ATP synthase

Question 1

What were the three experiments to support the chemiosmosis theroy

Answer 1

1. isolating mitochindria + mild detergant -> ETC functions and ATP synthase doesnt -> ATP synthase requires outter membrane + not in ETC
2. liposome with ATPsynthase + bacteriorhodosin in membrane -> light shone to create pmf inside, ATP synthase functions -> pmf is required not ETC
3. 2-3dinitrophenol (DNP) - oxidative phosphrylative uncoupler - pumps H+ back to marix -> no ATP synthase. pmf required

Question 2

What is the protomotic force (pmf)

Answer 2

This is the force generated by the ETC pumping H+
electrochemical gradient

electrical - high H3O+ intermemebrane space, OH- matrix
Chemical/pH - more H+ in IMS less in matrix -> moves down gradient

Question 3

What are the two types of divisions which F1 FO ATPsynthase can be broken into

Answer 3

F1 unit: within matrix
FO unit: within membrane

strator: no rotation - alpha + beta + acessory structure
rotor: rotation - gamma stalk, c subunit

Question 4

How does the pmf drive ATP synthase

Answer 4

H+ moves down channels into c-subunit driving rotation of the gamma stalk
rotor movement causes gamma stalk interactions with the alpha beta subunits leading to conformational changes through states to catalyse ADP+P phosphorylation
H+ leaves after rotation into matrix

Question 5

What are the different states of the stator alpha beta sub untis

Answer 5

open, ATP leaves -> ADP + P binds
loose, holds ADP + P for catylisation
tight, catylises ADP and P

Question 6

What occurs in the sub units when the gamma stalk rotates

Answer 6

1 movement shift occurs in two stages:

1. ATP leaves new loose state
2. ADP + P binds to loose state, ATP catylisis in tight state

Question 7

What is the impact of uncouplers to the ETC

Answer 7

ETC uncouplers such as DNP leads to the movement of H+ back to matrix removing pmf
leads to large energy gain in matrix as not stored in ATP -> heat and organ damage
ETC still functions as coenzymes being oxidised and reused