Endocytosis

[vivatix]

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The solutions say the answer is A.


I get that endocytosis would not happen anymore. But from my understanding, polypeptide hormones bind to extracellular receptors and result in a secondary messenger cascade resulting in signal transduction. I didn’t think that they actually enter the cell in endosomes. Can someone clarify?


I chose D because I was thinking that if a molecule requires endocytosis to enter the cell, then we know that it must be a large, possibly hydrophilic or charged molecule which can’t easily cross the cell membrane. So, if endocytosis can’t happen now, then the other potential way to get this molecule into the cell is to use other channels/carriers (which the cell might have to make) or make that molecule internally to compensate for the fact that it can’t be brought in from the outside – both possibilities requiring an increase in ATP consumption.

Can someone go over all the choices and discuss them? Thanks!

 

[vivatix]

 

[edgerock24]

View attachment 196733

My typical non-bio major way of answering this question:
Clathrin leads to endocytosis. If it is inactivated, less endocytosis will happen. Less stuff will enter the cell. Now, lets look at our answers:

A: sounds OK. Since less stuff can enter the cell, there will be reduced delivery inside of the cell. Sure.
B and C: I'd eliminate these two because, generally speaking, there won't likely be monumental increases in much of anything if endocytosis is limited.
D: Seems like a trick answer to me (sorry, don't have a good explanation here).

All in all, A seems like the best answer after we make the science a little more simple.

Perhaps some bio majors can add some more reasoning that may be more helpful.

 

[vivatix]

Thanks!

But I thought that polypeptide hormones don't actually enter the cell so inactivation of clathrin should not really affect this. These hormones bind to the extracellular receptors.