1o- Movement of molecules across membranes Flashcards
What do regions of hydrophobic R groups allow for?
Strong hydrophobic interactions that hold integral membrane proteins within the phospholipid bilayer
What do integral membrane proteins interact extensively with?
The hydrophobic region of membrane phospholipids
What can some integral membrane proteins be?
Transmembrane proteins
What can be said about peripheral membrane proteins?
They have hydrophilic R groups on their surface, and are bound to the surface of membranes, mainly by ionic and hydrogen bond interactions
What do many peripheral membrane proteins do?
Interact with the surface of integral membrane proteins
What is the phospholipid bilayer a barrier to?
Ions and most uncharged polar molecules
What can pass through the phospholipid bilayer by simple diffusion?
Some small molecules, such as oxygen and carbon dioxide
What is facilitated diffusion?
The passive transport of substances across the membrane through specific transmembrane proteins
What do different cell types have in order to perform specialised functions?
Different channel and transporter proteins
In animal and plant cells what are most channel proteins?
Highly selective
What are channels?
Multi-subunit proteins with the subunits arranged to form water-filled pores that extend across the membrane
Some channel proteins are said to be gated, what does this mean?
They change conformation to allow or prevent diffusion
What are ligand-gated channels controlled by?
The binding of signal molecules
What are voltage-gated channels controlled by?
Changes in ion concentration
How do transporter proteins work?
They bind to the specific substance to be transported and undergo a conformational change to transfer the solute across the membrane
