sugar, phosphate group, and nitrogenous base).

• Types: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).

• Structural Differences: DNA is double-stranded, contains deoxyribose; RNA is single-stranded, contains ribose.

• Functions: Storage and transmission of genetic information (DNA); protein synthesis and regulation (RNA).

Digestion & Nutrition

Digestive System and Nutrient Absorption

• Stages of Digestion: Ingestion, digestion, absorption, elimination.

• Absorption Locations: Carbohydrates, proteins, and fats are absorbed in different regions of the digestive tract (e.g., small intestine).

• Nutrition Facts Labels: Understanding the information on food labels is important for assessing nutrient intake.

Summary Table: Biological Macromolecules

Macromolecule	Monomer	Polymer	Main Functions	Examples
Carbohydrates	Monosaccharide	Polysaccharide	Energy storage, structure	Glucose, starch, cellulose
Lipids	Glycerol & Fatty Acids	Triglyceride, phospholipid, steroid	Energy storage, membranes, hormones	Fats, oils, cholesterol
Proteins	Amino acid	Polypeptide	Catalysis, structure, transport, signaling	Enzymes, hemoglobin
Nucleic Acids	Nucleotide	DNA, RNA	Genetic information, protein synthesis	DNA, RNA

Key Equations

• Dehydration Synthesis: $\text{Monomer}_1 + \text{Monomer}_2 \rightarrow \text{Polymer} + \text{H}_2\text{O}$

• Hydrolysis: $\text{Polymer} + \text{H}_2\text{O} \rightarrow \text{Monomer}_1 + \text{Monomer}_2$

• pH Calculation: $\text{pH} = -\log_{10}[\text{H}^+]$

Additional info: Some content was inferred and expanded for academic completeness, such as detailed definitions, examples, and the summary table of macromolecules.