U1 - Membrane Proteins Flashcards
What holds integral membrane proteins within the phospholipid bilayer?
Regions of Hydrophobic R groups allow strong hydrophobic interactions to hold it.
Integral membrane proteins interact extensively with the hydrophobic region of membrane phospholipids.
What are some types integral proteins?
Some integral proteins are transmembrane proteins meaning they expand the entirety of the phospholipid bilayer
What are peripheral membrane proteins?
Peripheral membrane proteins have hydrophilic R groups on their surface of membranes, mainly by ionic and hydrogen bond interactions.
What do peripheral proteins interact with?
Many interact with the surfaces of integral proteins
What is the phospholipid bilayer a barrier to?
The phospholipid bilayer is a barrier to ions and most uncharged polar molecules
What type of molecules can pass directly through the bilayer?
Small molecules such as oxygen and carbon dioxide pass through the bilayer by simple diffusion.
What is facilitated diffusion?
Is the passive transport of substances across the membrane through specific membrane proteins.
What allows different cells to perform different functions?
The cells have different channel and transporter proteins
What do animal and plant channel proteins have in common?
They are both highly selective
What are the features of a channel protein?
Channels are multi-subunit proteins with the subunits arranged to form water-filled pores that extend across the membrane.
Some channels are gated and change conformation to allow or prevent diffusion
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What controls ligand gated channels?
They are controlled by the binding of signal molecules
What controls voltage-gated channels?
These are controlled by changes in ion concentration
How do transporter proteins allow molecules across?
Transporter proteins bind to the specific substance to be transported and undergo a conformational change to transfer the solute across the membrane.
Transporter proteins alternate between two conformations so that the binding site for a solute is sequentially exposed on one side of the bilayer, then the other.
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