Chapter 12 - Transport Across Cell Membranes
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Transport proteins
Allow many water soluble molecules to move across hydrophobic region of cells membranes
Protein free artificial lipid bilayer
Impermeable to most water soluble molecules except for water
Why are proteins negatively charged
Due to carboxyl group
Sodium concentration is higher where
Outside the cell than inside
Potassium concentration is higher where
Inside than outside
Sodium is balanced by what
Chlorine
Potassium is balanced how
Variety of negatively charged ions and molecules
Transporter aka
Carrier
Transporter
Membrane protein that undergoes series of conformational changes to transfer small hydrophilic solutes across the liquid bilayer
Channel
Hydrophilic pore across the lipid bilayer through which specific inorganic ions or polar organic molecules can diffuse
Channels discriminates by
Size and electrical charge
Transfers molecules at much greater rate than transporter
Channels
Ion channel can exist either in _____ or ________ conformation, but it transports only in the _______ conformation
Open , closed Open
Transporters carry out _______________ while channels carry out ___________
Passive and active transporters Passive transport
Passive transport allows solutes moves
Down their concentration gradient
Simple diffusion
Gases and hormones
Facilitated diffusion
Sugars and inorganic ions
Facilitated diffusion consist of
Transporters and channels
Active transport
Allows solutes to move up or against concentration gradients from regions of their lower to higher concentration gradient…requires energy
Osmosis
Movement of water
Osmosis moves
Down their concentration gradient
Isotonic solution
Has the same concentration of solutes as the cell
Hypotonic solution
Has much lower concentration of solutes than the cell
Hypertonic solution
Has much higher concentration of solutes than the cell