1.3 Membrane Proteins Flashcards
Describe integral and peripheral proteins
Peripheral - appendages loosely bound to the surface of the membrane, can be found inside or outside of membrane
Integral - often transmembrane proteins, penetrate the hydrophobic core of the lipid bilayer
Describe how integral and peripheral proteins are bound to the plasma membrane
Integral - hydrophobic R-groups allow strong hydrophobic interactions that hold integral proteins within the bilayer
Peripheral - hydrophillic R-groups are bound to the surface of the membrane mainly by ionic and hydrogen interaction
Describe the role of aquaporin
Aquaporins are ungated channel proteins therefore allowing water to pass through channel without the addition of a ligand
Describe the role of ligand gated channels
A ligand binds to the channel protein, changing its conformation, allowing solutes to pass through
Describe the stages of sodium/potassium pump action
- Na+K+ pump binds to 3 sodium molecules and 1 phosphate molecule inside the cell
- Energy provided by ATP to change the shape of the channel. Sodium ions are driven through channel
- Sodium ions released to the outside of the membrane and 2 potassium ions bind
- Release of the phosphate makes channel revert to its original form, releasing potassium inside the membrane
Describe the importance of the sodium-potassium pump
The sodium gradient created on the outside of the cell membrane allows passive transport for the glucose symport (GLUT-4)
Identify how phospholipid heads and tails interact with water
Phospholipid head is hydrophilic, so its attracted to water on the inside and outside of the membrane
The tail is hydrophobic so it is repelled by water an is burrowed between the heads of the bilayer
Sodium-Potassium pump and glucose symport (GLUT-4) - which is active and which is passive?
Sodium-Potassium Pump - active Glucose Symport (GLUT-4) - passive
