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UM BIOM 250N - Cell Wall and Cytoplasmic Structures

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BIOM 250 1st Edition Lecture 4Outline of Last Lecture I. Cell Structure and Function of ProkaryotesII. Prokaryotes III. Gram Positive CellsOutline of Current LectureI. Gram Negative Cell WallII. Movement Across MembranesIII. Bacterial Cytoplasm StructuresIV. Eukaryotic CellCurrent LectureI. Gram Negative Cell Walla. Outer membranei. Lipopolysaccharide (LPS), lipoproteins, and phospholipidsii. Strong negative charge, protective against enzymes, antibiotics, detergents, bile saltsiii. Contains pores (porins) to allow transport of need nutrientsiv. LPS has three components:1. Lipid A (endotoxin) that is embedded into the outer membrane—most toxins come from lipid A2. Core polysaccharide- attached to lipid A and is usually a constant structure3. O polysaccharide- attached to core and is a variable structurev. Peptidoglycan- contrary to gram positive cells, gram negatives have a thin peptidoglycan layervi. Perplasmic space- between outer membrane and inner plasma membrane1. Contains degradative enzymes and transport proteins2. Outer membrane and peptidoglycan linked by lipoproteinsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.b. Cytoplasmic membranei. Structure1. Lipid bilayer (phospholipids); amphipathic2. Proteins are either integral (transmembrane) or peripheral3. Also glycoproteins and glycolipids4. Fluid mosaic model—proteins can move in bilayerii. Functions1. barrier with selective permeability2. Small uncharged molecules such as water and carbon dioxide passeasily through3. Oxygen and non-polar molecules enter lipid layer4. Large molecules (proteins and some sugars) cannot pass through5. Most substances require transport molecules6. Enzymes in the membrane break down nutrients which aids in energy productionc. Movement across membranesi. Passive Transport1. Simple diffusion- movement of a solute from an area of high concentration to an area of low concentration 2. Facilitated diffusion- solute combines with a transporter protein inthe membraneii. Active Transport- requires a transporter protein and ATP1. Group translocation- requires a transporter protein and PEP2. Molecules move AGAINST their gradientiii. Osmosis- movement of water across a selectively permeable membrane from an area of high water concentration to an area of lower water concentration1. Osmotic pressure- the pressure needed to stop the movement of water across the membraneII. Bacterial Cytoplasm Structures:a. Nucleoidi. Usually single molecule of DNA ii. Attached to plasma membrane, no envelope, no histonesiii. Can have plasmids- extrachromosomal DNA1. Can contain gees (5-100) for antibiotic resistance, enzymesb. Ribosomesi. Formed of protein and RNA (rRNA)ii. Site of protein synthesisc. Inclusionsi. Areas of nutrient deposition (phosphate, sugars, lipids, gas vesicles)ii. Carboxysomes- contain photosynthetic enzyme ribulose d. Endosporei. Certain bacteria form a dormant “seed” under nutrient poor conditionsii. Spores survive heat, cold, dryness and radiationiii. Found in Clostridium (tetanus, botulism) and Bacillus (athrax)iv. Killed by autoclavingv. Sporulation- vegetative (growing) cell forms septum around replicated DNA and cytoplasm1. Double-layered spore is coated with peptidoglycan and protein layers2. Contains DNA, RNA, ribosomes, enzymes, and some nutrients3. Germination triggered by physical or chemical changes4. Septum- an outer layerIII. Eukaryotic Cella. Contains a true nucleus and membrane bound organellesb. Contains few, long flagella and many, short ciliai. These function in motilityc. Cell wall- only for some groupsi. Plants/algae have a cellulose cell wall, fungi have chitin, protozoa have a protein pellicled. Glycocalyx- sticky sugarsi. Glycoproteins, glycolipidsii. Act in attachment and cell to cell


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