FINAL EXAM CHAPTER 20 Electron transport chain

Question 1

what do electrons flow to?

Answer 1

molecules with higher standard reduction potential

Question 2

How do you tell if the direction of flow is left or right by just looking at the EMF/standard reduction potential?

Answer 2

If the value is positive that means it flows right but negative means the opposite way being left.

Question 3

For any pair of ____ reactions the ____ can be calculated from the difference in EMF.

Answer 3

1/2, Delta G

Question 4

define oxidizing agent

Answer 4

a substance that causes oxidation by accepting electrons

Question 5

define reducing agent

Answer 5

a substance that causes reduction by losing electrons

Question 6

In eukaryotes where does the electron transport chain and ATP synthesis occur?

Answer 6

MItochondria

Question 7

Where does the citric acid cycle take place for eukaryotes?

Answer 7

Mitochondrial matrix

Question 8

What are the names of the four electron carriers of the complexes?

Answer 8

1. Flavin mononucleotide(FMN)
2. Iron associated with sulfur in proteins (iron-sulfur proteins)
3. Iron incorporated into hemes that are embedded in proteins called cytochromes
4. A mobile electron carrier called coenzyme Q

Question 9

When FMN is reduced to FMNH2 how many electrons and protons are added in the reaction?

Answer 9

2e- and 2H+

Question 10

What is Coenzyme Q also known as and what are the characteristics of Coenzyme Q ?

Answer 10

Ubiquinone and it is a lipid soluble and can diffuse through membrane accepting and donating electron.

Question 11

How do Hemes accept or donate electrons?

Answer 11

A family of cytochromes that uses heme irons to accept and donate electrons

Question 12

how do Iron-Sulphur proteins accept or donate electrons ?

Answer 12

They use inorganic Sulphur and organ sulphur from Cys residues to build a redox Centre where iron atoms can donate and accept electrons

Question 13

What happens throughout the complexes of the electron transport chain and what carries the electrons between complexes

Answer 13

Ubiquinone(Q) accepts the electrons from both Complex 1 and complex 2 and delivers them to complex 3, then complex 3 pumps protons through the membrane and passes it on to cytochrome C for transport to the complex 4

Question 14

Explain the q cycle step 1

Answer 14

The ubiquinol binds to complex 3 and two protons are pumped into the membrane and then ubiquinol releases its electrons and one goes into the Cytochrome C and the other into Cytochrome B. SO since there is only space for one electron in allowed to the cytochrome C pathway the other electron has to go the other way and bind to ubiquinone causing it to Semiquinone Intermediate .

Question 15

Explain q cycle step 2

Answer 15

Once the binding of ubiquinone takes place again the pathways repeat and when one of the electrons go through Cytochrome b it pulls 2H+ from the matrix as well to make QH2 (Ubiquinol) and once this is made it get put back in the Q pool and is reused to repeat these steps

Question 16

What contributes to the proton gradient?

Answer 16

Pumped and chemical protons