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What term is used to describe the structure of the plasma membrane
fluid mosaic model
Where are integral proteins found
within the membrane
What do intergal proteins interact with?
the hydrophobic region of membrane phospholipids
Regions of hydrophobic R groups allow…
strong hydrophobic interactions that hold integral membrane proteins within the phopholipid bilayer
Some integral membrane proteins are…
transmembrane proteins
Where are peripheral proteins found
on the surface of the membrane
What do peripheral membrane proteins interact with?
the surfaces of integral membrane proteins
What do peripheral membranes have on the surface and what are they bound to?
hydrophillic R groups - bound to the surface of membranes, mainly by ionic and hydrogen bond interactions
What is the phospholipid bilayer a barrier against?
ions and most uncharged polar molecules
What molecules can pass through the phospholipid bilayer and how?
carbon dioxide and oxygen through simple diffusion
What is facilitated diffusion?
the passive transport of substances across the membrane through specific transmembrane proteins
What are ligand-gated channels controlled by?
the binding of signal molecules
What are voltage-gated channels controlled by
changes in ion concentration
What are channels?
multi-subunit proteins with the subunits arranged to form water-filled pores that extend across the membrane
What does active transport consist of?
the use of pump proteins that transfer substances across the membrane against their concentration gradient
What is required for active transport?
metabolic energy source
What do ATPases do?
hydrolyse ATP
What is membrane potential and when is it created?
an electrical potential difference - created by a difference in electrical charge on each side of the membrane
Is the sodium potassium pump a form of active of passive transport?
active
In the sodium potassium pump, for each ATP hydrolysed, how many Na and K ions are transported and where to?
3 sodium ions out of the cell
2 potassium ions into the cell
What cells is the sodium potassium pump found most in and why?
animal cells to account for a high proportion of the basal metabolic rate in many organisms
What bind to transporter proteins and why?
specific substances to be transported across the membrane; they undergo a conformational change
Transporter proteins alternate between how many conformations and why?
two confirmations so that the binding site for a solute is sequentially exposed on each side of the bilayer
In the small intestine, the sodium gradient created by the sodium potassium pump drives what?
the active transport of glucose
What is the name of the glucose transporter?
glucose symport
What does glucose symport do?
transports sodium ions and glucose at the same time and in the same direction