Lecture 10-Mitochondria And Respiration

Question 1

Chemiosmotic hypothesis

Answer 1

G

Question 2

Oxidative phosphorylation

Answer 2

F

Question 3

e transport chain

Answer 3

C

Question 4

Nucleotide-linked nicotinamide cofactors

Answer 4

• These are cofactor electron acceptors
• These are electron carriers that are considered to be “true carriers” because they are loosely bound, freely dissociable
• NAD and NADP are examples

Question 5

FAD/FMN cofactors

Answer 5

• Flavoproteins
• They are isoalloxazine acceptors and are tightly bound to the enzymes, making them prosthetic groups
• They transfer electrons via radical chemistry, by transferring a radical in the form of an electron and a proton?
• They can do single electron transfers as well as two electron transfers

Question 6

Semiquinone

Answer 6

G

Question 7

Ubiquinone

Answer 7

• An example of an inner membrane electron carrier molecule
• is freely diffusible in the inner membrane
• a membrane-bound carrier
• Also picks up electrons in the form of radicals
• Has a lipid tail that keeps in anchored to the mitochondrial inner membrane

Question 8

Cytochromes

Answer 8

• An example of an inner membrane electron carrier molecule
• Is heme-like, with an iron in the center of a ring very much like in heme
• Most cytochromes are integral membrane-proteins?
• Pick up electrons and drop off electrons by oxidizing and reducing the iron to Fe2+ and Fe3+

Question 9

Heme

Answer 9

• In hemoglobin

Question 10

Iron-sulfate proteins

Answer 10

• Example of an inner membrane electron carrier molecule
• Also hold iron
• Sulfur forms a “cage” to hold the iron

Question 11

Complexes I-IV

Answer 11

G

Question 12

NADH Dehydrogenase

Answer 12

• Complex I in the e- transport chain/respiratory cycle
• Is in the inner mitochondrial membrane
• Takes electrons from NADH and eventually added to coenzyme q to make the quinol
• Has FMN and Fe-S as prosthetic groups
• Individual protons are also moved across the membrane through this complex, against the gradient

Question 13

Succinate dehydrogenase

Answer 13

• Complex II in the respiratory cycle
• Makes fumarate from succinate
• An inner mitochondrial membrane protein, sticking out into the matrix side

Question 14

Ubiquinone:cytochrome c oxidoreductase

Answer 14

• Complex III in the respiratory cycle
• Is an inner mitochondrial membrane protein
• Takes quinol and re-oxidizes it back to quinone and dumps it on cytochrome C, a proton which exists in the inner membrane space and picks up electrons from quinone and carries them.

Question 15

Cytochrome oxidase

Answer 15

• Complex IV in the respiratory chain
• Cytochrome C in the inner membrane space becomes re-oxidized, and it puts electrons onto O2 in the cytochrome oxidase to become water in the last step of the e- transport chain

Question 16

Proton gradient

Answer 16

• Complexes I, III, and IV reactions are all pushing protons across the membrane out into the inner membrane space
• This is creating a net positive charge outside of the matrix and a net negative charge inside the matrix
• Basic idea: a very few number of protons being pushed across the gradient can make a lot of ATP

Question 17

Proton motive force

Answer 17

• Complexes I, III, and IV are acting as proton “pumps”, using the ∆G from their reactions to push the protons against the gradient
• The proton motive force is governed by the difference in pH between the inner membrane space and the matrix, and the difference in concentration? between the two

Question 18

Outer membrane

Answer 18

-Contains porins that are permeable up to MW of 5000, so up to small proteins, but mainly glucose and other metabolites and small particles

Question 19

Inner membrane

Answer 19

• Impermeable to most small molecules
• Respiratory chain complex is part of the inner membrane?
• ATP/ADP translocases that switch ATP to ADP and vice versa and other transporters on the inner membrane to only let select things in
• ATP synthase is also in this

Question 20

Matrix

Answer 20

• Has the pyruvate dehydrogenase complex, the Krebs cycle enzymes, and lot of other things, since the Krebs cycle, the pentose phosphate pathway?, beta-oxidation,

Question 21

Ubiquinol

Answer 21

-The fully reduced form of ubiquinone

Question 22

Why can an ordered series of E values predict a chain of electron transport?

Answer 22

• Because it makes sense for the order to go from molecules who are prone to give up electrons (get oxidized, negative E) to molecules who are prone to accept electrons (get reduced, positive E)