Notes for Anatomy and Physiology - Chapter 3
Notes for Anatomy and Physiology - Chapter 3 BSC2085
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This 7 page Class Notes was uploaded by Hannah Hartman on Tuesday September 13, 2016. The Class Notes belongs to BSC2085 at Florida State University taught by Dr. Yung Su in Fall 2016. Since its upload, it has received 7 views. For similar materials see Anatomy & Physiology 1 in biological science at Florida State University.
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Date Created: 09/13/16
Chapter 3 - The Cell Organelles viernes, 9 de septiembre de 201612:51 PM An Introduction to Cells Learning Outcomes:3 -2 Describe the organelles of a typical cell, and indicate the specific functions of each. Organelles and the Cytoplasm • Cytoplasm ○ All materials inside the cell and outside the nucleus ○ Cytosol(intracellularfluid) § Dissolved materials □ Nutrients, ions, gases, proteins, and waste products ○ High potassium (K) and low sodium (Na ) found in cytosol (concentration difference is important for nerve cells to send electrical signals) ○ High protein (includes enzymes, structural proteins, etc.) ○ High carbohydrate/low amino acid and fat • Organelles ○ Structures with specific function. The Organelles can be divided into: 1. Nonmembranous organelles -No membrane ○ Direct contact with cytosol ○ Include the cytoskeleton, microvilli, centrioles, cilia, ribosomes, and proteasomes (do not confuse proteasomes with peroxisomes!) 2. Membranous organelles-Covered with plasma membrane ○ Isolated from cytosol ○ Include the endoplasmic reticulum(ER), the Golgi apparatus, lysosomes, peroxisomes, and mitochondria Nonmembranous Organelles 1. The Cytoskeleton ○ Structural proteins for shape and strength § Microfilaments —thin filamentscomposed of the protein a ctin □ Provides additional mechanical strength ® Anchors cytoskeleton to integral membrane proteins □ Interact with proteins for consistency of cytosol ® It forms a dense network = gelatinous cytosol ® If it is widelydispersed = fluid cytosol □ Pair with thick filaments of myosinfor muscle movement (interactions causes muscle contraction) □ Note: myosin proteins form thick filamentsin muscle tissue □ Interact with proteins for consistency of cytosol ® It forms a dense network = gelatinous cytosol If it is widelydispersed = fluid cytosol ® □ Pair with thick filaments of myosinfor muscle movement (interactions causes muscle contraction) □ Note: myosin proteins form thick filamentsin muscle tissue § Intermediate filaments —mid-sized between microfilaments and thick filaments. Keratin fibers in superficial layers of skin are intermediate filaments. □ Durable (most durable of the cytoskeletal elements) □ Strengthen cell and maintain shape □ Stabilize organelles □ Stabilize cell position with repect to surrounding cells § Microtubules —large, hollow tubes oft bulinprotein □ Attach to centrosomelocated close to the nucleus (microtubule organizing center) □ Strengthen cell and anchor organelles □ Change cell shape □ Move vesicles within cell ( kinesin and dynein –motor proteins that use ATP to move vesicles along microtubules; these proteins use the microtubules as "roadways" to move around the cell) □ Form spindle apparatus (moves chromosomes to opposite ends of the cell duria naphaseof cell division) 2. Microvilli –core composed of microfilaments • Increase plasma membrane surface area for absorption • Attach to cytoskeleton 3. Centriolesin the Centrosome(heart of the cytoskeleton) –composed of microtubules • Centrioles form spindle apparatus during cell division • Centrosome: cytoplasm surrounding centriole - microtubule radiate outward to cytoplasm from here. 4. Cilia – composed of microtubules ○ Cilia has a ring like structure, similar to centrioles. Do not confuse this with microvilli! This allow for movement of the extension (allowing for a fluttering motion) • Small hairlike extensions ○ Cilia move fluids across the cell surface of respiratory and reproductive systems 5. Ribosomes– used in translation(synthesis of polypeptides from instructions found on mRNA) ○ Uses mRNA as a template to create polypeptides ○ Two types § Free ribosomes in cytoplasm systems 5. Ribosomes– used in translation(synthesis of polypeptides from instructions found on mRNA) ○ Uses mRNA as a template to create polypeptides ○ Two types § Free ribosomes in cytoplasm □ Manufacture proteins for use insidethe cell § Fixed ribosomes attached to ER □ Manufacture proteins for secretion or for plasma membrane □ Note: fixed ribosomes start off as free ribosomes. The ribosome attaches to an mRNA strand, and as it produces the polypeptide, the specific sequence tells the ribosome to attach to the ER. 6. Proteasomes(don’t confuse with peroxisomes!) ○ Contain protein-digesting enzymes (proteases) ○ Disassemble damaged or viral proteins for recycling ○ Membranous organelles ○ Membranous Organelles – surrounded by a phospholipid membrane, isolates organelle from cytosol Six types of membranous organelles 1. Endoplasmic reticulum (ER) 2. Golgi apparatus - this is not technically linked to the ER, but they are linked in that they regulate and come in contact with similar products. 3. Lysosomes- these are connected to the ER and golgi because the proteins produced in the ER and sent to the golgi then interact with the lysosomes. These can be linked by a plasma membrane or have a "membrane flow" 4. Peroxisomes 5. Mitochondria 6. Nucleus-we will discuss in the next lesson All membranous organelles (except for the mitochondria and peroxisomes) are either interconnected or in communication through the movement of vesicles • Membrane flow – continuous exchange of membrane parts (via vesicles) Dynamic – allows adaptation and change ○ ○ Very active in secreting cells (area equal to entire membrane surface may be replaced each hour) ○ You can have a ER that is more active if Endoplasmic Reticulum (ER) • Endo-= within,p lasm = cytoplasm,r eticulum= network • Cisternae(hollow tubes, flattened sheets, and chambers) are storage chambers within membranes • General functions: a. Synthesis of proteins, carbohydrates, and lipids b. Storageof synthesized molecules and absorbed materials (ex. Ca2+ in muscle cells) within membranes • General functions: a. Synthesis of proteins, carbohydrates, and lipids b. Storageof synthesized molecules and absorbed materials (ex. Ca2+ in muscle cells) c. Transportof materials within the ER d. Detoxification( by enzymes inside the ER) of drugs or toxins absorbed into ER i. This is common in liver cells. • Two types of endoplasmic reticulum ○ Smooth endoplasmic reticulum (SER) § No ribosomes attached § Synthesizes lipids and carbohydrates □ Phospholipids and cholesterol (for maintenance and growth of membranes) - □ Steroid hormones (reproductive system) -androgens and estrogens □ Glycerides (storage in liver and fat cells) □ Glycogen (storage in muscles) ○ Rough endoplasmic reticulum (RER) § Surface covered with ribosomes § Active in protein and glycoprotein synthesis § Folds polypeptide protein structures § Encloses products i ransport vesicles □ Transport vesicles then deliver contents to the golgi apparatus § Note: amount of ER and proportion of RER to SER vary with cell type. □ Ex. Pancreatic cells that produce digestive enzymes have extensive RER and less SER. Cells in reproductive organs that produce steroids have extensive SER and less RER. 2. Golgi Apparatus ○ Vesicles enter forming (“cis”) face and exit maturing (“trans”) face § Vesicles enter from the ER to the cis face and after leaving the trans face move to lysosomes, the plasma membrane, etc. ○ Functions § Modifies and packages secretions □ Hormones or enzymes □ Substances are released by exocytosis § Renews or modifies the plasma membrane( vesicles released merge with the plasma membrane to alter it) § Packages special enzymes within vesicles for use in the cytoplasm (ex lysosomes) 3. Lysosomes- Powerful enzyme-containing vesicles (yso-= dissolve, oma= body □ Substances are released by exocytosis § Renews or modifies the plasma membrane( vesicles released merge with the plasma membrane to alter it) § Packages special enzymes within vesicles for use in the cytoplasm (ex lysosomes) 3. Lysosomes- Powerful enzyme-containing vesicles L(yso-= dissolve, oma= body ○ Used to break down & recycle large organic molecules and organelles ○ Primary lysosome - Formed by Golgi apparatus and inactive enzymes § Fusion of primary lysosome to endosome (transport vesicle) or damaged organelle forms: □ Secondary lysosome- Digestive enzymes activated to break down substances, isolate toxic chemicals □ Note - cytosol reabosrbes released nutrients frombreak down, remaining material expelled from cell ○ Lysosomes– function usually tightly controlled § Functions □ Clean up inside cells □ Breaks down large molecules □ Attack invading bacteria □ Recycle damaged organelles § Autolysis Auto-= selflysis= break □ Lysosomes membrane in damaged/dead cells break down, releasing stored enzymes (become active in cytoplasm) which destroys intracellular proteins/organelles § Lysosomal storage disease– more than 30 diseases affecting children □ Lack of specific lysosomal enzyme causes waste product build up. - ex. Tay-Sachs disease - rare disease caused by build up of lipids in brain cells. Infantile form leads to death of the individual (usually by age 4). 4. Peroxisomes –enzyme-containing vesicles (smaller than lysosomes and contains different enzymes) ○ Found in all cells, but highest in metabolically active cells such as liver cells ○ Functions include: Break down fatty acids, organic compounds § § Produce hydrogen peroxide (H2 2) during the reaction 5. Mitochondria – the “powerhouse” of the cell ○ Uses chemical energy in food (glucose) to produce the energy molecule ATP ○ Have smooth outer membrane and inner membrane with numerous folds(cristae) ○ Matrix: Fluid inside the cristae ○ Mitochondrial Energy Production § Glycolysis –converts glucose to pyruvic acid (in cytosol) for use in ATP ○ Have smooth outer membrane and inner membrane with numerous folds(cristae) ○ Matrix: Fluid inside the cristae ○ Mitochondrial Energy Production § Glycolysis –converts glucose to pyruvic acid (in cytosol) for use in the mitochondria § Citric acid cycle (also known as the Krebs cycle and the tricarboxylic acid cycle, or TCA cycle) □ Breaks down pyruvic acid to CO 2in matrix) □ Generates ATP and intermediates for the electron transport chain § Electron transport chai– found on the inner mitochondrial membrane □ Produces the most ATP compared to glycolysis and citric acid cycle □ Called aerobic metabolism (cellular respiration) ○ Mitochondria requires oxygen to break down food and produce ATP § If 2 not in enough quantity, citric acid cycle and electron transport chain shut down § Glucose + oxygen + ADP® carbon dioxide + water + ATP ○ Mitochondrial disorders –inherited, reduced ATP production. Cells throughout body may be affected. You should be able to: Explain the difference between membranous and no -n embranous organelles. List the membranous and non-membranous organelles Explain the difference in structure and function of the cytoskeletal elements Which is the largest? Which is the smallest? Explain the function of the centrioles, cilia and microvilli Explain the function of ribosomes and proteasomes Explain how all membranous organelles (except mitochondria) are in communication with each other Explain the function of the endoplasmic reticulum Explain the difference between smooth and rough endoplasmic reticulum Explain the function of the Golgi apparatus with each other Explain the function of the endoplasmic reticulum Explain the difference between smooth and rough endoplasmic reticulum Explain the function of the Golgi apparatus Explain the difference between lysosomes and peroxisomes Describe some diseases associated with lysosomes and mitochondria
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