Prokaryotic Cell Question

[kneecoal]

Hi there!

I just had a quick question regarding some homework I'm doing for Gen. Bio. My professor asks really tricky question (a little annoying because now all I do is second guess mys answers), so I just wanted a little advice about one of the questions he's asking.

Here it is...

During a period of low water availability, which prokaryotic structure would protect a cell from dessication (drying out)?
A. pili
B. plasma membrane
C. nucleus
D. cell wall

Alright. So, I KNOW it isn't A or C. I'm struggling because I assumed glycocalyx would be an option, considering the main function of the glycocalyx is to trap water and help protect bacteria from drying out. Sweet. That's not a choice. I'm thinking the next logical answer would be B, the plasma membrane. The layer of phospholipids and proteins form a barrier between the CELL (what the question is referring to) and the external environment.

How does that sound? At the very least, if I get it wrong, I could probably fight the answer... right?

...right??

[JackBean]

Take it in that way, that if the cell membrane would be such great at protecting against environment, the bacteria would not need the cell wall.

[kneecoal]

Yeah, but the question doesn't specify bacteria. It simply states 'prokaryotic cell.' And, not all prokaryotes have cell walls (though nearly all of them do)- so I still don't see how 'cell wall' could then be a definite answer.

Blech. I shouldn't have to think this hard for a question worth only 3 points...

[Squirrell]

Whether or not there is a cell wall, the plasma membrane is responsible for the control of fluids entering or exiting the cell. However, a cell wall is very handy for water retention; in some cases it's necessary for survival.

[JackBean]

and which prokaryotic cells specifically do not have the cell wall?

[JorgeLobo]

Plasma membrane in most cases (Think protoplassts) would generally be of limited function for suvival under specified but some Mycoplasma (prokarotes with no cell wall) are quite resistant. I'd look back at the lectures and reading to undrrstand prof's perspective,