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Life Sciences => Cells, Microbes & Viruses => Topic started by: scientizscht on 22/11/2018 13:27:02

Title: What molecules can pass freely from cell membranes?
Post by: scientizscht on 22/11/2018 13:27:02
Hello!

What molecules can pass freely from cell membranes?

Is there a complete list?
Or list of characteristics?

Thanks!
Title: Re: What molecules can pass freely from cell membranes?
Post by: evan_au on 28/01/2019 09:57:51
Cell membranes block flow of many molecules, because the cell membrane often has a dual hydrophilic and a hydrophobic layer.

However, there are many "transport proteins" which cross the cell membrane and which permit (or actively encourage) molecules to cross the cell membrane.

Different types of cells express different transport proteins.

See: https://en.wikipedia.org/wiki/Membrane_transport_protein
See: https://en.wikipedia.org/wiki/Lipid_bilayer
Title: Re: What molecules can pass freely from cell membranes?
Post by: chiralSPO on 28/01/2019 15:59:21
There is certainly NOT a complete list of molecules that can pass through membranes freely (there are almost certainly  more than 1040 such molecules!!)

There are some rules of thumb. Lipisnki's rule of 5 is not exactly what you're looking for, but I think it is probably a good place to start https://en.wikipedia.org/wiki/Lipinski%27s_rule_of_five

It is also important to note that there are also compounds (DMSO comes to mind) that can make membranes more permeable--allowing though molecules that wouldn't normally cross easily, or increasing the crossover rate for molecules that already could cross.
Title: Re: What molecules can pass freely from cell membranes?
Post by: evan_au on 05/07/2019 05:04:09
There have been prototypes of insulin sensors which periodically apply an electrical pulse, which breaks down cell walls and allows measurement of insulin; conceivably, the same method should work for other biomarkers too.

Apparently, they made pulse gentler than a defibrillator... very important for the customer experience!
Title: What molecules can pass freely from cell membranes
Post by: Evageasse on 27/09/2019 07:55:45
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Title: Re: What molecules can pass freely from cell membranes?
Post by: Hayseed on 27/09/2019 08:41:22
I don't believe they do pass freely.  They need a certain gate. So, it's not the molecules, it's the gates.
Title: Re: What molecules can pass freely from cell membranes?
Post by: Colin2B on 27/09/2019 22:31:09
Quote from: Evageasse on 27/09/2019 07:55:45
I think, that you are not right. I am assured. I suggest it to discuss.
If you think that’s not right, then discuss it here. Make your opinions known to us all.