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. Each class has unique monomers and functions.

• Polymer: A long molecule consisting of many similar or identical building blocks (monomers) linked by covalent bonds.

• Monomers: The repeating units that serve as building blocks of a polymer. Examples include monosaccharides (carbohydrates), amino acids (proteins), nucleotides (nucleic acids).

• Dehydration Synthesis: A chemical reaction that builds polymers by removing water.

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

Example: Starch is a polymer of glucose; proteins are polymers of amino acids.

Carbohydrates

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

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

• Types: Monosaccharides (glucose), disaccharides (sucrose), polysaccharides (starch, cellulose).

Lipids

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

• Triglyceride Structure: Composed of glycerol and three fatty acids.

• Phospholipids: Major component of cell membranes, with hydrophilic heads and hydrophobic tails.

• Functions: Energy storage, membrane structure, signaling.

Proteins

Proteins are polymers of amino acids, performing diverse functions in cells.

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

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

• Shape Determination: The sequence of amino acids and chemical properties determine protein folding and function.

Nucleic Acids

Nucleic acids (DNA and RNA) store and transmit genetic information.

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

• Comparison: Both carry genetic information, but differ in structure and function.

Chapter 6: Tour of the Cell

Cell Theory and Types

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

• Plasma Membrane: Encloses the cell, controlling entry and exit 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 unique structures.

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

• Animal Cell Organelles: Lysosomes, centrioles.

Cell Structures and Functions

Cells contain various organelles, each with specific functions.

• Nucleus: Stores genetic material.

• Endomembrane System: Includes the endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, and peroxisomes.

• Mitochondria and Chloroplasts: Sites of energy conversion; mitochondria for cellular respiration, chloroplasts for photosynthesis.

• Cytoskeleton: Microfilaments, intermediate filaments, microtubules provide structural support and movement.

Cell Surface and Junctions

Cells interact with their environment and other cells through specialized structures.

• Cilia and Flagella: Structures for movement.

• Extracellular Matrix: Provides structural support outside animal cells.

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

Chapter 7: Membrane Structure and Function

Cell Membranes

Cell membranes are selectively permeable barriers composed mainly of phospholipids and proteins.

• Functions: Protects the cell, controls transport, facilitates communication.

• Phospholipid Structure: Hydrophilic head and hydrophobic tail create a bilayer.

Transport Across Membranes

Cells transport substances across membranes via passive and active mechanisms.

• Passive Transport: Diffusion and osmosis; no energy required.

• Osmosis: Diffusion of water across a membrane.

• Hypertonic, Hypotonic, Isotonic Solutions: Affect water movement and cell volume.

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

• Active Transport: Requires energy to move substances against their concentration gradient.

• 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.

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

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

• ATP: The main energy currency of the cell; couples exergonic and endergonic reactions.

Equation:

Enzymes

Enzymes are biological catalysts that speed up chemical reactions by lowering activation energy.

• Activation Energy: The energy required to start a reaction.

• Factors Affecting Enzyme Activity: Temperature, pH, substrate concentration.

Chapter 9: Cellular Respiration and Fermentation

Overview of Cellular Respiration

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

• 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 that transfer energy to the electron transport chain.

Fermentation

Fermentation allows cells to produce ATP without oxygen.

• Types: Lactic acid fermentation (in muscle cells), alcoholic fermentation (in yeast).

• Facultative Anaerobes: Organisms that can survive with or without oxygen.

Comparison Table: Cellular Respiration vs. Fermentation

Additional info: Some explanations and examples were expanded for clarity and completeness based on standard General Biology curriculum.