cell bioly

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  • Created by: Sona16
  • Created on: 13-05-21 14:16
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  • cell theory
    • all living organisms are made up of cells
    • introduction to cell
      • cell size and growth
        • as cells increase in size, their surface area: volume ratio decreases
        • multicellular organism are joined together by cells. these cells can become specialised
        • specialized cells are organized into tissue and organs
        • a tissue is a group of similar cells that are specialized to perform a specific function
        • an organ is a collection of different tissue which performs a specialized function
      • stem cells
        • stem cells are undifferentiated cells present in all multicellular organisms
        • By division they are capable of giving riser to more cells of the same type
        • From these, differentiated cells are formed
        • the capacity of stem cells to divide  and differentiate slong diffrent pathways : allows for embyological development, makes stem cells suitable for theraputic uses
        • embryological development
          • all cells in a multicellular organisms contain the same genetic code, ad they are produced from the same original parent cell.
          • cell differentiation takes place when some genes and not others are expressed in a cell's genome. e.g. to make a muscle cell, the genes involved in creating the muscle cell is switched on and other genes are not needed and are not activated
        • embryonic stem cells are capable of continual cell division and developing into all cell types of adult organism.
        • adult stem cells; undiffrentiated cells is capable of cenll divisions which gives rise into a limited range of cells. it occurs in the growing and in adult body, within most organs, they replace dead or damages cells.
      • stem cell uses
        • sorce of treatment is embryonic stem cell.
          • treatment: SC are treated that they can divide and differentiate to become retina cells and it becomes attached to improve central vision
      • use of stem cell
        • leukemia
          • the effect: cancer of the blood or bone marrow, resulting in diseased white blood cells that dosent function properly
          • souce of stem cells: adult stem cells- hematopoietic stem cells harvested from bone marrow or umbilical cord blood.
          • treatment: chemotherapy and radiotherapy are used to destroy the diseased white blood cells. HSCs are transplanted into bone marrow, where they can differentiate to form new healthy white blood cells.
      • measuring microscopic objects
        • the size of cells, or components of cells, can be calculated given the amount of magnification and a scale drawing of the object
        • I= size of image, A= actual size of the object being measured, M= magnification. M=I/A; A=I/M & I=A x M.
    • cells are the smallest unit of life
    • existing cells have become other cells
    • questioning cell theory
      • there are a few multinucleate organs and organisms that are not divided into seperate cells called acellular
      • the pin mould rhizopus, in which the body consists of fine, thread like structure called hyphae
      • the striped muscle fibre that makes up the skeletal muscle of mammals.
      • the internodal cells of the giant alga nitella are also multinucleate.

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