1.3.1 membrane proteins; movement of molecules across membranes Flashcards
what do regions of hydrophobic R groups allow
they allow 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 are some integral membrane proteins known as
transmembrane proteins
what type of R groups do peripheral membrane proteins have
hydrophilic
where are peripheral membrane proteins bound
the surface of membranes
what are the main bonds that allow peripheral membrane proteins to bind with the membrane
ionic and hydrogen bonds
what do many of the peripheral membrane proteins interact with
the surfaces of integral membrane proteins
what is the phospholipid bilayer
a barrier to ions and most uncharged polar molecules
what are examples of small molecules that can pass through the bilayer by simple diffusion
oxygen and carbon dioxide
what is facilitated diffusion
the passive transport of substances across the membrane through specific transmembrane proteins
what features do different cell types have that allow them to perform specialised functions
different channels and transporter proteins
are most channel proteins in animal and plant cells highly selective
yes
what are channels
mutli subunit proteins with the subunits arranged to form water filled pores that extend across the membrane
how do gated channel proteins allow or prevent diffusion
by changing their conformation
what are ligand-gated channels controlled by
the binding of signal molecules
what are voltage gated channels controlled by
changes in ion concentration
where do transporter proteins bind to
the specific substance to be transported and undergo a conformational change to transfer the solute across the membrane
what do transporter proteins do
they alternate between two conformations so that the binding site for a solute is sequentially exposed on one side of the bilayer, and then the other
what proteins does active transport use
pump proteins that transfer substances across the membrane against their concentration gradient
what are pumps that mediate active transport
transporter proteins coupled to an energy source
what is required for active transport
a source of metabolic energy
what does ATPase do
hydrolyse ATP
why do some active transport proteins hydrolyse ATP directly
to provide the energy for the conformational change required to move substances across the membrane
