Biological Membranes Flashcards
What is the first law of thermodynamics?
Energy cannot be created or destroyed, only redistributed.
What is the second law of thermodynamics?
The entropy of any isolated system not in thermal equilibrium will always increase.
What small molecules can pass through the lipid membrane via simple diffusion?
Water, carbon dioxide, oxygen, small lipid molecules such as hormones, drugs and toxins.
What does facilitated diffusion allow for the transport of?
What does it use and what condition is required?
The transport of charged, hydrophilic or bulky molecules, such as glucose.
It uses specific transporters but it requires a concentration difference.
How many subunits are ion channels made of.
Eukaryotic channels are what?
What hydrophobic segments make up the voltage gate?
What segments form the transmembrane pore?
Four subunits,
Eukaryotic channels are voltage gated,
S1-S4 make up the voltage gate,
S5 and S6 make up the transmembrane pore.
What forces potassium ions through the channel?
What powers this movement?
Repulsion forces the potassium ions through the channel, this is powered by diffusion.
What causes channel specificity in the ion channels?
It is caused by ion size and coordination of the water shell. Ions must lose their water shell to pass through the channel but due to different geometry/charge some ions cannot therefore cannot pass through.
What is primary active transport?
Give two examples of primary active transport systems.
Any system that uses ATP to directly move substance across a membrane.
ABC transporter
P-type transporter.
How many domains is a typical ABC transporter made of?
Name the two types of ABC transporter domains.
ABC transporters are made up of four domains.
They have a hydrophobic α-helical domain type which contains the substrate specificity.
They have a ATP binding cassette (ABC) domain type. ATP binds near the ABC domain interface.
What is the size in angstroms of the polar head of lipid bilayers?
What is the Size in angstroms of the hydrophobic core of lipid bilayers?
Polar head is 8Å
Hydrophobic core is 30Å
What are the four domains of P-type ATPases
The M domain (membrane bound)
The P domain (phosphorylation domain)
The N domain (ATP nucleotide domain)
The A domain (Actuator domain)
