Unit 1 - Membrane Proteins Flashcards
(35 cards)
How are integral membrane proteins held within the phospholipid bilayer?
hydrophobic R groups allow strong hydrophobic interactions that hold integral membrane proteins within the
phospholipid bilayer
What do integral proteins react extensively with?
the hydrophobic region of membrane phospholipids.
What are some integral membrane proteins?
Some integral membrane proteins are
transmembrane proteins
How are peripheral membrane proteins bound the membrane of the phospholipid bilayer?
Peripheral membrane proteins have
hydrophilic R groups on their surface and are
bound to the surface of membranes, mainly
by ionic and hydrogen bond interactions
What is the function of the phospholipid bilayer?
The phospholipid bilayer is a barrier to ions
and most uncharged polar molecules
What small molecules can pass through the phospholipid bilayer by simple diffusion?
Some small molecules, such as oxygen and
carbon dioxide,
How do small molecules pass through the bilayer?
pass through the bilayer by simple diffusion
What is facilitated diffusion?
Facilitated diffusion is the passive transport
of substances across the membrane through
specific transmembrane proteins
To perform specialised functions what do different cell types have?
have different channel and
transporter proteins
What is a feature of most channel proteins in animal and plant cells?
highly selective
What are channels?
Channels are multi-subunit proteins with the
subunits arranged to form water-filled pores
that extend across the membrane
What do channel proteins do/have?
Some channel proteins are gated and
change conformation to allow or prevent
diffusion
What are ligand gated channels?
Ligand-gated channels are controlled by the
binding of signal molecules
What are voltage-gated channels?
Voltage-gated channels are controlled by changes in
ion concentration
What do transporter proteins do?
Transporter proteins bind to the specific
substance to be transported and undergo a conformational change to transfer the solute across the membrane
Why do transporters alternate?
Transporters alternate between two
conformations so that the binding site for a
solute is sequentially exposed on one side of
the bilayer, then the other.
What is active transport?
Active transport uses pump proteins that
transfer substances across the membrane
against their concentration gradient
What are the pumps involved in active transport connected to?
coupled to an energy source.
What is required for active transport to occur?
A source of metabolic energy is required for
active transport
What hydrolyses ATP?
ATPases
What do ATPases do?
Hydrolyse ATP
Why doe some active transport proteins hydrolyse ATP directly?
to provide the energy for the
conformational change required to move
substances across the membrane
What is the electrochemical gradient?
the concentration gradient and the electrical potential difference combine to form the electrochemical gradient
When is the electrochemical gradient required and what does it determine?
It is required for a solute carrying a net charge and determines the transport of the solute.