Chapter 5: The Structure and Function of Large Biological Molecules

Macromolecules: Types and Importance

Macromolecules are large, complex molecules essential for life, including carbohydrates, lipids, proteins, and nucleic acids. They perform a variety of structural and functional roles in cells.

• Definition: A macromolecule is a large molecule formed by the polymerization of smaller subunits called monomers.

• Polymer: A polymer is a long molecule consisting of many similar or identical building blocks linked by covalent bonds.

• Monomers: Examples include monosaccharides (carbohydrates), amino acids (proteins), nucleotides (nucleic acids), and fatty acids/glycerol (lipids).

• Dehydration Synthesis: The process by which monomers are joined together, releasing water.

• Hydrolysis: The process by which polymers are broken down into monomers, consuming water.

Carbohydrates

Carbohydrates are sugars and their polymers, serving as energy sources and structural components.

• Functions: Energy storage (e.g., starch, glycogen), structural support (e.g., cellulose, chitin).

• Types: Monosaccharides, disaccharides, polysaccharides.

Lipids

Lipids are hydrophobic molecules, including fats, phospholipids, and steroids.

• Triglyceride Structure: Composed of three fatty acids linked to a glycerol molecule.

• Phospholipids: Major component of cell membranes; have hydrophilic heads and hydrophobic tails.

• Function: Energy storage, membrane structure, signaling.

Proteins

Proteins are polymers of amino acids that perform a vast array of cellular functions.

• Structure: Primary, secondary, tertiary, and quaternary levels.

• Function: Enzymes, structural support, transport, signaling.

• Shape and Function: The shape of a protein determines its function; changes in shape can affect activity.

Nucleic Acids

Nucleic acids store and transmit genetic information.

• Types: DNA and RNA.

• Structure: Polymers of nucleotides; DNA is double-stranded, RNA is single-stranded.

• Comparison: DNA stores genetic information; RNA is involved in protein synthesis.

Chapter 6: Tour of the Cell

Cell Theory and Cell Types

The cell theory states that all living things are composed of cells, which are the basic units of life.

• Plasma Membrane: Separates the cell from its environment; controls movement of substances.

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

Plant and Animal Cells

Plant and animal cells share many organelles but also have distinct structures.

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

• Animal Cell Organelles: Lysosomes, centrioles.

Cell Structures and Functions

• Nucleus: Contains genetic material; controls cell activities.

• Endomembrane System: Includes the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, and vesicles.

• Mitochondria and Chloroplasts: Sites of cellular respiration and photosynthesis, respectively.

• Cytoskeleton: Microfilaments, intermediate filaments, microtubules; provides structure and facilitates movement.

Cell Surface and Junctions

• Cilia and Flagella: Structures for movement.

• Extracellular Matrix: Network outside animal cells; provides support.

• Cell Junctions: Tight junctions, anchoring junctions, gap junctions; facilitate communication and adhesion.

Chapter 7: Membrane Structure and Function

Cell Membrane Structure

Cell membranes are composed of a phospholipid bilayer with embedded proteins, providing selective permeability.

• Phospholipid Bilayer: Hydrophilic heads face outward; hydrophobic tails face inward.

• Proteins: Integral and peripheral; involved in transport, signaling, and structural support.

Membrane Transport

• Passive Transport: Movement of substances down their concentration gradient (diffusion, osmosis).

• Osmosis: Diffusion of water across a membrane.

• Hypertonic, Hypotonic, Isotonic Solutions: Affect water movement in cells.

• Facilitated Diffusion: Transport proteins help move substances across membranes.

• Active Transport: Movement against concentration gradient; requires energy.

• Endocytosis and Exocytosis: Bulk transport of materials into and out of cells.

Chapter 8: Introduction to Metabolism

Energy and Thermodynamics

Metabolism involves all chemical reactions in cells, governed by the laws of thermodynamics.

• Kinetic Energy: Energy of motion.

• Potential Energy: Stored energy.

• Chemical Energy: Energy stored in chemical bonds.

• First Law of Thermodynamics: Energy cannot be created or destroyed.

• Second Law of Thermodynamics: Entropy (disorder) increases in isolated systems.

ATP and Enzymes

• ATP: Main energy currency of the cell; energy released by hydrolysis.

• ATP Cycle:

• Enzymes: Biological catalysts that speed up reactions by lowering activation energy.

Chapter 9: Cellular Respiration and Fermentation

Overview of Cellular Respiration

Cellular respiration is the process by which cells extract energy from glucose.

• General Equation:

• Stages: Glycolysis, Krebs cycle (citric acid cycle), electron transport chain.

• ATP Production: Most ATP is produced in the electron transport chain.

• NADH and FADH2: Electron carriers in cellular respiration.

Fermentation

• Fermentation: Anaerobic process; produces less ATP than aerobic respiration.

• Types: Lactic acid fermentation, alcoholic fermentation.

• Facultative vs. Obligate Anaerobes: Facultative can use oxygen; obligate cannot.

Comparison Table: Aerobic vs. Anaerobic Respiration

Additional info: Some explanations and examples have been expanded for clarity and completeness.