BSC 215- Week 4 Notes
BSC 215- Week 4 Notes BSC 215
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This 9 page Class Notes was uploaded by Alexia Acebo on Friday February 5, 2016. The Class Notes belongs to BSC 215 at University of Alabama - Tuscaloosa taught by Dr. Jason Pienaar in Summer 2015. Since its upload, it has received 24 views. For similar materials see Human Anatomy & Physiology I in Biological Sciences at University of Alabama - Tuscaloosa.
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Date Created: 02/05/16
BSC 215- Week 4 Notes Lecture 5 -The Cell Membrane- **All life is cell based LO 1. Understand “cell theory” and scientific discoveries that led -We didn’t know about cells until the microscope Biology: technology drives the science Robert Hook Anton Van Leeuwenhoek st Louis Pasteur (1 experiments) Schleiden & Swan o 3 Tenets of cell theory: 1. All living organisms are composed of cells 2. The cell is the most basic unit of life 3. All cells come from pre-existing cells LO 2. Understand Variation and Limits on cellular morphology Morphology: Shape and Size Shape Variation: Skin cells Egg cells Nerve cells Bacterial cells Plant cells Size Variation: Sperm (small) v. egg (big) SIZE: Egg cell- 100 micrometer diameter Nerve- >1m long Most human cells- 10-15 micrometer diameter **When s/v ratio too small: cell not functional LO 3. Know the 3 Basic components of cells and the terminology used to describe them - Plasma membrane: what composes the cell - Extracellular space/fluid: anything outside of the cell - Intracellular space/ fluid: inside cell (mostly water) - Cytoplasm: Liquid- cytosol, solid- organelles, cytoskeleton (protein network) - Nucleus: double stranded DNA inside, all life has some area where hereditary material is found - Nuclear envelope: 2x plasma membrane surrounding nucleus LO 4. Describe how lipids, carbs and proteins are distributed in a cell membrane and explain their respective functions AMPHIPATIC 2 Lipids in Cell membrane -phospholipids -cholesterol (stiffer) LIPIDS charged head, non charged head, fatty acid tail 98% of membrane molecules are lipids o 75% phospholipids amphipatic form bilayers o 20% cholesterol stiffen membrane o 5% glycolipids glyco+lipid form part of glycocalyx (sugar coating of cell) PROTEINS 2% of membrane molecules (50% mass) 2 major classes o Integral o Peripheral -Membrane Proteins- Carbohydrates Glycocalyx o Glycolipids o Glycoproteins Unique identifier o Guides embryonic cells to detinations o Immune functions o Adhesion functions LO 5. Understand passive transport mechanisms across cell membranes Passive Transport DOES NOT require energy DIFFUSION OSMOSIS Movement of solutes Movement of solvent down a concentration down a concentration gradient gradient (semi-perm membrane) **Cell membranes are selectively permeable Based on: o Size o Charge Hydrophobic v. phyllic o Membrane protein specificity BUT still just diffusion Simple v. Facilitated Diffusion distinguished by need for energy SIMPLE FACILITATED Directly through the Carrier Mediated: membrane (Hydrophobic, protein specific for 1 small molecules) chemical, binding of substrate causes shape change in transport protein Channel mediated: mostly ions selected on basis of size and charge Factors Affecting Membrane Diffusion rate Temperature o Increase in temp., particles move faster, quicker diffusion Molecular mass o Larger molecules diffuse slower and vice versa Concentration Gradient o Greater, more diffusion Membrane surface area o Increase= more space for solutes to move across Membrane permeability o More permeable= faster o Hydrophobic will diffuse faster than hydrophyllic Osmosis Diffusion of solvent across a membrane Water flows DOWN a concentration gradient Dissolved solutes determine water concentrations Hydration spheres also help TONICITY **most cells= 1% solution (isotonic) Aquaporins Some water always diffuses across the plasma membrane o Water is small and partially charged o Aquaporins embedded in cell membrane to let water flow **can control osmotic rate by varying aquaporin # -Diffusion Summary- SIMPLE CARRIER CHANNEL MEDIATED MEDIATED Hydrophobic No energy Osmosis/aquapor ins LO 6. Understand active transport mechanisms across cell membrane -Diffusion, whether simple or facilitated ALWAYS passive Membrane Protein Pumps -The Sodium Potassium Pump- **ALL animals have them crucial for: nerve cell signaling, skeletal muscle contraction, heart beat, osmotic balance antiporter- Na one way, K other way ATPase- breaks down ATP to pump !MAINTAINS SODIUM OUTSIDE! !MAINTAINS POTASSIUM INSIDE! -up to 30% of our energy is used for this pump Na/K pump primary active transport -uses ATP as energy source -Secondary Active Transport- Glucose Symporter Vesicular Transport Movement of large particles or many molecules simultaneously through membranes in membrane derived processes o Endocytosis: into cell Phagocytosis: cell eating Pinocytosis: cell drinking Receptor mediated endocytosis: specific molecule transport o Exocytosis: out of cell Clicker Quiz (2/4/16) 3 main components of the cell o plasma membrane, cytoplasm, nucleus Difference between active/ passive transport o Energy Na/K pump o 2K in, 3 Na out not part of endomembrane system o cilia secondary active transport o glucose symporter Lecture 6 -Cytoskeleton and Organelles- Cell ultrastructure - plasma membrane - nucleus - nuclear envelope - ribosomes - mitochondrion - golgi complex LO 1. Describe the structure/function of each organelle Mitochondria powerplant of the cell specialized for ATP synthesis double membrane o inner membrane: cristae (folds) surrounds matrix Ribosomes specialized for protein synthesis large and small protein subunits o present in every living organism free in cytosol or bound to rough ER & nuclear membranes Endoplasmic Reticulum network of cisternae (tubules) continuous with outer nuclear membrane o Rough ER studded with ribosomes Protein folding Membrane factory Combines integral proteins and lipids prefabricated cell membrane sections o Smooth ER No ribosomes Calcium ion storage Detoxification reactions Lipid synthesis
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