How does a molecules polarity affect the way it passes through a membrane?

Answer 1

Yes, the more polar a molecule is, the less permeable the molecule becomes. This is because of the phospholipid bilayer seperating the extra and intracellular environments. Non polar molecules (fats) and small molecules can pass quickly through the membrane.

Answer 2

The permeability of membranes is the ease of molecules to pass through it. Permability depends mainly on the electric charge of the molecule and to a lesser extent the molar mass of the molecule. Electrically-neutral and small molecules pass the membrane easier than charged, large ones.

Answer 3

Temperature can cause particles to move quickly which means there are more successful collisions between particles in a reaction. However it is different to when you increase the temperature in a cell. Phospholipids and proteins within a cell membrane are constantly moving. However if you increase the temperature. As the temperature increases in the cell the phospholipid molecules get hotter and start to vibrate more. They move significantly more than at their normal state leaving gaps in the membrane which wouldn't usually be there. Protein molecules also do this. They vibrate so much that they lose their shape and come apart leaving a large gap in the membrane. If you were to decrease the temperature however it will decrease the permeability of the membrane. The phospholipids vibrate less and stick together tightly causing rare openings between where molecules may pass. Low temperatures make it difficult for protein transporters to work as it is hard to provide ATP needed for active transport. Furthermore low temperatures mean molecules and ions have less successful collisions when hitting the membrane and passing through it.

For example, if you were to take a piece of beetroot and place it in water, it will remain colourless as there are no gaps between the phospholipids and protein. However if you were to increase the temperature of the beetroot then the water will go red because of the loss of red pigment in the cell. When the cell is heated up the phospholipids and proteins in the cell vibrate more so making temporary holes in the between them. As water is passed in by osmosis the red pigment is brought out into the water.

This increases the rate of diffusion by the speed of which molecules move across the membrane. Because the temperature has been increased there are more gaps so the molecules which are being diffused move quicker as there is an increase in kinetic energy. The molecules are moving faster so will get diffused faster because the membrane is more permeable.

Answer 4

yes.....

Answer 5

YES