Lecture and Reading 17; Membranes and Proteins

Question 1

Q # 30 What are the two components of the electrochemical gradient?

Answer 1

The two components of the electrochemical gradient are: 1) the difference in solute concentration and 2) and the electrical gradient across a membrane.

Question 2

Q # 31 In what ways are membrane transporters and enzymes similar? In what ways are they different?

Answer 2

The intermediate stage of transmembrane passage and the transition state of an enzyme are very similar. An activation energy barrier must be overcome. Membrane proteins lower Ea of membrane passage; membrane transporters are different, because they do not chemically alter their substrates.

Question 3

Passive transporters

Answer 3

Simply facilitate diffusion down a concentration gradient

Question 4

Active transporters

Answer 4

Drives substrates across the membrane against a concentration gradient, some using energy provided directly a chemical reaction and come coupling uphill reactions with downhill transport (secondary active transport)

Question 5

Q # 39 What information does ∆psy encode concerning the interior and exterior of a cell?

Answer 5

∆psy is the transmembrane potential in V.

Question 6

Primary active transport

Answer 6

Solute accumulation is coupled directly to an exergonic chemical reaction, such as conversion of ATP to ADP + Pi.

Question 7

Secondary active transport

Answer 7

Occurs when endergonic (uphill) transport of one solute is coupled to the exergonic (downhill) flow of a different solute that was originally pumped uphill by primary active transport

Question 8

∆G transport

Answer 8

∆Gt = RT x ln (C1/C2)

Question 9

∆G transport electrogenic

Answer 9

∆G = RT x ln (C2/C1) + Zf∆psy; where Z is the charge of the ion, F is the faraday constant; and ∆psy is the transmembrane potential in V.