What would happen if the cell membrane were fully permeable to all substances in the cell's environment?

Expert Answers

An illustration of the letter 'A' in a speech bubbles

The cell membrane is selectively permeable, that is, it allows the entry to only a few molecules, while barring all the others. If the cell membrane was completely permeable, all the molecules will gain access to the cell interior. These molecules may include toxins and will be able to harm the cell or kill it. Thus, the semi-permeable or selectively permeable nature of cell membrane is necessary for cell survival and routine operation.

The transport of molecules across the membrane is necessary, since the cell cannot produce all the molecules it needs for routine operation and also to dispose off (or excrete) the molecules that are not useful to the cell. Thus, selectivity in terms of transport of molecules (between the cell interior and exterior environment) is necessary.

Hope this helps. 

Approved by eNotes Editorial
An illustration of the letter 'A' in a speech bubbles

What would happen if the cell membrane were fully permeable to all substances in the cell’s environment?

Interesting question. If the membrane were fully permeable to all substances, then anything could enter the cell. This would upset the balance between the cell's contents and the outside environment. There is only so much ability to store substances and utilize substances, therefore, the cell would not be able to maintain homeostasis. For example, the cell membrane is selectively permeable and allows substances to cross the membrane if there is a concentration gradient, and if those substances are small enough to cross the membrane. Sometimes, the proteins in the cell membrane help materials enter the cell. However, this is all regulated at a particular rate. If the membrane was fully permeable, substances would enter constantly and the cell couldn't use or handle everything coming in, resulting in the death of the cell.

See eNotes Ad-Free

Start your 48-hour free trial to get access to more than 30,000 additional guides and more than 350,000 Homework Help questions answered by our experts.

Get 48 Hours Free Access
Last Updated on