2. cell


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2. cell

  1. 1. CELL S.S.MOORTHY SEMENCHALAM M.Sc. Comm Health (Occ Health) UKM B.HSc. Nursing (Aust) Dip Med Sc. (Moh)11/26/12 DNM 100 1
  2. 2. Learning Outcomes At the end of this session, the students will be able to: • Define cell and organelle • State the function of each organelles • List generalizes cells – Nucleus – Mitochondria – Golgi apparatus – Ribosome – Lysosome – Rough and smooth endoplasmic reticulum • Understand the cell membrane transportation across cell membrane • Discuss cell division – mitosis and meiosis11/26/12 DNM 100
  3. 3. Cell Theory – 4 basic Concepts• Cell is the basic unit of structure and function of all living organisms• The activity of an organism depends on both the individual and collective activity of its cells• The biochemical activities of cells are determined by their specific sub-cellular structures• Continuity of life has a cellular basis (cells come from cells) 11/26/12 DNM 100
  4. 4. Structure of a Generalized Cell11/26/12 DNM 100
  5. 5. TerminologyThe Cytoplasm is the viscous, semi-fluid (gel-like) matter betweenthe cell membrane and the nucleusThe aqueous or watery component of the cytoplasm is the Cytosol,which includes ions and soluble macromoleculesThe insoluble constituents of the cytoplasm include the Organellesand the CytoskeletonThe space outside cells is called the Interstitium. The extracellularfluid is called Interstitial fluid (containing sugars, amino acids,vitamins, hormones, salts, and waste products. 11/26/12 DNM 100
  6. 6. Plasma Membrane (Cell Membrane)• Every cell is surrounded by a cell membrane• It separates the cell’s cytoplasm from its external environment• It also regulates the passage or transport certain molecules in and out of the cell, while preventing the passage of others (“selective semi-permeable membrane”) 11/26/12 DNM 100
  7. 7. Plasma Membrane (Cell Membrane) • Cell membrane is made of protein and lipid (fatty substance) molecules, which arranged in a double layer Head (polar) - Hydrophilic -Phospolipid Cell membrane Tails (nonpolar) - Hydrophobic - 11/26/12 DNM 100
  8. 8. Nucleus• The largest organelles• It contains the body’s genetic material, which directs the activities of the cell called genes (chromosomes)• Human somatic cells have 46 chromosomes, 23 inherited from each parent. 11/26/12 DNM 100
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  10. 10. Mitochondria• The ‘powerhouses’ of the cell• Generate most of the ATP ( adenosin triphosphate ) cellular energy• Active cells, such as those found in the muscles, liver, and kidneys, have a large number of mitochondria (high rate ATP usage)11/26/12 DNM 100
  11. 11. Golgi apparatus• Consists of stacks of closely folded flattened membranous sacs• It is present in all cells but is larger in those that synthesis and export protein11/26/12 DNM 100
  12. 12. Ribosomes• Tiny granules composed of RNA and protein• Synthesised protein from amino acid• Free ribosomes make protein for use within the same cell11/26/12 DNM 100
  13. 13. Endoplasmic Reticulum (ER)• Two types: 1) Smooth ER 2) Rough ER• Smooth ER – synthesises lipids and steroid hormones. It is also associated with the detoxification of some drugs• Rough ER – studded with ribosomes11/26/12 DNM 100
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  15. 15. Lysosomes• Formed by the Golgi apparatus• Contain a variety of enzymes involved in breaking down large molecules (e.g. carbohidrate and protein) into smaller particles that are either recycled or expelled from the cell as waste material• Intracellular digestive system ( destroy cellular debris from damaged cells)11/26/12 DNM 100
  16. 16. Cell Membrane TransportPassive Transport - requires no ATP (energy) input Diffusion Simple Diffusion Facilitated Diffusion Osmosis FiltrationActive Transport - metabolic energy ATP required Primary Active Transport Secondary Active TransportVesicular Transport Exocytosis Endocytosis 11/26/12 DNM 100
  17. 17. Passive Transport: Diffusion Diffusion is a physical process whereby molecules of gases, liquids, or solid particles scatter themselves evenly through a medium. Molecules are in constant motion (kinetic energy) and move around in a random fashion, colliding with other molecules and/or walls of the container.Molecules move from areas where they are in higherconcentration to areas where their concentration is lower 11/26/12 DNM 100
  18. 18. Passive Transport: Diffusion Molecules move from areas where they are in higher concentration to areas where their concentration is lower11/26/12 DNM 100
  19. 19. Passive Transport: Diffusion The driving force for diffusion is the kinetic energy of the particles The speed or rate of diffusion is influenced by: Molecular size (the smaller, the faster) Temperature (the warmer, the faster)11/26/12 DNM 100
  20. 20. Cell Membrane – Semi-PermeableThe plasma membrane is a selectively permeable barrier. It only allows “selected” substances to pass through. 11/26/12 DNM 100
  21. 21. Passive Membrane Transport: Facilitated Diffusion Some molecules, combine with protein carriers move through transmembrane protein channels11/26/12 DNM 100
  22. 22. Passive Membrane Transport: Facilitated Diffusion11/26/12 DNM 100
  23. 23. Passive Transport: OsmosisOsmosis - movement of water across a semi permeable membrane. *Driven by a difference in solute concentrations on the two sides of the membrane.Osmolarity- Total concentration of solute particles in a solution 11/26/12 DNM 100
  24. 24. Effect of Membrane Permeability on Diffusion and Osmosis – Membrane Permeable to Solute and Water11/26/12 DNM 100
  25. 25. Solution tonicityIsotonic – solutions with the same solute concentration as the cytosolHypertonic – solutions having greater solute concentration than the cytosolHypotonic – solutions having lesser solute concentration than the cytosol11/26/12 DNM 100
  26. 26. Hypotonic Isotonic Hypertonic11/26/12 DNM 100
  27. 27. Passive Transport: FiltrationThe movement of water and solutes across a membrane due to some mechanical force, such as blood pressure and gravityPressure gradient pushes solute-containing fluid from a higher-pressure area to a lower-pressure area Filtration also occurs in the kidney (glomerulus). 11/26/12 DNM 100
  28. 28. Active Transport•Process whereby molecules move across the cellmembrane from an area of lower concentration toan area of higher concentration (against theconcentration gradient)•Requires the high energy chemical compoundATP which is supplied by cell metabolism(adenosine triphosphate)11/26/12 DNM 100
  29. 29. Vesicular Transport• Transport of large particles, macromolecules, and fluid across plasma and intracellular membranes – Exocytosis – (Exo = out) – moves substance from the cell interior to the extracellular space – Endocytosis – (Endo = in) – moves substance from the outside into the intracellular space - Phagocytosis (cell eating) – substances engulfed by the cell membrane are within particles - Pinocytosis (cell drinking) – substances engulfed by the cell membrane are in solution11/26/12 DNM 100
  30. 30. Exocytosis Hormone secretion, neurotransmitter release, mucus secretion, ejection (excretion) of wastes11/26/12 DNM 100
  31. 31. Endocytosis - Phagocytosis bacteria, cell debris Phagocytosis – pseudopods extend, engulf solids, and bring them into the cell (phagosome may fuse with a lysosome → phagolysosome)11/26/12 DNM 100
  32. 32. Endocytosis - Pinocytosis Pinocytosis – fluid-phase endocytosis – cell membrane invaginates (infolds) and brings extracellular fluid and solutes into the cell11/26/12 DNM 100
  33. 33. Principle of cell division• A cell has its own life span• Eventually cells damage, get worn out and die. They are replaced by a process of cell division for growth, repair & replacement.• Humans have 46 chromosomes (23 pairs). – 22 pairs somatic (body) chromosomes – 1 pair is sex chromosomes.11/26/12 DNM 100
  34. 34. Principle of cell division• Nuclear division involves 5 main phases:1) INTERPHASE- Cell is engaged in metabolic activity and prepare for mitosis / meiosis2) PROPHASE- Chromatin in the nucleus begins to condense & become visible. Centrioles begin to move to opposite ends of the cells3) METAPHASE- Spindle fibers align the chromosomes along the middle of the cell nucleus4) ANAPHASE- Paired chromosomes separate at the kinetochores and move to opposite side of the cell5) TELOPHASE- Chromatid arrive at the respective poles, and cytokinesis (partitioning) begins11/26/12 DNM 100
  35. 35. Cell division: Mitosis• Mitosis is a somatic (body) cell division• A cell undergoes nuclear division and produce 2 identical daughter cells.• Each daughter cell has the same number and kind of chromosomes as the original cell (46)• Somatic cell division replaces dead or injured cells and adds new ones for tissue growth. 11/26/12 DNM 100
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  37. 37. Cell division: Meiosis• Meiosis is a reproductive cell division( eggs & sperm ).• A cell undergoes nuclear division and produces 4 identical daughter cells.• Each daughter cell has half of chromosomes of the original cell (23)• Reproductive cell division produces gametes (sperm and ova)• Two stages: Meiosis I and Meiosis II 11/26/12 DNM 100
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  39. 39. QUESTIONS PLEASE..11/26/12 DNM 100