Question

Short / Long answer type questions.
How do neutral solutes move across the plasm membrane ? Can the polar molecules also move across it in the same way ? If not, then how are these transported across the membrane ?

Answer 1

• The plasma membrane is a semi permeable membrane.
• There are 3 ways by which a molecule can enter through the plasma membrane
• The first one being the passive diffusion where the molecules that are very small and lipid soluble will simply diffuse through the plasma membrane as per their concentration gradient. The molecules will travel from the area of their higher concentration to the area of their lower concentration.
• The second way is through the faciliated diffuse where protein transporters in the plasma membrane are used for the transport of the molecules, the molecules attach with the protein and pass through it and are released inside or outside the plasma membrane where ever their destination is. No energy is used for this kind of transport for the molecules that are not soluble in lipids. The molecules are able to be transported dowmhill their concentration gradient.
• The third way is by activated diffusion this is were the molecules are transported uphill their concentration gradient by the use of energy (ATP) through the transport proteins .
• Polar molecules are those that are soluble in water. This molecules are transported across the plasma membrane either by facilated or activated diffusion and if they are very small or lipid soluble then they are simply diffused by passive diffusion.