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What is the lysosome pH normally?

Discussion in 'MCAT Study Question Q&A' started by engineeredout, Jun 15, 2008.

  1. engineeredout

    engineeredout 7+ Year Member

    May 11, 2008
    Q: When a primary lysosome fuses with a food vesicle to become a secondary lysosome:

    A: its pH drops via active pumping of protons into its interior.

    The explanation for the question says that the low pH is required in order to activate the digestive enzymes.

    I thought the lysosome normally has a pH around 5. Does the pH have to drop even further than that, or is 5 the pH that is required to activate the enzymes? If so, does it just float around with a neutral pH the rest of the time?

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  3. cwfergus

    cwfergus 7+ Year Member

    May 12, 2008

    The pH of a lysosome is yes, usually around 5 which is acidic.

    So these hydrolytic enzymes that are in the lysosomes, are what is keeping the pH this low. SO, when it fuses with a vesicle, it pumps it's low pH (H+s) to the vesicle, digesting it. So yes, if it fuses with a vesicle, the pH will drop in that vesicle

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