The number of molecules (solute) per unit of solvent. (the solvent in cells is water)
Is reached when the rate of movement in one direction is the same as the rate of movement in the other direction.
The cells expends energy to maintain a steady inside environment state.
Impose a barrier between the inside and the outside of the cell. Hydrophillic "heads" and hydrophobic "tails". The cell membrane.
Molecules that dissolve in water. (polar)
Will not dissolve in water. (non-polar)
Receptor and recognition proteins. They have an oligosaccharide molecule attached to them.
Aka "channel proteins". These fold in such a way as to create a hole (membrane pores) down their center. Allow water soluble substances to cross the lipid bilayer.
Bind extracellular substances which then cause changes in the cell. (exp. neurotransmitter receptors)
Also gycopoteins. Function as ID tags. Identify cell type within an organism. Used to identify one organism from another.
Some may be glycoproteins. Locate and stick to others of the same type in multicellular organisms.
When two locations differ in the amount of something, then there is a _____ between them.
Cell expends no energy; passive transport; The process in which there is movement of a substance from an area of high concentration of that substance to an area of lower concentration
Like doors; can be shut. Substances can only be moved through them by the expenditure of energy in the form of ATP.
Like open windows. (aka "pores") Can move in both directions. Net movement depends only on the concentration gradient.
Solutes are "helped" to move down their concentration gradients by the presence of channels.
Active Transport Proteins
In cells: water; The substance in which a solute is dissolved.
The dissolved substance in a solution.
the diffusion of water across a semi-permeable membrane
A solution that is more concentrated than another. (Little water)
A solution is less concentrated. (Lots of water)
The solutions are equal in concentration