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Functions of Vacuoles

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Functions of Vacuoles

Postby missgates » Mon Oct 27, 2008 10:58 pm

I have a project for biology and i have to write the function of the organelles in an animal cell.
I've gotten the meaning for vacuoles but am still having a hard time understanding it. If someone could please explain the funtion that would be helpful.
Thank you :D
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Postby MrMistery » Mon Oct 27, 2008 11:53 pm

there are no vacuoles in animal cells. Vacuoles are only found in photosynthetic organisms, some protozoans and fungi. So you don't need to write down vacuoles.
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Re:

Postby missgates » Tue Oct 28, 2008 12:14 am

thank you very much!
MrMistery wrote:there are no vacuoles in animal cells. Vacuoles are only found in photosynthetic organisms, some protozoans and fungi. So you don't need to write down vacuoles.
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Re:

Postby wheel » Wed Oct 29, 2008 4:19 am

MrMistery wrote:there are no vacuoles in animal cells. Vacuoles are only found in photosynthetic organisms, some protozoans and fungi. So you don't need to write down vacuoles.


I thought there are temporary vacuoles in non-photosynthetic cells too. For example, the food vacuoles formed when the plasma membrane cleaves inward to form a temporary vacuole containing the food particles. And, there are many other temporarily-formed vacuoles called vesicles in a cell. We have pinocytotic vesicles and phagocytotic vesicles known as phagosomes. However, the vacuoles (large central vacuoles) in plant cells are always much bigger than the temporary vacuoles in animal cells.

If I am not mistaken, these temporary vacuoles are also considered a type of vacuoles.

That's what I know. Do correct me if I got wrong.
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Postby MrMistery » Wed Oct 29, 2008 4:51 am

Until about 30-40 years ago, nobody really knew much about how intracellular vesicular traffic really worked. Thus, they designated cellular structures by their shape in the microscope. That is why old books make confusions for such term as that of vacuole. Any modern cellular biology course will tell you that vacuoles are the counterparts of lysosomes. Actually, they are pretty much the same thing, only they have different sizes. They both employ the mannose-phosphate tag, the targeting sequences are similar, they both use proton pumps to generate a low pH etc. Of course, they have many different functions and proteins because they evolved for different purposes, but for the most part they are very similar. You will never find both lysosomes and vacuoles in the same cell. It just makes no sense.
About vesicles: never, ever confuse vesicles with vacuoles. Vesicles are for transport, they have much smaller sizes and are used between all compartments of the endomembrane system (ER, Golgi, Plasma membrane and lysosomes).
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Postby wheel » Fri Oct 31, 2008 11:52 am

So, can we say animal cells have vacuole because of the presence of temporary vacuole? Or, does the term 'vacuole' only refer to the central vacuole in plant cells?

I know that there are many confusions in the field of biology. And even biologists have disagreement among themselves. So, is this question about vacuole one of the controversial problems in biology?
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Postby MrMistery » Sat Nov 01, 2008 6:33 am

Its cotroversial if you want to make it.
"Temporary vacuoles" as you call them are not vacuoles. Food vacuoles are referred to by that term for historic reasons. However, in cell biology today it is pretty clear what that the vacuole is that "central vacuole" from plants (I don't really like that term, because it doesn't have to be in the center of the cell). Some zoologists still say animal cells have vacuoles, because some are not up-to-date with a vacuole actually means in present days...

Hope this helps clear things up
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Re:

Postby IAreAsian » Wed Nov 12, 2008 7:31 am

MrMistery wrote:there are no vacuoles in animal cells. Vacuoles are only found in photosynthetic organisms, some protozoans and fungi. So you don't need to write down vacuoles.


There ARE vacuoles in animal cells, they are just not as big or have much of a function in animal cells.
As for the function of vacuoles
Removing unwanted structural debris
Isolating materials that might be harmful or a threat to the cell
Containing waste products
Maintaining internal hydrostatic pressure or turgor within the cell
Maintaining an acidic internal pH
Containing small molecules
Exporting unwanted substances from the cell
from wikipedia.
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Postby MrMistery » Thu Nov 13, 2008 3:29 am

No there are not. Check any cellular biology textbook written after the year 2000. I recommend Alberts et al., but for simple things like this pretty much any book will do.
And wikipedia is not always the most reliable source. For example vacuoles do not export anything from the cell, because plant cells are unable to carry out exocytosis.
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