Lecture 17/18 Transport Through Membranes Flashcards
What are the features of passive transport?
No energy needed.
Solute travels down concentration gradient
What are the features of active transport?
Coupled to ATP hydrolysis
Solute travels against concentration gradient.
______ perform primary active transport?
Pumps
______ Transverse the membrane without needing extra energy
Carriers
_____ are used in passive transport?
Channels
What are the 4 domains of P-type ATPases?
- Transmembrane domain
- A/Actuator domain
- N/Nucleotide binding domain
- P/phosphorylation domain
What are the two examples of P-type ATPases given?
SERCA + Na/K pump (3:2 ratio)
What are the two examples of ABC transporters given?
MDR protein + MsbA
What is the function of ABC transporters?
Transporting small molecules from one side of the membrane to the other, or from one side of the transporter to the other using ATP.
Na-Glucose cotransport is an example of what?
Secondary active transport.
How does secondary active transport work?
After primary active transport creates a charged gradient, other molecules can follow the charge into or out of a molecule.
Secondary transporters can be antiporters? T/F
False, they have to be symporters
What are the seven factors affecting diffusion rates?
Magnitude of concentration gradient Size of the molecule Surface area: volume ratio Temperature Density of solvent Solubility of solute (nonpolar = soluble) Distance to destination
What are the two important features to Ion channels/
Selectivity filter
Gate
What are the three ways to gate an ion channel?
Voltage
Ligand
Stress
What 5 ion channels must work together in order to contract muscles? What are the steps?
- Depolarization opens voltage-gated calcium channels
- Exocytosed acetylcholine opens ligand-gated Sodium Channels
- Local depolarization opens adjacent voltage-gated sodium channels
- as the depolarization spreads, voltage gated calcium channels open
- coupled calcium-release channels embedded in the SR open.
What are the two examples of facilitated diffusion channels given in the lecture?
Gap Junctions - allow cytoplasm sharing
Aquaporins - let water but not ions through
