The ability to pass through a membrane?

Answer 1

permeability

Answer 2

permeability

Answer 3

There are many ways. Smaller/hydrophobic molecules can diffuse down their gradient. Or there are ion pumps and protein channels. Other methods exist, but it is not just "holes," Biology is more complex than that! Think about it, if it was holes, why does't everything that can fit just cross? How would the cell keep harmful things out and important things in?

Answer 4

cell membrane is composed of two layers of fatty acids. These fatty acids have two "domains" - hydrophobic and hydrophilic. The acids are orientated towards themselves by their hydrophobic parts, thus the membrane, at last, is represented by hydrophilic, hydrophobic and hydrophobic layer, respectively.

Now, if a molecule wants to pass through the cell membrane by itself, without transporter proteins located in the membrane, it has to be hydrophobic. It will be attracted by the middle, hydrophobic layer inside the membrane due to hydrophobic interactions. Once being inside the membrane, it also tends to get out from the membrane - either out from the cell or inside the cell.

Another way is given by transport proteins - protein complexes firmly anchored in the membrane, passing through it. These can either be channel-like (and selectively allow specific molecules to get through) or transporter-like (like rotating door). The transporter-like proteins either require energy (ATP molecule) in order to transport the molecules it can transport, or use gradient of some atoms which naturally tend to leave (or go inside) the cell. - for example a Na+/Glucose transporter - there is a lot of Na+ inside the cell, more than outside, thus Na+ tend to leave the cell. Using this power, the transporter enables one glucose molecule per Na+ atom (which goes outside) go inside.

Answer 5

It is called the permeability. Plasma memebrane is partially permeable.

Answer 6

to pass through a membrane is osmosis

Answer 7

Bacterial

Answer 8

Channels