biology notes - -Isotonic solution: solute concentration...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
Selective permeability - Membrane structure resilts in selective permeability - A cell must exchange materials with its surrounding cells. - Transport proteins allow passage of hydrophilic substances across the membrane. - Some transport proteins called channel proteins have a hydrophilic channel that certain molecules or ions can use as a tunnel. - Net diffusion equilibrium - Substances diffuse down their concentration (energy) gradient - Osmosis is another type of passive transport. - It is the diffusion of water across a selectively permeable membrane. - Tonicity is the ablity of a solution to cause a cell to gain or lose water
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: -Isotonic solution: solute concentration -Cell walls help maintain water balance-A plant cell in a hypotonic solution swells until the wall opposes uptake; the cell is now turgid(firm)-In facilitated diffusion, transport proteins speed movement of molecules across the plasma membrane-Active transport moves solutes against their concentration gradients using special carrier proteins and energy.-Most useful type of energy in cells: ATP.-The sodium-potassium pump is one type of active transport.-...
View Full Document

Ask a homework question - tutors are online