Membrane proteins Flashcards
What is a fluid mosaic model
A model that describes the structure of the cell membrane.
What holds integral membrane proteins with the phospholipid bilayer
Regions of hydrophobic R groups allow strong hydrophobic interactions that hold integral membrane proteins in the phospholipid bilayer.
What are transmembrane proteins
The protein spans the entirety of the cell membrane.
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 ionic and hydrogen bonding interactions.
Do peripheral membrane proteins interact with integral membrane proteins
Many peripheral proteins interact with the layers of the surfaces of integral membrane proteins.
What is the phospholipid bilayer
The phospholipid bilayer is a barrier to ions and most uncharged polar molecules.
What can go through the phospholipid bilayer
Some small molecules such as water and oxygen and carbon dioxide can pass through the bilayer by simple diffusion.
What is facilitated diffusion
The passive transport of substances across the membrane through specific transmembrane proteins.
Why do different cell types have different channel and transporter proteins
To perform specialised functions, different cell types have different channel and transporter proteins.
Are channel proteins highly selective
Channel proteins in animal and plant cells are highly selective. This means they let very few types of molecules pass through.
How do channel proteins affect diffusion
Some channel proteins are gated and change conformation to allow or prevent diffusion.
How are ligand-gated channels controlled
Ligand channels are controlled by the binding of signal molecules.
How are voltage-gated channels controlled
Voltage-gated channels are controlled by changes in ion concentration.
How do transporter proteins transfer solute across membranes
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 to transfer substances across the membrane
Active transport uses pump proteins that transport substances across the membrane against their concentration gradient.
What is required for active transport
A source of metabolic energy.
Why do some active transport proteins hydrolyse ATP
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 ATP that is hydrolysed by enzymes called
ATP that is hydrolysed by enzymes is called ATPases.
What determines the transport of the solute when a solute is 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.
What do ion pumps use to establish and maintain ion gradients
Ion pumps such as the sodium-potassium pump, use energy from the hydrolysis of ATP to establish maintenance gradients.
Does the sodium-potassium pump go with or against the concentration gradient
The sodium-potassium pump transports ions against a steep concentration gradient using energy directly from ATP hydrolysis.
What does the sodium-potassium pump do
It actively transports sodium ions out of the cell and potassium into the cell.
How does the sodium-potassium pump work
The pump has a high affinity for sodium ions inside the cell. Binding occurs and the pump is phosphorylated by ATP. The conformation changes and the affinity for sodium ions decreases. This means the sodium ions are released outside the cell. Potassium ions bind outside the cell. Dephosphorylation occurs and the conformation of the protein changes. Potassium ions are taken into the cell and the affinity returns to the start.
Why do many organisms have a high proportion of the basal metabolic rate in many organisms
The sodium-potassium pump is found in most animal cells, accounting for a high proportion of the basal metabolic rate in many organisms.
What drives the transport of glucose in the small intestine
The sodium gradient created by the sodium-potassium pump drives the active transport of glucose.
What is the glucose transporter responsible for
The glucose transporter is responsible for this glucose symport transports sodium ions and glucose and the same time and in the same direction.
