This takes place when molecules diffuse across the cell membrane by travelling through specific transport proteins. It occurs down a concentration gradient - molecules move from an area of high to ...

They are semi-permeable, which means that some molecules can diffuse across ... and sometimes move materials against them is vital to cell health and maintenance. Thanks to membrane barriers ...

Eventually, the concentration either side of the membrane will be the ... there is therefore no net movement in one direction. Water leaves the cell by osmosis. The cytoplasm shrinks and pulls ...

Most cell signals are ... molecules that travel across the tiny spaces between adjacent neurons or between neurons and muscle cells. Other signaling molecules must move much farther to reach ...

When they examined which proteins were located in the ER's membrane tubules ... a network of fibers that helps cells hold their shape, move, and connect with surfaces through sticky junctions ...