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  1. 1. The Cellular Level of Organization Dr. Nishkruti R. Mehta Associate Professor, Head, Department of Pharmacology, Khyati College of Pharmacy
  2. 2. The purpose of the chapter is to: 1. Introduce the Cell and parts of a cell 2. Discuss the importance of the plasma membrane 3. Discuss the components of the cytoplasm 4. Compare and contrast mitosis and meiosis 5. Understand the effects aging has on the cell Introduction
  3. 3. What is cell ?  The structural and functional of the body is called Cell.  The smallest unit that can live on its own and that makes up all living organisms and the tissues of the body.  A cell has three main parts: the cell membrane, the nucleus, and the cytoplasm.  The cell membrane surrounds the cell and controls the substances that go into and out of the cell.  The nucleus is a structure inside the cell that contains the nucleolus and most of the cell’s DNA. It is also where most RNA is made.  The cytoplasm is the fluid inside the cell. It contains other tiny cell parts that have specific functions, including the Golgi complex, the mitochondria, and the endoplasmic reticulum. The cytoplasm is where most chemical reactions take place and where most proteins are made. The human body has more than 30 trillion cells.
  4. 4. The cell can be subdivided into 3 parts:     1. Plasma (cell) membrane 2. Cytoplasm Cytosol Organelles 3. Nucleus Chromosomes Genes Parts of a Cell
  5. 5. Parts of a Cell
  6. 6. The cell can be subdivided into 3 parts:     1. Plasma (cell) membrane 2. Cytoplasm Cytosol Organelles 3. Nucleus Chromosomes Genes Parts of a Cell
  7. 7. The plasma membrane is a flexible yet sturdy barrier that surrounds and contains the cytoplasm of the cell The Plasma Membrane
  8. 8. Two types of membrane proteins are  Integral (also called transmembrane) proteins  Peripheral proteins Membrane Proteins
  9. 9.  Membrane proteins can serve a variety of functions  The different proteins help determine many of the functions of the cell membrane Functions of Membrane Proteins
  10. 10. Membranes are fluid structures because most of the membrane lipids and many of the membrane proteins move easily in the bilayer  Membrane lipids and proteins are mobile in their own half of the bilayer Cholesterol serves to stabilize the membrane and reduce membrane fluidity Membrane Fluidity
  11. 11. Plasma membranes are selectively permeable  The lipid bilayer is always permeable to small, nonpolar, uncharged molecules  Transmembrane proteins that act as channels or transporters increase the permeability of the membrane  Macromolecules are only able to pass through the plasma membrane by vesicular transport Membrane Permeability
  12. 12. A concentration gradient is the difference in the concentration of a chemical between one side of the plasma membrane and the other An electrical gradient is the difference in concentration of ions between one side of the plasma membrane and the other Together, these gradients make up an electrochemical gradient Gradients Across the Plasma Membrane
  13. 13. Transport processes that move substances across the cell membrane are:  Passive processes    Simple diffusion Facilitated diffusion Osmosis  Active processes   Active transport Vesicular transport Transport Across the Plasma Membrane
  14. 14. Transport Processes Interactions Animation:  Transport Across the Plasma Membrane You must be connected to the Internet and in Slideshow Mode to run this animation.
  15. 15. Passive Processes
  16. 16. Diffusion is influenced by: 1. Steepness of the concentration gradient 2. Temperature 3. Mass of diffusion substance 4. Surface area 5. Diffusion distance Simple Diffusion
  17. 17. Transmembrane proteins help solutes that are too polar or too highly charged move through the lipid bilayer The processes involved are:  Channel mediated facilitated diffusion  Carrier mediated facilitated diffusion Facilitated Diffusion
  18. 18. Channel Mediated Facilitated Diffusion
  19. 19. Carrier Mediated Facilitated Diffusion
  20. 20. Diffusion: A Comparison
  21. 21. Osmosis  The net movement of a solvent through a selectively permeable membrane from an area of high concentration to an area of low concentration
  22. 22. Tonicity of a solution relates to how the solution influences the shape of body cells Tonicity
  23. 23. Active Processes
  24. 24. Primary Active Transport  Energy derived from ATP changes the shape of a transporter protein which pumps a substance across a plasma membrane against its concentration gradient
  25. 25. Secondary Active Transport  Energy stored (in a hydrogen or sodium concentration gradient) is used to drive other substances against their own concentration gradients
  26. 26. Active Transport in Vesicles: Receptor- mediated Endocytosis
  27. 27. Active Transport in Vesicles: Phagocytosis
  28. 28. Active Transport in Vesicles: Bulk Phase Endocytosis (Pinocytosis)
  29. 29. Active Transport in Vesicles: Exocytosis & Transcytosis  Exocytosis – membrane- enclosed secretory vesicles fuse with the plasma membrane and release their contents into the extracellular fluid  Transcytosis – a combination of endocytosis and exocytosis used to move substances from one side of a cell, across it, and out the other side
  30. 30. A Comparison of Transport Types
  31. 31. A Comparison of Transport Types
  32. 32. Parts of a Cell: Cytoplasm
  33. 33. Cytosol is also known as the intracellular fluid portion of the cytoplasm Organelles are the specialized structures that have specific shapes and perform specific functions Cytoplasm
  34. 34. Cytoskeleton
  35. 35. Centrosome/Centriole s
  36. 36. Cilia and Flagella
  37. 37. Cilia and Flagella
  38. 38. Ribosomes
  39. 39. Endoplasmic Reticulum
  40. 40. Golgi Complex
  41. 41. Lysosomes
  42. 42. Peroxisomes are structures that are similar in shape to lysosomes, but are smaller and contain enzymes that use oxygen to oxidize (break down) organic substances Peroxisomes
  43. 43. Proteasomes  Proteasomes are barrel-shaped structures that destroy unneeded, damaged, or faulty proteins by cutting long proteins into smaller peptides
  44. 44. Mitochondria
  45. 45. Nucleus
  46. 46. The nucleus contains the cell’s hereditary units, called genes, which are arranged in chromosomes Nucleus
  47. 47. Gene Expression
  48. 48. Transcription occurs in the nucleus and is the process by which genetic information encoded in DNA is copied onto a strand of RNA to direct protein synthesis Protein Synthesis: Transcription
  49. 49. Protein Synthesis: Translation  Translation occurs in the nucleus and is the process of reading the mRNA nucleotide sequence to determine the amino acid sequence of the newly formed protein
  50. 50. Protein Synthesis During Transcription
  51. 51. Cell division is a process by which cells reproduce themselves  Cell cycle Cell Division
  52. 52. G1phase S G2phase Interphase
  53. 53. During prophase chromatin condenses into chromosomes Mitotic Phase: Prophase
  54. 54. During metaphase centromeres of chromosomes line up at the metaphase plate Mitotic Phase: Metaphase
  55. 55. During anaphase centromeres of chromosomes split and sister chromatids move toward opposite poles of the cell Mitotic Phase: Anaphase
  56. 56. During telophase the mitotic spindle dissolves, chromosomes regain their chromatin appearance, and a new nuclear membrane forms Mitotic Phase: Telophase
  57. 57. During cytokinesis a cleavage furrow forms and eventually the cytoplasm of the parent cell fully splits  When this is complete, interphase begins Cytokinesis
  58. 58. 3 possible destinies: 1. Remain alive and functioning without dividing 2. Grow and divide 3. Die Control of Cell Destiny
  59. 59. Reproductive Cell Division: Meiosis I
  60. 60. Reproductive Cell Division: Meiosis II
  61. 61. Cellular Diversity
  62. 62. As we age:  Our cells gradually deteriorate in their ability function normally and in their ability to respond to environmental stresses  The numbers of our body cells decreases  We lose the integrity of the extracellular components of our tissues Free radicals Aging and Cells