Chapter 4 Unit 2
Notes on Chapter 4: A Tour of the Cell
Page 2: Eukaryotic Cells and Prokaryotic Cells
Types of Cells
Prokaryotic cells: Found in Bacteria and Archaea.
Eukaryotic cells: Found in Protists, fungi, animals, and plants.
Page 3: Basic Features of All Cells
Common Features
Plasma membrane
Cytosol (semifluid substance)
Chromosomes (carry genes)
Ribosomes (synthesize proteins)
Page 4: Size Comparison
Cell Size
Prokaryotic cells: Typically 1–5 μm in diameter.
Eukaryotic cells: Typically 10–100 μm in diameter.
Page 5: Plasma Membrane
Functionality
Selective barrier for oxygen, nutrients, and waste.
Structure: Double layer of phospholipids.
Page 6: Surface Area to Volume Ratio
Metabolic Requirements
Limits on cell size due to surface area to volume ratio.
Smaller cells have a higher surface area to volume ratio.
Page 8-9: Eukaryotic Cell Structures
Key Organelles
Nucleus: Contains DNA, surrounded by nuclear envelope.
Endoplasmic Reticulum (ER): Rough (with ribosomes) and Smooth (without ribosomes).
Golgi Apparatus: Modifies and packages proteins.
Mitochondria: Site of cellular respiration.
Lysosomes: Digestive organelles.
Peroxisomes: Metabolic functions, produce hydrogen peroxide.
Cytoskeleton: Provides structure and support.
Page 10: Genetic Instructions
Nucleus and Ribosomes
Nucleus houses most DNA.
Ribosomes synthesize proteins using DNA information.
Page 11-12: The Nucleus
Structure and Function
Double membrane nuclear envelope.
Contains chromosomes and nucleolus (site of rRNA synthesis).
Page 13: Ribosomes
Protein Synthesis Locations
Free ribosomes in cytosol.
Bound ribosomes on ER or nuclear envelope.
Page 14: Endomembrane System
Components
Nuclear envelope, ER, Golgi apparatus, lysosomes, vacuoles, plasma membrane.
Functions in protein traffic and metabolic processes.
Page 15-17: Endoplasmic Reticulum (ER)
Types and Functions
Smooth ER: Lipid synthesis, detoxification, calcium ion storage.
Rough ER: Protein secretion, glycoprotein production, membrane factory.
Page 18: Golgi Apparatus
Functions
Modifies ER products, manufactures macromolecules, sorts and packages materials.
Page 19-20: Lysosomes
Digestive Functions
Hydrolytic enzymes digest macromolecules.
Involved in phagocytosis and autophagy.
Page 21-22: Vacuoles
Types and Functions
Food vacuoles from phagocytosis.
Contractile vacuoles in freshwater protists.
Central vacuoles in plants for storage and growth.
Page 24: Energy Conversion
Mitochondria and Chloroplasts
Mitochondria: Cellular respiration and ATP generation.
Chloroplasts: Photosynthesis in plants and algae.
Page 25-26: Endosymbiont Theory
Origins of Mitochondria and Chloroplasts
Similarities to bacteria support the theory of engulfed prokaryotes evolving into organelles.
Page 28: Mitochondria Structure
Components
Smooth outer membrane, inner membrane with cristae, compartments for metabolic processes.
Page 29: Chloroplasts
Photosynthesis
Contain chlorophyll and enzymes for capturing light energy.
Page 30: Peroxisomes
Functions
Produce and convert hydrogen peroxide, detoxify harmful compounds.
Page 31-33: Cytoskeleton
Structure and Function
Network of fibers for support and organization.
Composed of microtubules, microfilaments, and intermediate filaments.
Page 34-37: Microtubules
Functions and Structures
Support cell shape, guide organelle movement, separate chromosomes.
Centrosomes organize microtubules; cilia and flagella are extensions for movement.
Page 38: Plant Cell Walls
Structure and Function
Protects and maintains shape, prevents water uptake.
Composed of cellulose and polysaccharides.
Page 39: Extracellular Matrix (ECM) in Animal Cells
Composition and Function
Made of glycoproteins (collagen, proteoglycans).
Binds to integrins in the