Cell biology ppt

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Cell biology ppt

  1. 1. CELL BIOLOGY BY: DR. JYOTISH KUMAR JHA DEPARTMENT OF ORAL MEDICINE AND RADIOLOGY
  2. 2. CONTENTS :            Definition: Characteristics of cells: Structure of cells Structure of cell membrane: Applied physiology of cell membrane: 1)Cytoplasm: 2)Rough Endoplasmic Reticulum: 3)Smooth Endoplasmic Reticulum: 4)Golgi apparatus: 5)Lysosomes: 6)Perioxisomes:
  3. 3.           7)Mitochondria : 8)Ribosomes: Nucleus Function of nucleus DNA RNA TRANSCRIPTION AND TRASNSLATION CELL DIVISION TYPES OF CELL DIVISION MITOSIS
  4. 4.  CELL CYCLE  DIFFERENCE BETWEEN MITOSIS AND      MEIOSIS LIST OF CHROMOSOMAL ABNORMALITIES CHROMOSOMAL ABERRATION APOPTOSIS CELL JUNCTON VIRUS ENTRY TO CELL
  5. 5.  TERM WAS COINED BY” ROBERT HOOK” (1635-1703)  DEFINED AS STRUCTURAL AND FUNCTIONAL UNIT OF LIFE
  6. 6. GENERAL CHARACTERISTICS OF CELL • Needs nutrition & oxygen • Eliminates carbon dioxide & other metabolic wastes • Shows immediate response to the entrance of invaders • Reproduces by division
  7. 7. STRUCTURE OF CELL
  8. 8.  Each cell is formed by a cell body and a membrane covering the cell body known as cell membrane or plasma membrane  The cell body has two parts namely the nucleus and the cytoplasm surrounding the nucleus.  Thus the structure of a cell is studied under 3 headings… I. Cell membrane II. Cytoplasm III. nucleus
  9. 9. CELL MEMBRANE  Protective sheath covering the cell body Separates the fluid outside the cell called extracellular fluid(ECF) and the fluid inside the cell called intracellular fluid(ICF) COMPOSITION OF CELL MEMBRANE 1. PROTEINS(55%) 2. LIPIDS(40%) 3. CARBOHYDRATES(5%)
  10. 10. STRUCTURE OF CELL MEMBRANE THREE PROPSED MODELSW ARE 1. Danielli-Davson model 2. Unit membrane model 3. The fluid mosaic model THE CELL MEMBANE is a three layered membrane. MICROSCOPIC STUDY REVEALS Central electron-lucent layer called LIPID LAYER formed by lipid protein • MAJOR LIPIDS PRESENT ARE 1. PHOSPHOLIPIDS 2. CHOLESTROL functional significance of this layer is that it forms a semi permeable membrane and allows only fat soluble substances to pass through ie oxygen, carbon dioxide &alcohol 2 electron-dense layer one on either side of central layer called PROTEIN LAYER formed by protein substances. MAJOR PROTEIN PRESENT ARE 1. Integral Protein 2. Peripheral Protein
  11. 11. Functional significance of protein layer 1. Integral protein provide the structural integrity of cell membrane 2. Channel protein- for diffusion of water soluble substances like glucose and electrolyte 3. Carrier protein 4. Receptor protein 5. Antigen
  12. 12. APPLIED PHYSIOLOGY ON CELL MEMBRANE  LIPID soluble material in the ECE, when come in contact with cell membrane get dissolved in the oily cell membrane then enter the cytoplasm. Thus lipid soluble drugs easily pass the bloodbrain barrier(BBB)  In the cell membrane of fungus ergosterol is present instead of cholestrol, drugs are present which get attached with ergosterol and damage them and thus the fungal cell membrane is damaged and last death  such drugs are AMPHOTERECIN B. AMB used against fungal infection
  13. 13. 1. CYTOPLASM  ORGANELLES IN CYTOPLASM 1. ENDOPLASMIC RETICULUM 2 TYPES rough endoplasmic reticulum smooth endoplasmic reticulum function of rough endoplasmic reticulum 1. synthesis of protein 2. degradation of worn out organelles function of smooth endoplasmic reticulum 1. synthesis of lipids and steroids 2. storage and metabolism of calcium 3. degradation of toxic substances in liver
  14. 14.  GOLGI APPARATUS present in all cells except red blood cells 2. has two faces or ends cis face and trans face, cis face is close to endoplasmic reticulum and trans face near the cell membrane function of golgi apparatus • processing, labelling and delivery of proteins and lipids in different parts of cell 1.
  15. 15.  LYSOSOMES membrane bound vesicular organelles found throughout the cytoplasm 2. Formed by golgi apparatus 3. Enzymes synthesized in RER are processed and packed in the form of vesicles in the golgi apparatus 4. Then these vesicles are pinched off from golgi apparatus and become the lysosomes 1.
  16. 16.  TYPES OF LYSOSOMES 1. PRIMARY LYSOSOMES -- one that is pinched off from the golgi apparatus and is inactive 2. SECONDARY LYSOSOMES – a active lysosome formed by fusion of primary lysosome with phagosome or endosome
  17. 17. FUNCTION OF LYSOSOMES 1. Degradation on macromolecules like bacteria 2. Degradation of worn out organelles 3. Secretory function
  18. 18. PEROXISOMES  FUNCTION OF PEROXISOMES 1. Degradation of toxic substances like hydrogen 2. 3. 4. 5. 6. peroxide – present in liver cells which is a major organ for detoxification Oxygen utilization Breakdown of excess fatty acids Acceleration of gluconeogenesis from fats Degradation of purin to uric acid Role in the formation of myelin and bile acids
  19. 19. CENTROSOME AND CENTRIOLES
  20. 20.  Situated near the centre of the cell close to the nucleus  Responsible for the movement of chromosomes during cell division
  21. 21. MITOCHONDRIA
  22. 22.  Rod like oval structure  Bilayered membranous organelle  Outer membrane smooth and encloses the contents of mitocondria  Inner membrane folded in the form of shelf called cristae  Cristae contains many enzymes and other protein molecules which are involved in respiration and synthesis of ATP  Move freely in cytoplasm and capable of self reproduction
  23. 23. FUNCTION OF MITOCONDRIA  Production of energy– called POWER HOUSE OF CELL – required for cellular function – produced during oxidation of digested food particles like proteins,crbohdrates and lipids  Synthesis of ATP  apoptosis
  24. 24. RIBOSOMES  Granular and small dot like structure  Made up of proteins(35%) and RNA(65%) FUNCTION OF RIBOSOMES  SYNTHESIS OF PROTEIN mRNA passes genetic code for protein synthesis from nucleus to ribosome Ribosomes arrange the amino acids into small units of protein Ribosomes attached with ER are involved in protein synthesis like enzymatic protein,harmonal protein and proteina of cell membrane
  25. 25. There are two types of cells: 1) Prokaryotic Cells 2) Eukaryotic Cells
  26. 26. These are two distinct types of cells with STRUCTURAL differences. Prokaryotes Bacteria Eukaryotes Animal Plant
  27. 27. Traits of Prokaryotes: (pro-care-ee-ohts) 1. They do not have a nucleus, and their genetic material is not stored in the nucleus. 2. They have some organelles, but not many. 3. They are less complicated that eukaryotes. 4. All bacteria are prokaryotes.
  28. 28. Eukaryote Cell A more complex cell with a nucleus and many organelles.
  29. 29. Traits of Eukaryotes: (you-care-ee-othts) 1. They all have a nucleus where the genetic material of the cell is stored. 2. They have many organelles that work together to help the cell function.
  30. 30. COMPARISON OF PLANT AND ANIMAL CELL
  31. 31. NUCLEUS  located near centre of cell and is mostly spherical in shape. STRUCTURE OF NUCLEUS Covered by nuclear membrane and it encloses the structures called nucleo plasm and nucleolus NUCLEAR MEMBRANE  Double layered and porous in nature  Allows nucleoplasm to communicate with cytoplasm
  32. 32.  NUCLEOPLASM  Gel like ground substance of the nucleus  Contains large quantities of the genetic materials in the form of deoxyribonucleic acid(DNA) which form the gene  DNA made of thread like material known as chromatin
  33. 33.  NUCLEOLI o One or more nucleoli are present in each nucleus o Nucleolus contains ribonucleic acid(RNA) and some proteins similar to those found in ribosomes
  34. 34. FUNCTION OF NUCLEUS 1. Control of all the activities of the cell 2. Synthesis of RNA 3. Sending genetic instruction to the cytoplasm for protein synthesis through mRNA 4. Control of cell division through genes 5. Storage of hereditary information
  35. 35.  DNA  Genetic information of an organism is stored in genes of DNA  DNA forms the chemical basis of hereditary characters  Carrier for genetic information to the offspring  Contains instruction for the synthesis of proteins in the ribosome  DNA present in nucleus is responsible for synthesis of RNA
  36. 36.  RNA  Formed from DNA  Regulates the synthesis of proteins in the ribosome TYPES I. MESSENGER RNA (mRNA) carries genetic code of amino acid sequence for synthesis of protein from the DNA to cytoplasm
  37. 37.  TRANSFER RNA(tRNA) Responsible for decoding the genetic message present in mRNA RIBOSOMAL RNA(rRNA)  Present within ribosome and is responsible for the assembly of proteins from amino acids in the ribosomes
  38. 38. TRANSCRIPTION  Copying of genetic material from DNA to RNA  Transcription of genetic codes in nucleus formation of m RNA copying of message from DNA to m RNA m RNA enter the cytoplasm and activate the ribosome for protein synthesis
  39. 39. TRANSLATION  Process of protein synthesis in ribosomes ribosomes get attached to mRNA codons of mRNA recognized by complimentary base of tRNA called anticodons according to sequence of base of anticodon different amino acids transported from cytoplasm to ribosomes rRNA assemble the proteins from amino acids and attach to RER
  40. 40. BINARY FUSION BINARY FUSION BINARY FUSION MITOSIS MEIOSIS
  41. 41. The Cell Cycle
  42. 42. LIST OF CHROSOMAL ABNORMALITIES  a) b) c)  a. b. c. NUMERICAL ABNORMALITIES Aneuploidy Trisomic(2n+1) Monosomic(2n-1) STRUCTURAL ABNORMALITIES DOWN’S SYNDROME EDWARDS SYNDROME PATAU’S SYNDROME
  43. 43.  SEX CHROMOSOME DISORDER 1) KLINEFELTER’S SYNDROME 2) TURNER’S SYNDROME 3) FRAGILE X SYNDROME
  44. 44. CHROMOSOME ABERRATION  Useful marker for radiation injury  Observed in irradiated cells at the time of mitosis when the DNA condenses to form chromosome  If radiation exposure occurs after DNA synthesis(ie in G2 or mid or late S) only one arm of affected chromosome is broken  If radiation occurs before DNA replication(ie in G1 or early S) then break in both the arms
  45. 45. APOPTOSIS  Defined as programmed cell death under genetic control  A normal phenomenon and in essential for normal development of the body FUNCTIONAL SIGNIFICANCE  Main function is to remove unwanted cells without causing any stress or damage to the neighboring cells
  46. 46. SIGNIFICANCE 1) Vital role in cellular homeostasis 2) Useful for removal of a cell that is damaged by a virus of a toxin beyond repair 3) Essential event during the development and in adult stage
  47. 47. ROLE OF MITOCONDRIA IN APOPTOSIS  external or internal stimuli initiate apoptosis by activating the proteases CASPASES  Normally caspases suppressed by apoptosis inhibiting factor(AIF)  WHEN CELL RECEIVE APOPTOSIS STIMULI… mitochondria release two proteins 1. CYTOCHROME C 2. SECOND MITOCONDRIA-DERIVED ACTIVATOR OF CASPASES(SMAC)
  48. 48.  SMAC inactivates AIF  SMAC +AIF to form apoptosome activates CASPASES  CYTOCHROME C also facilitate caspase activation
  49. 49. APOPTOTIC PROCESS
  50. 50. CELL JUNCTION  It is the connection between the neighboring cells  THREE TYPES 1. OCCLUDING JUNCTION- prevent intercellular exchange of substances 2. COMMUNICATING JUNCTION-permits intercellular exchange of substances 3. ANCHORING JUNCTION-provide strength to the cells
  51. 51.  OCCLUDING JUNCTION  prevent movement of ions and molecule from one cell to another cell  TIGHT JUNCTION/ZONA OCCLUDENS belong to this category  Present in the apical margin of epithelial and endothelial cells in intestinal mucosa,walls of renal tubules,capillary wall
  52. 52. STRUCTURE OF TIGHT JUNCTION
  53. 53.  FUNCTION OF TIGHT JUNCTION 1. Holds the neighboring cell of tissues firmly for strength and stability 2. In epithelial and endothelial cells function as selective diffusion barrier between neighboring cells 3. Prevents lateral movement of integral proteins and lipids in cell membrane 4. In brain capillaries form blood-brain barrier allowing only lipid soluble drugs and steroids to pass through

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