BIS 103: The Electron Transport Chain

Question 1

What is complex 1 made of?

Answer 1

alpha helices, MANY

Question 2

Complex 1 e- route

Answer 2

1) 2-> NADH
2) 2-> FMN bound to protein
3) line of Fe-S centers, varied
4) ubiqinone OR to pump protons

Question 3

Complex 1 stuctural anomaly

Answer 3

long horizontal a helix - arm for proton transfer

conformation change - opens channel for H entry then exit for 3 of 4 H+’s

Question 4

What side is most of Complex 1 facing?

Answer 4

N side

Question 5

Where does 4th proton of complex 1 pass?

Answer 5

between membrane arm and rest

Question 6

Arm rxn of complex 1

Answer 6

e- binds
pushes arm to open hole
release t close hole, open on P side

Question 7

What does the heme on Complex 2 do?

Answer 7

doesnt accept e-

binds oxygen-stops oxygen from grabbing e- in passage and making a free radical

Question 8

Complex 2 reactions

Answer 8

1. succinate binds at active site at N SIDE, gives e-
2. moves thru Fe-S complexes
3. Passes e- to Q in membrane to make QH2

Question 9

How is Q made in times of emergency?

Answer 9

1. fatty acyl - Coa’s send e- to FAD, which make Q in seprate enzyme (not complex 1-4)
2. NADH (indirectly) : e- given to Q

Question 10

Were does 2Fe-2S complex in Complex 3 move between?

Answer 10

Qp to Heme c1

Question 11

hammerheads of Complex 3 - rxn, why?

Answer 11

alternate e- grabbing and sending e- to cytC

1 at time because cytC holds 1 at a time

Question 12

In what complex are Rieske iron-sulfur proteins?

Answer 12

Complex 3 hammerheads

Question 13

Which complex has a possibly allosteric (unverified fxn) subunit?

Answer 13

complex 3

Question 14

What are in the 2 chambers of complex 3?

Answer 14

a population of coQ’s

Question 15

Methods of H pumping in the complexes

Answer 15

1 - idk - arm?
2- none
3- Q cycle
4 - D and K paths - hopping

Question 16

Mechanism of Complex 3

Answer 16

1. QH2 dumps :
   
   • 1e- to Rieske -> heme c1-> cytC
   • 1e- to Q -> Q*- radical, neg charge or another to Q
   • 2 H” to pass into P side

Question 17

ratios from NADH

Answer 17

1 NADH to 1 Q to 4H (need 2 rounds in Comp 3)

Question 18

progression of e- in complex 4

Answer 18

cytC (4 total)
1st binuclear site (2Cu) subunit 2
2nd binuclear site (Cu Fe) subunit 1
oxygen

Question 19

complex 4 takes in how many H+? via what?

Answer 19

8 H+ :

D path takes 6 (into P side), K path takes 2 (to water), so K needs extra

Question 20

complex 4 gatekeeper = ?

Answer 20

polypeptide loop ending with 1 glu

chooses if h+ crosses or forms water

Question 21

gatekeeper a acid chemistry

Answer 21

glutamine has VERY different pka: 9.7

-grabs H+ to suck through - to filled with water and weak ab groups

Question 22

What drives protons to the N side?

Answer 22

entropy

electrochemical force

Question 23

subunits of ATP synthase, structure and functions

Answer 23

F1 - 3 dimers of alpha/beta subunits (fit atp btwn to make)

F0 - 7 parts, turn rotor (gamma) to free ATP

Question 24

ATP synthase subunit with half channels

Answer 24

a

Question 25

ATP synthase subunit made of ___# of c subunits

Answer 25

baseplate - # varies by organism

Question 26

ATP synthase c subunit structure , connections

Answer 26

2 alpha helices | connected to plexible polypep chain and gamma subunits

Question 27

draw ATP synthase (list units) - function

Answer 27

a baseplate 2 b2's c's ``` alpha beta gamma delta epsilon ```

Question 28

ATP Synthase' H+ are driven by

Answer 28

entropy | - charge on asp

Question 29

how is there a positive arginine in organic NONPOLAR subunit?

Answer 29

-there are negatively charge Aspartate's whirling around if arent bound to H+ - spin fast - net

Question 30

Where is arg on ATP Synthase? function?

Answer 30

on subunit a | protons displace it, stopping protons from entering N half channel without going around

Question 31

Where is asp on ATP Synthase?

Answer 31

alpha helix of c subunit

Question 32

chemistry of asp- of ATP Synthase

Answer 32

high pka in organic solvent - binds H | low pka near aqueous - releases H

Question 33

What makes H leave into the _ half channel?

Answer 33

N - it is coated with nonpolar weak ab groups and filled with water

Question 34

ATP Synthase experiment - parts

Answer 34

- histine on a/b subunits to attach to Nickel complex - bind biotin to avidin to actin filament - actin filament to fluorescent parkers make move by adding ATP

Question 35

mechanism of ATP synthesis in ATP Synthase

Answer 35

1) adp/pi binds to mid of alpha-beta subunit 2) it's formed 3) gamma subunit (asymmetric) kicks off the ATP

Question 36

most of the E put into ATP is used to

Answer 36

kick ATP out - NOT to make it

Question 37

H+ to make ATP - where?

Answer 37

3 H+ for each 120 turn 1 to pump Pi in 4 total

Question 38

what pumps Pi in ____?

Answer 38

symporter | into the matrix

Question 39

What pumps ATP4- and ADP3-? where does each go?

Answer 39

ATP4- into intermembrane space | ADP into matrix

Question 40

What brings in P?

Answer 40

symporter, with H+