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Cell membrane function and cell cycle

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About cell membrane function and Cell cycle

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Cell membrane function and cell cycle

  1. 1. Outline •Fluid Mosaic Model •Function of Cell membrane •Membrane Proteins •Cell junction •Cell signaling •Cell Cycle
  2. 2. •Protection •Communication •Selectively allow substances in •Respond to environment •Recognition
  3. 3. •Transport •Receptors •Enzymes •Signal Transducers •Support
  4. 4. Plasma Membrane Proteins
  5. 5. Permeability of the Cell Membrane
  6. 6. Diffusion The passive movement of molecules from a higher to a lower concentration until equilibrium is reached. It also called Passive transport
  7. 7. Active Transport
  8. 8. •Exocytosis---Cellular secretion •Endocytosis— Phagocytosis— “Cell eating” Pinocytosis– “Cell drinking” Receptor-mediated endocytosis-specific particles, recognition.
  10. 10. PHAGOCYTOSIS Phagocytosis 1 Phagocytosis 2
  13. 13. Definition and Classification of cell junction Cell junction is the connection between the neighbouring cells or the contact between the cell and extracellular matrix. It is also called membrane junction. Cell junction are classified into three types a-Occluding junction or Tight junction b-Communicating junction or Gap junction c-Anchoring junction.
  14. 14. Tight Junction Tight Junction- occluding junctions / zonulae occludens - zonula occludens), are the closely associated areas of two cells whose membranes join together forming a virtually impermeable barrier to fluid.  A type of junctional complex present only in vertebrates. Gap Junction Gap junctions are clusters of intercellular channels that allow direct diffusion of ions and small molecules between adjacent cells. At gap junctions, the intercellular space narrows from 25 nm to 3 nm.
  15. 15. CELL SIGNALING  General Principles of Cell Signaling  signaling cell => signaling molecule binds to receptor molecule on target cell Signaling Distances: => Four Types of Signaling F.16-3  Endocrine  Paracrine  Autocrine  Contact Dependent
  16. 16. Cell Division The process of reproduction or formation of new cell from pre-existing cell is referred to as cell division Cell cycle The period in one cycle of cell division is completed is called cell cycle
  17. 17. INTERPHASE  Interphase can be subdivided into G1, S and G2 phases.  In yeast “Start” is at the end of G1; at this point the cell is committed to DNA synthesis.  In mammals, this is called the “restriction point”. This point late in G1 is a “checkpoint”; a cell will exit the cell cycle if certain requirements to proceed to synthesis are not met.  A second restriction point occurs in G2 before entry into mitosis. Interphase M Interphase M Interphase G1 S G2 M G1 S G2 M G1 S G2
  18. 18. INTERPHASE: G1  Events during G1  Cell growth  Preparation of chromosomes for replication  Duplication of cellular components  G1 checkpoint (or restriction point); cell commits to division or exits from cell cycle
  19. 19. INTERPHASE: S PHASE  DNA replication  Duplication of the centrosome  The centrosome is located near the nucleus of the cell and contains the microtubule organizing center MTOC in animal cells. It contains two centrioles that migrate to the poles before cell division and serve to organize the spindle.
  20. 20. INTERPHASE: G2  Cell growth  Checkpoint (restriction point) for entry into M phase
  21. 21. M PHASE  Cell division (mitosis or meiosis for germ cells)  Can be subdivided into four subphases:  Prophase  Metaphase  Anaphase  Telophase  Factors that influence M phase entry  Cellular Mass  Growth Rate  Time (During early embryogenesis, divisions may proceed rapidly, essentially alternating M and S phases, with little growth between them.)  Completion of DNA Replication