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Ribosomes + RNA
Updated 28d ago
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endomembrane system Semi-autonomous organelles Protein sorting to organelles Systems biology of cells Cell Biology & Cell Theory Cell biology: The study of individual cells and their interactions. Cell Theory (Schleiden & Schwann, with contributions from Virchow): All living organisms are composed of one or more cells. Cells are the smallest units of life. New cells arise only from pre-existing cells through division (e.g., binary fission). Origins of Life: Four Overlapping Stages Stage 1: Formation of Organic Molecules Primitive Earth conditions favored spontaneous organic molecule formation. Hypotheses on the origin of organic molecules: Reducing Atmosphere Hypothesis: Earth's early atmosphere (rich in water vapor) facilitated molecule formation. Stanley Miller’s experiment simulated early conditions, producing amino acids and sugars. Extraterrestrial Hypothesis: Organic carbon (amino acids, nucleic acid bases) may have come from meteorites. Debate exists over survival after intense heating. Deep-Sea Vent Hypothesis: Molecules formed in the temperature gradient between hot vent water & cold ocean water. Supported by experimental evidence. Alkaline hydrothermal vents may have created pH gradients that allowed organic molecule formation. Stage 2: Formation of Polymers Early belief: Prebiotic synthesis of polymers was unlikely in aqueous solutions (water competes with polymerization). Experimental evidence: Clay surfaces facilitated the formation of nucleic acid polymers and polysaccharides. Stage 3: Formation of Boundaries Protobionts: Aggregates of prebiotically produced molecules enclosed by membranes. Characteristics of a protobiont: Boundary separating the internal & external environments. Polymers with information (e.g., genetic material, metabolic instructions). Catalytic functions (enzymatic activities). Self-replication. Liposomes: Vesicles surrounded by lipid bilayers. Can enclose RNA and divide. Stage 4: RNA World Hypothesis RNA was likely the first macromolecule in protobionts due to its ability to: Store information. Self-replicate. Catalyze reactions (ribozymes). Chemical Selection & Evolution: RNA mutations allowed faster replication & self-sufficient nucleotide synthesis. Eventually, RNA world was replaced by the DNA-RNA-protein world due to: DNA providing more stable information storage. Proteins offering greater catalytic efficiency and specialized functions. Microscopy Microscopy Parameters Resolution: Ability to distinguish two adjacent objects. Contrast: Difference between structures (enhanced by special dyes). Magnification: Ratio of image size to actual size. Types of Microscopes Light Microscope: Uses light; resolution = 0.2 micrometers. Electron Microscope: Uses electron beams; resolution = 2 nanometers (100x better than light microscopes). Light Microscopy Subtypes Bright Field: Standard; light passes directly through. Phase Contrast: Amplifies differences in light phase shifts. Differential Interference Contrast (DIC): Enhances contrast for internal structures. Electron Microscopy Subtypes Transmission Electron Microscopy (TEM): Thin slices stained with heavy metals. Some electrons scatter while others pass through to create an image. Scanning Electron Microscopy (SEM): Heavy metal-coated sample. Electron beam scans the surface, producing 3D images. Cell Structure & Function Determined by matter, energy, organization, and information. Genome: The complete set of genetic material. Prokaryotic vs. Eukaryotic Cells Feature Prokaryotic Cells Eukaryotic Cells Nucleus ❌ Absent ✅ Present Membrane-bound organelles ❌ None ✅ Yes Size Small (1-10 µm) Large (10-100 µm) Examples Bacteria, Archaea Plants, Animals, Fungi, Protists Prokaryotic Cell Structure Plasma Membrane: Lipid bilayer barrier. Cytoplasm: Internal fluid. Nucleoid Region: DNA storage (no nucleus). Ribosomes: Protein synthesis. Cell Wall: (Some) Provides structure & protection. Glycocalyx: Protection & hydration. Flagella: Movement. Pili: Attachment. Eukaryotic Cell Structure Nucleus: Contains DNA & controls cell functions. Organelles: Rough ER: Protein synthesis & sorting. Smooth ER: Lipid synthesis, detoxification. Golgi Apparatus: Protein modification & sorting. Mitochondria: ATP production (Powerhouse of the Cell™). Lysosomes: Digestive enzymes for breakdown & recycling. Peroxisomes: Breakdown of harmful substances. Cytoskeleton: Provides structure (microtubules, actin filaments, intermediate filaments). Plasma Membrane: Regulates transport & signaling. Endomembrane System Includes: Nucleus, ER, Golgi apparatus, lysosomes, vacuoles, and plasma membrane. Nuclear Envelope: Double membrane structure. Nuclear pores allow molecule transport. Golgi Apparatus: Modifies & sorts proteins/lipids. Packages proteins into vesicles for secretion (exocytosis). Lysosomes: Contain acid hydrolases for macromolecule breakdown. Perform autophagy (organelle recycling). Semi-Autonomous Organelles Mitochondria Function: ATP production (cellular respiration). Structure: Outer & inner membrane (inner folds = cristae for increased surface area). Mitochondrial matrix houses metabolic enzymes. Chloroplasts (Plants & Algae) Function: Photosynthesis (light energy → chemical energy). Structure: Outer & inner membrane. Thylakoid membrane (site of photosynthesis). Contains chlorophyll. Endosymbiosis Theory Mitochondria & chloroplasts evolved from free-living bacteria that were engulfed by an ancestral eukaryotic cell. Protein Sorting & Cell Organization Co-translational sorting: Proteins destined for ER, Golgi, lysosomes, vacuoles, or secretion. Post-translational sorting: Proteins sent to nucleus, mitochondria, chloroplasts, peroxisomes. Systems Biology Studies how cellular components interact to form a functional system
Updated 34d ago
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Key Concepts: Cell Theory, Cell Structure & Function, Prokaryotic vs. Eukaryotic, Cell Membrane, Microscopes, Passive vs. Active Transport, Diffusion, Osmosis, Energy (Potential vs. Kinetic), Photosynthesis & Cell Respiration (Aerobic vs. Anaerobic), Fermentation (Lactic Acid & Alcoholic) 1. Describe one similarity and one difference between the two terms in each of the following pairs: a. Eukaryote, prokaryote Eukaryote: Has a membrane-bound nucleus in the cell Prokaryote: No nucleus, DNA free-floating in the cell, can have flagellum Both: have cell membranes, have DNA, have ribosomes b. Cell wall, cell membrane Cell wall: rigid, not as flexible, more selective (harder for things to pass through) Cell membrane: fluid, flexible, selectively permeable Both: enclose cell, facilitate what goes in/out of cell c. Diffusion, facilitated diffusion Diffusion: movement of particles from high to low concentration Facilitated diffusion: movement of particles through channel proteins Both: are passive transport (no energy required), particles move from HIGH to LOW 2. Describe the structure of a phospholipid bilayer. There are 2 layers of phospholipids (consisting of hydrophilic heads and hydrophobic tails) 3. Explain the following diagram using the terms: diffusion, cell membrane, low concentration, energy, high concentration. The water molecules are moving across the cell membrane to reach a state of equilibrium. The molecules move from HIGH to LOW concentration, so they move downwards across the membrane. This is an example of diffusion, or passive transport - this does not require energy because it is fueled by the difference in concentrations. 4a. What is the microscope magnification of the eye piece? scanning? low power? high power? ● Eye piece = 10x ● Scanning = 4x ● Low power = 10x ● High power = 40x b. If you were looking at an onion cell using the high power lens, what is the TOTAL MAGNIFICATION at which you are looking at the cell? High power = 40x Eye piece = 10x 40 x 10 = 400x Your total magnification would be 400x using the higher power objective lens. 5. Identify the difference between hypertonic, isotonic, and hypotonic solutions: A = isotonic B = hypotonic C = hypertonic 6. How is active transport different from diffusion and facilitated diffusion? ● Active Transport = requires energy, molecules are forced AGAINST the gradient from LOW to HIGH concentration ● Diffusion = does not require energy, molecules move from HIGH to low concentration ● Facilitated diffusion = does not require energy, molecules move from HIGH to low concentration, but it requires the help of channel proteins (typically larger molecules) 7. Explain what is happening in the following picture. This is an example of ENDOCYTOSIS (Active Transport) - there is a chemical/nutrients being taken into the cell when it’s engulfed by the cell membrane (becomes a vesicle). 8. What is the difference between potential and kinetic energy? Give an example of each. a. Poyential energy - stored energy; e.g,glucose, a ball at the topof ahill b. Kinetic energy - energy of motion e.g., a car onthe freeway 9. Write out the full chemical reaction for PHOTOSYNTHESIS. What organelle is responsible for this? Chloroplast 10. Write out the full chemical reaction for CELL RESPIRATION. What organelle is responsible for this? Mitochondria 11. If we are at 400X magnification (field diameter is 450 micrometers), and there are 10 cells that fit across the diameter of what we’re seeing, what is the estimated size of ONE cell? 450 nanometers / 10 cells = 45 nanometers per cell 12. What is the role of the stomata? What is the role of the guard cells? Stomata role isgas exchange to let oxygen and carbondioxide pass through, as needed for key processes such as photosynthesis and cellular respiration. Guard cells arepairs of cells that surround the stomata and controlgas exchange by regulatingthe openingand closure of stomata. 13. What would cause guard cells to swell and open stomata? What would cause guard cells to shrink and close stomata? → Whentheplanthas anexcess of water, theguard cells swell and create anopeningfor the exchange ofgas → Whentheplanthas a lack of water, theguard cells shrink and close the openingfor the exchange ofgas 14. In fermentation, what relationship exists between the amount of available sugar and amount of carbon dioxide produced? → As more sugar is available, there will be more fermentationthathappens, and more carbondioxideproduced → There is a direct relationshipbetweenthose two factors 15. List the # of ATP produced by each of the following: Glycolysis = 2 ATP Krebs = 2 ATP ElectronTransport = 34 ATP 16. Explain one example of lactic acid fermentation. Explain one example of alcoholic fermentation. a. Lactic acid fermentation- heating milk and combiningit withtwo live bacteria cultures, resultinginthe bacteria breakingdownthe sugars in milk and releasinglactic acid (distinct tart/sour taste) b. Alcoholic fermentation- yeast and bacteria beingadded to tea and fruit (sugar), resultinginkombucha withethanol and carbondioxide bubbles
Updated 105d ago
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ribosomes
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Ribosomes
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Ribosomes
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Ribosomes
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