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Please check my answers on orgenells

  1. Sep 14, 2004 #1
    R My defenitions of these orgenells correct :biggrin:
    VACUOLE = stores water and ions.
    LYSOSOME = produces enzymes to destroy bacteria.
    RIBOSOME = produces proteins.
    CYTOSKELETON = internal support system for cell.
    GOLGI BODY = packages proteins into vesicles.
    ENDOPLASMIC RETICULUM = transport system inside cell.
    NUCLEUS = control centre of cell.
    FLAGELLUM = long tail-like structure for cell locomotion.
    MITOCHONDRION = "powerhouse" of the cell (produces ATP).
    CHLOROPLAST = site of photosynthesis.
    AMYLOPLAST = stores starch in plant cell.
    CENTRIOLE = produces spindle fibres for mitosis.
    PROTOPLASM = supports all cell organelles.
    CELL MEMBRANE = semipermeable to control enter and exit of materials.
    NUCLEOLUS = produces ribosomes.
    CHROMOSOMES = genetic material in nucleus.
     
  2. jcsd
  3. Sep 15, 2004 #2

    Monique

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    Just by head
    lysosomes are the stomach of the cell, they don't produce enzymes: that is where the degradative enzymes are stored.
    Proteins travel in vesicles from the ER to the golgi, that is where sugars are added to the proteins after which they leave in vesicles again.
     
  4. Sep 15, 2004 #3
    i dont understand :confused:
     
  5. Sep 16, 2004 #4
    According to my Biology notes, golgi bodies are involved in the manufacure of lysosomes. I have no idea what lysosomes are.

    Also, I am assuming ER stands for Endoplasmic Reticulum which I think are engaged in making fats and proteins out of smaller molecules.
     
  6. Sep 17, 2004 #5

    Monique

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    Golgi bodies are processing factories where post-translational modification takes place of proteins.

    Proteins that have a certain signal sequence will be targeted to the lysosome, vesicles that bud from the golgi will fuse with the lysosome membrane and thus deliver the molecules to the right place.

    The rough endoplasmatic reticulum is where protein synthesis occurs: ribosomes attach and the protein is translated into the ER, here is where folding of the molecule will take place, after which it can be targeted to various organelles.
     
  7. Sep 17, 2004 #6
    From what I learned in my cell biology class, the rough ER is only where secretory and membrane proteins are synthesized, then they are sent to the Golgi where they are further modified. Non-secretory and non-membrane proteins are synthesized by free-floating ribosomes in the cytoplasm, because they need no further modification.

    The smooth ER is the site of lipid and steroid synthesis, and is also involved in detoxification.

    We also learned something, my memory is fading, about how a lysosome will be an early endosome which is just floating around, and then it matures into a late endosome (which is when the hydrolytic enzymes develop) and it can then either develop into a full lysosome or deliver its' enzymes to an existing lysosome. Monique, when you say vessicles from the Golgi to the lysosome, is this what you are talking about (endosomes?)
     
  8. Sep 17, 2004 #7

    Monique

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    Vesicles from the golgi apparatus can either localize to the lysosome, plasma membrane, or the secretory vesicles.

    You are right about the maturation of early endosomes, to late endosomes, towards being a lysosome. The way that this works is that the golgi apparatus will bud-off a vesicle. This vesicle contains a whole assortment of proteins (early endosome). Proteins destined for the lysosome contain a mannose-6-phosphate receptor, which will target it to its final destination. Proteins that contain a different targeting sequence will bud-off the vesicle, thus purifying the lysosomal proteins (late endosome). When only the lysosomal proteins are left, and the pH has become very acidic, does it become a true lysosome.
     
  9. Sep 19, 2004 #8
    Lysosomes destroy bacteria and dead cells
     
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