Cell seminar


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Cell seminar

  1. 1. Contents Introduction to cell History Number and cell size Cell type Structure of cell Cell membrane Cytoplasm Organelle in cytoplasm Nucleus Cell surface contact Molecule movement Endocytosis and Exocytosis References
  2. 2. Cell Cell-Structural and functional unit ofthe living body. Smallest living unit Most of cells aremicroscopic
  3. 3. Discovery of Cells Robert Hooke (Mid 1600) Coined term cell First seen cork plant cell (1889) Rudolf Virchow“all cells come from cells”
  4. 4. Number Unicellular(consist of a single cell)-Bacteria, Virus Multicellular – Human (Around 100 trillioncells)-Other animalAmoeba proteus
  5. 5. Cell size Most of cell are between 5-50μm indiameter Ex,RBC-7.5 μmColumnar epithelial cells 20 μm talland 10 μm wide Larger cellsSkeletal muscle cellNeurons
  6. 6. Can we see the cell
  7. 7. Cell Size
  8. 8. Cell Types Prokaryotic Eukaryotic
  9. 9. Prokaryotic cell First cell type on earth Cell type of Bacteria and Archaea No membrane bound nucleus Nucleoid = region of DNA concentration
  10. 10. Eukaryotic cell Organelles not bound by membranes Nucleus bound by membrane Fungi, Protists, Plant, and Animal cells Possess many organellesAnimal cellPlant cell
  11. 11. Structure of cell Each cell is formed by cell body andmembrane Cell membrane –Separate cell body fromthe surrounding cell Cell body -CytoplasmNucleus
  12. 12. Cell membrane Protective sheath enveloping the cell body Separate intracellular and extracellular fluid Permits exchange of some substance Thickness- 75A to111A Double layer ofPhospholipids & Proteins
  13. 13. lipid layer Cell membrane-Bilayered component Lipids are cholesterols and phospholipids Phospholipids = Phosphrous and fatty acid(Amino Phospholipid, Phosphetidyle GlycerolPhosphetidyle Inositol)Outer part- Hydrophilic(soluble in water)Inner part- Hydrophobic(soluble in fat)
  14. 14. Significance of lipid layer Forms semi-permeable membrane Fat soluble substance can pass through it.-O2, CO2 and alcohols Barrier to water soluble materials-Glucose, Urea, Electrolytes
  15. 15. Protein layer Glycoprotein Two type Integral protein and peripheral protein
  16. 16. Significance of protein layer Integral proteins- Structural IntegrityChannels(formed by integral protein)Diffusion of water soluble substanceGlucose, Electrolytes Receptors proteinReceptor for hormones andneurotransmitterRecognize certain chemicals Carrier protein-Transport of substance(active or passive) Act as antigen-act as antigen and provide antibodyformation
  17. 17. Significance of MembraneProtein
  18. 18. Carbohydrate Attached to protein or lipid Significance- Negatively charged-Glucocalyx of neighboring cellhelp in tight fixation.-Receptor for some hormone-Contain specific antigen(RBC-blood groupantigen)
  19. 19. Cytoplasm Viscous fluid containing organelles Interconnected filaments & fibers Organelles Fluid= Cytosol Various particles(Different shape and size)-Proteins, Carbohydrate,lipids and Electrolytes. 200mg/ml of protein High K + low Ca+2 low Na+
  20. 20. Cytoskeleton Filaments & Fibers Made of 3 fiber types◦ Microfilaments◦ Microtubules◦ Intermediate filaments 3 functions:◦ Mechanical support◦ Anchor organelles◦ Help move substancesTransportShape of cellActin and myosinShape of cell
  21. 21. A = actin, IF = intermediate filament, MT = microtubule
  22. 22. Organelle in Cytoplasm Organelle caries out various functions Two type- Bound by limiting membraneEndoplasmic reticulumGolgi apparatuslysome, PeroxisomeMitochondria Not bounded by limiting membraneChromosome, RibosomeMicrofilaments, Microtubules
  23. 23. Endoplasmic Reticulum Network of tubular and micrsomalvesicular structure Outer side-Limiting Membrane Inner side- Endoplasmic Matrix(lumen) Helps to move substances within cellsTwo types◦ Rough endoplasmic reticulum◦ Smooth endoplasmic reticulum
  24. 24. Rough endoplasmic reticulum Ribosomes are attached to surface◦ Manufacture proteins◦ Not all ribosomes attached to rough ER May modify proteins from ribosome Protein pass through membrane andaccumulate in cisternae.
  25. 25. Smooth EndoplasmicReticulum No attached ribosomes Various enzymes are present on outersurface Enzymes- Metabolic process of cell
  26. 26. Smooth endoplasmic reticulum with associated vesiclesBy courtesy of Rose Watson, Cancer Research UK.
  27. 27. Significance of Smooth EndoplasmicReticulum Carbohydrate metabolism Synthesis of non protein substance◦ Cholesterol◦ Steroid hormones◦ Sebum Catabolism of toxic substance Cooperate with rough endoplasmic reticulumand Golgi apparatus to synthesize new cellmembrane. Specialized typeIn skeletal muscle-sarcoplasmic reticulum
  28. 28. Golgi Apparatus or GolgiBody Present in all cell except Red Blood Cell Situated near nucleus Consist of 5 to 8 membranous sac The Sacs are flattened and called asCisternae
  29. 29. Function of Golgi Body Processing and delivering the proteinmolecule to different parts of the cell.Protein synthesized from endoplasmic reticulumTransported in the form of Reticular VesicleTo Golgi Body where it is processed and sorted outPacked in the form of Secretory Granules, SecretoryVesiclesVesicles delivered by golgi body leave the cellby exocytosis.lysosomal Vesicles
  30. 30. Lysosomes Vesicular organelle 80 to 800nm in diameter Have thickest covering membrane Many small granules present in lysosomes Contain digestive enzymes(hydrolyticenzyme) More than 40 different type of hydroxylases All enzyme- lysozymes
  31. 31. Functions◦ Digests protein, carbohydrate, Lipid,nucleic acids◦ Destruction of bacteria and other foreignbody.◦ Removal of unwanted cell in embryo◦ Break down old cell parts◦ When bacteria enter into the celllysosomes rupture and immediately digestthe invaded bacteria or foreign body.
  32. 32. Lysosomal storage disease Enzymes are defective because of gene Materials that they normally degrade willaccumulate within late endosomes and lysosomes.e.g. Tay-Sachs disease Hurlers Syndrome: Failure to metabolize certainmucopolysaccharides causes the accumulation oflarge amounts of matrix within connectivetissue, which distorts the growth of many parts ofthe body.
  33. 33. Peroxisome Membrane limited vesicle Derived from endoplasmic reticulum Contain oxidative enzymes (Urate oxidase and D- aminoacidoxidase)
  34. 34. Function of peroxisome Hydrogen peroxide is produced bypoisons or alcohol(ethanol and formaldehyde) Peroxisome ruptures when hydrogenperoxide is formed in cell. Oxidases destroys hydrogen peroxide Also destroy other enzymes necessaryfor its production Gluconeogenesis from fats anddegradation of purine and fat.
  35. 35.  Zellweger syndromeGenetic abnormality in peroxisomebiogenesis
  36. 36. Mitochondria Rod shaped, oval shaped structure Diameter - 0.5 to 1 μm Bilayered membranous organelleOuter layer- SmoothInner layer- Series of shelf like projection-Cristae(provide large surface area) Contain RNA and DNA
  37. 37.  Principle source of chemical energy inmost of the cells Enzymes are located in mitochondrialmatrix and inner mitochondrial matrix.
  38. 38. Function Break down fuel molecules (cellularrespiration)GlucoseFatty acids Production of energy by catabolism ofdigested food particles Stored in the form of ATP molecules So It is power house of cell Energy released by breakdown of ATPmoleculeWhen needed Mitochondria contain enzymes for citric acid
  39. 39.  Mitochondria are distributed within a cellaccording to regional energyrequirements-Near the base of cilia-Near basal domain of cells of proximalconvulated tubules-Proximal end of flagellum Genetic diseases of mitochondria affectperticular tissuesEx. Mitochondrial myopathiesMitochondrial neuropathies
  40. 40. Ribosomes It is granular structure Diameter of 15 to 20 nm Contain 65%RNA and 35% Protein Some ribosomes remain free incytoplasmFunction of free ribosome Synthesis of protein from amino acid Synthesis of protein part ofhemoglobin Protein molecules of peroxisome
  41. 41. Nucleus Control center of cell 3 to 10 μm in diameter Double membrane(Nuclear membrane) Contains◦ Nucleoplasm◦ Nucleolus
  42. 42. Nuclear membrane Double layered, porous in nature Communicate with cytoplasm Outer layer continuous as endoplasmicreticulum Inner space forms lumen of endoplasmicreticulum Pores- Guarded by protein- Diameter 80nm to 100nm
  43. 43. Nuclear envelope with nuclear pores
  44. 44. Nucleoplasm Gel like substance Contain DNA Called aschromatin One or more in each nucleus Contain RNA and some proteins RNA synthesized by 5 pairs ofchromosome Condensed to form subunit of ribosome Subunit travel to cytoplasm through pore Fusion of subunits lead to formation ofRibosomeNucleoli
  45. 45. Function of Nucleus Control center for all activity of cell It sends genetic information in the formof DNA to cytoplasm for synthesis ofspecific enzymes Enzymes are responsible for variousmetabolic reactions. Genes present in the nucleus controlscell division. The hereditary information is stored inthe nucleus and transferred fromone generation to next.
  46. 46. Cell surface contactTwo type-General adhesive contactcalcium dependentcalcium independent-Specialized contact
  47. 47. General adhesive contactCalcium dependent adhesion moleculeCadherinsselectinsIntegrinsCalcium independent adhesionmoleculeMost are transmembrane proteinsN-CAMsI-CAMs
  48. 48. Specialized Adhesive ContactsOccluding Junction( Tight junction )-Tight junction is made up of ridges-Ridges have two halves which are inclose contact- provide strength and stability-prevent movement of ions and proteinDesmosomesHemidesmosomes
  49. 49. Communicating junction(gap junction) Cytoplasm of two cells is connected bychannels Diameter of channel 3 nm Passage of Ions, Glucose, Amino acid Rapid propagation of action potentialConnexon
  50. 50. Molecule Movement & Cells Passive Transport Active Transport Endocytosis(phagocytosis & pinocytosis) Exocytosis
  51. 51. Passive Transport No energy required Move due to gradient◦ differences inconcentration, pressure, charge Move to equalize gradient◦ High concentration moves toward lowconcentration.
  52. 52. Types of Passive Transport1. Diffusion2. Osmosis3. Facilitated diffusion
  53. 53. Diffusion Molecules move toequalize concentrationOsmosis Special form of diffusion Fluid flows from lower soluteconcentration Often involves movement of water◦ Into cell◦ Out of cell
  54. 54. Solution Differences & CellsSolvent + Solute = Solution Hypotonic◦ Solutes in cell more than outside◦ Outside solvent will flow into cell Isotonic◦ Solutes equal inside & out of cell Hypertonic◦ Solutes greater outside cell◦ Fluid will flow out of cell
  55. 55. Facilitated Diffusion Differentially permeable membrane Channels (are specific) help moleculeor ions enter or leave the cell Channels usually are transportproteins(aquaporins facilitate the movement ofwater) No energy is used
  56. 56. Process of Facilitated Transport Protein binds with molecule Shape of protein changes Molecule moves across membrane
  57. 57. Active Transport Molecular movement Requires energy (against gradient) Example is sodium-potassium pump
  58. 58. Endocytosis Movement of large material◦ Particles◦ Organisms◦ Large molecules Movement is into the cellsTypes of Endocytosis◦ Bulk-phase (nonspecific)◦ Receptor-mediated (specific)
  59. 59. Process of Endocytosis Plasma membrane surrounds material Edges of membrane meet together Membranes fuse to form vesicle
  60. 60. Exocytosis Reverse of endocytosis Cell discharges material
  61. 61. References Grey’s textbook of human anatomy40th edition Guyton and Hall textbook of medicalphysiology 12th edition Ganong’s textbook of medical physiology 21stedition Human physiology volume-1,Dr. C.CChatterjee Text book of human histology, Inderbir singh http://www.biologymad.com/resources http://biology.about.com/od/molecularbiology http://rarediseases.about.com/od/rarediseasesz/a/030505.htm