Membrane Proteins

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