membrane proteins Flashcards
what do regions of hydrophobic r groups allow
Regions of hydrophobic R groups allow strong hydrophobic interactions that hold integral membrane proteins within the phospholipid bilayer
what do Peripheral membrane proteins have
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
why do Transporter proteins bind to the specific substance?
Transporter proteins bind to the specific substance to be transported and undergo a conformational change to transfer the solute across the membrane
what does active transport use
Active transport uses pump proteins that transfer substances across the membrane against their concentration gradient
what is required for active transport
A source of metabolic energy is required for active transport
what do some active transport proteins hydrolyze
Some active transport proteins hydrolyze ATP directly to provide the energy for the conformational change required to move substances across the membrane
are some integral proteins are transmembrane proteins
Yes. some integral proteins are transmembrane proteins
what do many peripheral membrane proteins interact with
Many peripheral membrane proteins interact with the surfaces of integral membrane proteins
what do integral membrane proteins interact extensively with
Integral membrane proteins interact
extensively with the hydrophobic region of membrane phospholipids.
what is the phospholipid bilayer
The phospholipid bilayer is a barrier to ions and most uncharged polar molecules
how do small molecules pass through the bilayer
Some small molecules, such as oxygen and carbon dioxide, 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
what do different cells have that allow them to perform specialised functions
To perform specialised functions, different cell types have different channel and transporter proteins
are most channel proteins in animal and plant cells highly selective?
Yes. Most channel proteins in animal and plant cells are 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 gated channel proteins do
Some channel proteins are gated and
change conformation to allow or prevent diffusion
what are ligand-gated channels controlled by and what are voltage-gated channels controlled by
Ligand-gated channels are controlled by the binding of signal molecules, and voltage gated channels are controlled by changes in ion concentration
what are pumps that mediate active transport?
Pumps that mediate active transport are transporter proteins coupled to an energy source
what do transporters alternate between
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 determines the transport of a solute carrying a net charge
For a solute carrying a net charge, the
concentration gradient and the electrical potential difference combine to form the electrochemical gradient that determines the
transport of the solute
when is a membrane potential created
A membrane potential (an electrical potential difference) is created when there is a difference in electrical charge on the two sides of the membrane.
Ion pumps, such as the sodium-potassium pump, use energy from what ?
Ion pumps, such as the sodium-potassium pump, use energy from the hydrolysis of ATP to establish and maintain ion gradients
what does the sodium-potassium pump do
The sodium-potassium pump transports ions against a steep concentration gradient using energy directly from ATP hydrolysis.
It actively transports sodium ions out of the cell and potassium ions into the cell
how does the sodium-potassium pump work as a whole
The pump has high affinity for sodium ions inside the cell; binding occurs; phosphorylation by ATP; conformation changes; affinity for sodium ions decreases; sodium ions released outside of the cell; potassium ions bind outside the cell; dephosphorylation; conformation changes; potassium ions taken into cell; affinity returns
to start
For each ATP hydrolysed, three sodium ions are transported out of the …
For each ATP hydrolysed, three sodium ions are transported out of the cell and two potassium ions are transported into the cell. This establishes both concentration gradients and an electrical gradient
what type of cells is the sodium-potassium pump most found in
The sodium-potassium pump is found in most animal cells, accounting for a high proportion
of the basal metabolic rate in many
organisms
what does the sodium-potassium pump do in the small intestine?
In the small intestine, the sodium gradient created by the sodium-potassium pump drives the active transport of glucose
what does the sodium-potassium pump do in the intestinal epithelial cells
In intestinal epithelial cells the sodiumpotassium pump generates a sodium ion gradient across the plasma membrane.
what is the glucose transporter responsible for
The glucose transporter responsible for this glucose symport transports sodium ions and glucose at the same time and in the same direction
how do sodium ions enter the cell
Sodium ions enter the cell down their
concentration gradient; the simultaneous transport of glucose pumps glucose into the
cell against its concentration gradient.
