1.3 a) Movement of Molecules Across Membranes Flashcards
The ___ ___ model describes the structure of the plasma membrane.
fluid mosaic
The cell membrane is comprised of a bilayer of ___ molecules and a patchwork of ___ molecules.
phospholipid, protein
Phospholipid molecules have ___ heads and ___ tails.
hydrophilic, hydrophobic
What gives the membrane its fluid quality?
the constantly moving phospholipids
Membrane proteins can be classified as ___ or ___.
integral or peripheral
Integral membrane proteins react extensively with the ___ region of the phospholipids in the ___ ___.
Which region of phospholipids is hydrophobic?
hydrophobic, plasma membrane.
The tail, you cutesie
Regions of ___ R groups allow strong interactions that hold ___ membrane proteins within the phospholipid bilayer.
hydrophobic, integral
Some integral membrane proteins are ___ proteins.
transmembrane
Peripheral membrane proteins have ___ R groups on their surface that make ___ and ___ bond interactions (primarily) with the surface of the membrane - aka the (head/tail) of the phospholipid molecules.
hydrophilic, ionic, hydrogen, heads
To reiterate; peripheral membrane proteins ___ to the membrane through ___ and ___ bond interactions.
bind, ionic, hydrogen
Many peripheral membrane proteins interact with the surface of ___ ___ ___.
integral membrane proteins
What is the phospholipid bilayer a barrier to?
ions and most uncharged particles
Name 2 small molecules that are able to pass through the membrane by simple diffusion.
oxygen and carbon dioxide
What is diffusion?
The movement of molecules across a membrane, down their concentration gradient
Facilitated diffusion is the ___ transport of substances across the membrane through specific ___ proteins.
passive, channel
Different cell types have different ___ and ___ proteins, allowing them to perform their specialised functions.
channel, transporter
Channel proteins are highly ___.
selective
Channels are multi-___ proteins, with the ___ arranged to form a ___ that extends through the membrane.
subunit, subunits, pore
Since water diffuses very slowly across the membrane, most water travels through the membrane protein ___.
aquaporin
Some channel proteins are gated, and can change their ___ to allow or ___ diffusion.
conformation, prevent
Name the two types of gated channels.
Ligand gated and voltage gated.
Ligand gated channels are controlled by…
the binding of signal molecules
Voltage gated channels are controlled by ___ in the ___ of different ___.
changes, concentration, ions
Transporter proteins undergo ___ changes to transport ___ across the ___.
conformational, substances/molecules/solutes, membrane
Transporter proteins alternate between two conformations, so that the ___ site is sequentially ___ on one side of the bilayer, and then the other.
binding, exposed
Active transport uses ___ proteins that transfer substances across the membrane against the ___ ____.
pump, concentration gradient
Pump proteins are ___ proteins with an ___ ___ attached.
transporter, energy source
The conformational change of the ___ protein in active transport requires energy which comes from the ___ of ___.
pump, hydrolysis of ATP
ATP is hydrolysed into… by enzymes called…
ATP + Pi, ATPases
Some pump proteins that carry out active transport can ___ the ATP directly, without the need for ____ enzymes.
hydrolyse, ATPase
The ATP required for active transport provides energy for…
the conformational change of the pump
(although in passive transport, pumps still change their conformation, but since the molecules are being transported down their concentration gradient, ATP is not required for this)
One example of a pump protein that does not utilise ATPases is…
the Sodium-Potassium Pump (Na-K pump)
(Hydrophobic/Hydrophilic) signalling molecules can diffuse through the membrane.
hydrophobic (think O2 and CO2 can diffuse directly- and are hydrophobic, and steroid hormones also can (oestrogen and testosterone))
