Ch 4 Learning Objectives Updated PDF

1. Cell Theory and Surface Area to Volume Ratio: Cell Theory: States that all living organisms are made of cells, cells are the basic unit of life, and all cells come from pre-existing cells. Surface Area to Volume Ratio: As a cell grows larger, its volume increases faster than its sur...

1. Cell Theory and Surface Area to Volume Ratio: Cell Theory: States that all living organisms are made of cells, cells are the basic unit of life, and all cells come from pre-existing cells. Surface Area to Volume Ratio: As a cell grows larger, its volume increases faster than its surface area. A larger cell has more difficulty transporting nutrients and waste across the membrane because there’s less surface area compared to the volume. This is why cells remain small to efficiently exchange materials. (transporting nutrients and water across the membrane) 2. Differences Between Prokaryotic and Eukaryotic Cells: Prokaryotic Cells: Lack a nucleus and membrane-bound organelles. Have a single circular chromosome in the nucleoid. Example: Bacteria and Archaea. Cell Wall: Made of peptidoglycan in bacteria. Eukaryotic Cells: pseudomurein (archaea Have a nucleus and membrane-bound organelles (like mitochondria, ER). DNA is organized in linear chromosomes. Example: Animal, plant, fungal, and protist cells. Cell Wall: Present in plants (cellulose) and fungi (chitin), but not in animal cells. 3. Evolution of the 5 Kingdoms of Life: · Historically, life was classified into five kingdoms: Monera (prokaryotes), Protista (simple eukaryotes), Fungi, Plantae, -  Animalia. n 4. Structure and Function of Prokaryotic Features: Plasma Membrane: Regulates the passage of substances in and out of the cell. transportation of nutrients (NAG NAm) , Cell Wall: Provides structure and protection, made of peptidoglycan in bacteria. ↳ osmotic pressure Flagella: Used for movement; powered by a motor at the base. Axial Filament: Found in spirochetes, responsible for corkscrew movement. endoflagella-internal flagella Fimbriae and Pili: Hair-like structures that help with attachment conjugation (fimbriae) and genetic exchange (pili). cell to cell Pili-transfer DNA Capsule: Protects against the host immune system and aids in reatly adhesion. slime layer unorganized and loose = organized Glycocalyx: A sugar coating outside the cell wall that provides to bacterials protection and helps with adhesion. contributes & virulence. (ability to cause disease) Endospore: A tough, dormant form of the bacterium that can survive harsh conditions. Chromosome: A single, circular strand of DNA located in the nucleoid region. 5. Four Flagella Arrangements: O Monotrichous: A single flagellum at one end. sor Lophotrichous: A tuft of flagella at one or both ends. more than 2 20 Amphitrichous: One flagellum at each end. 10r2 S Peritrichous: Flagella all over the surface of the bacterium. 6. Four Components of the Plasma Membrane: # usid Mosaic (model of membrane held together by hydrogen bonds Phospholipids: Form the bilayer with hydrophobic tails inwardmembrane) and hydrophilic heads outward. Proteins: Integral and peripheral proteins that help with transport,(protins) signaling, and structural support. attachment Carbohydrates: Attached to proteins or lipids, these help with cell Glycocalyx LPs Lipopolysacharide)  recognition and communication. Cholesterol (in eukaryotic cells): Maintains membrane fluidity and stability. Stero (signaling structure) , 7. Four Types of Movement Across the Plasma Membrane: Simple Diffusion: Molecules move from high to low concentration without energy or proteins. no energy Rea small hydrophobic Facilitated Diffusion: Molecules move from high to low concentration with the help of transport proteins. Large hydophillic Protein Active Transport: Molecules move against their concentration L + oH transport gradient using energy (ATP). Pump Energy Red Osmosis: Water moves across the membrane from low to high solute concentration. Nate)seletive permeabla 8. Bacterial and Archaeal Cell Walls; Gram-Positive vs. Gram-Negative: Bacterial Cell Walls: Gram-Positive: Thick peptidoglycan layer, no outer membrane, stains purple. 40-60 layers techoic a cid Gram-Negative: Thin peptidoglycan layer, outer membrane with lipopolysaccharides (LPS), stains pink/red. 5-10 Layers Archaeal Cell Walls: Lack of peptidoglycan; have different polymers like pseudopeptidoglycan. 9. Gram Stain Procedure: Purpose: Distinguishes between Gram-positive and Gram-negative bacteria. Steps: 1. Crystal Violet: Stains all bacteria purple. 2. Iodine: Forms a complex with crystal violet, making it stick to the cell wall.  3. Alcohol/Acetone: Washes out the stain from Gram-negative bacteria. 4. Safranin: Counterstains Gram-negative bacteria pink/red. Cell Shapes and Arrangements of Bacteria: Shapes: Cocci: Spherical bacteria. fetr a 8 Bacilli: Rod-shaped bacteria. Spirilla: Spiral-shaped bacteria. Arrangements: Diplo-: Pairs. cocci Strepto-: Chains. Staphylo-: Clusters. - single bacilli > dipplo - rod 2x0X Streptobacilli > - 1. Bacterial Smear: What it is: A thin layer of bacteria spread on a slide. Why it’s important: It allows for staining and microscopic examination. How to prepare: Spread bacteria on a clean slide, let it air dry, and heat-fix it by passing it over a flame. 2. Acidic vs. Basic Dye & Simple Staining: Acidic dye: Has a negative charge and stains the background (e.g., nigrosin). Basic dye: Has a positive charge and binds to negatively charged bacterial cells (e.g., crystal violet). Purpose of simple staining: To enhance contrast and allow for observation of cell shape and arrangement. 3. Gram Stain, Acid-Fast Stain, Capsule, and Endospore Stain: Gram Stain: Differentiates bacteria based on cell wall structure (Gram-positive vs. Gram-negative). Acid-Fast Stain: Identifies mycobacteria with waxy cell walls. Capsule Stain: Visualizes the protective outer layer (capsule) around bacteria. Endospore Stain: Detects bacterial spores which are resistant to harsh conditions. 4. Importance of the Gram Stain & Staining Mycobacterium/Nocardia: Gram Stain: Crucial for bacterial classification and guiding treatment options. To identify Mycobacterium/Nocardia: Use the acid-fast stain because  their waxy, lipid-rich cell walls resist typical staining. 5. Negative Stain & Fixing: Negative stain: Does not color the cell because the dye is repelled by the negatively charged cell surface. Fixing: Necessary to kill the bacteria and adhere them to the slide, preventing them from being washed away during staining. 6. Appearance of Unstained vs. Stained Endospores: Unstained endospores: Appear as clear or refractile areas under the microscope. Stained endospores: Appear green when using the endospore stain (e.g., malachite green). 7. Evolution of Eukaryotic Cells & Endosymbiotic Theory: Eukaryotic cells likely evolved from prokaryotic cells via endosymbiosis, where a larger cell engulfed smaller cells (e.g., mitochondria and chloroplasts), which became organelles. 8. Structure and Function of Eukaryotic Organelles: Plasma Membrane: Controls entry/exit of substances. Cell Wall: Provides structure and protection (present in plants, fungi). Nucleus: Contains DNA; controls cellular activities. Rough ER: Synthesizes proteins. Smooth ER: Synthesizes lipids, detoxifies chemicals. Golgi Complex: Modifies, sorts, and packages proteins. Mitochondria: Produces ATP via cellular respiration. Lysosome: Breaks down waste and cellular debris. 9. Prokaryotes vs. Eukaryotes:  Prokaryotes: Simpler structure, no membrane-bound organelles, smaller (e.g., bacteria). Eukaryotes: Complex, with membrane-bound organelles, larger (e.g., plants, animals, fungi).