Mitochondria and Oxidative Phosphorylation

Question 1

cardiolipin

Answer 1

lipid unique to the mitochondrial inner membrane

Question 2

mitochondrial myopathy

Answer 2

abnormal mitochondria with a disorganizedappearance and crystal structures within

Question 3

voltate-dependent anion channels (VDACs

Answer 3

large non-selective pores on the outer membrane that allow meovement of anions such as phosphate, chloride, pyruvate, citrate, and adenine nucleotides

beta barrel structure hints a bacterial origins of mitochondria

Question 4

mitochondrial genes

Answer 4

mitochondria contain their own DNA and tRNAs

proteins need to bew synthesized in the cytoplasm and then transported into mitochondria

only 13 subunits of the ETC are expressed in the mitochondrial genome

Question 5

import of proteins into the mitochondrion

Answer 5

must have amphipathic

recognized by protein complexes TOM and TIM (transport outer and transport inner membrane

proteins transported as a linear peptide

Question 6

oxidative phosphorylation

Answer 6

the process of using the energy from the electrochemical potential gradient generated by oxidation in the ETC to create ATP from ADP

Question 7

Describe the electron flow through the ETC.

Answer 7

oxygen is the best electron receptor and has the largest positive reduction potential

more energy is released from the oxidation of NADH by O2 than the oxidation of FADH2 by O2 because NADH has a more negative reduction potential than FADH2

Question 8

Complex I

Answer 8

accepts a free proton plus the hydride ion carried by NADH, has an Fe-S center

Question 9

Complex II

Answer 9

does not span the membrane, contains succinate dehydrogenase

takes electrons from FADH2 and passes it onto CoQ

Question 10

Coenzyme Q or ubiquinone

Answer 10

mobile carrier that accepts electrons from complexes I and II and donates them to complex III

linked to a 50 carbon lipid that allows it to diffuse through the membrane

Question 11

complex III

Answer 11

cytochrome proteins have bound heme with an iron atom

electrons are transfered to cytochrome c

Question 12

Complex IV

Answer 12

cytochrome c oxidase

complex passes electrons from cytochrome c to final electron acceptor O2

Question 13

heme a, b, and c

Answer 13

heme a - long isoprenoid tail that can bind to proteins

heme b - more loosely bound

heme c - covalently attached to alpha helices

iron int he middle important for electron transport because can be oxidized from ferric to ferrous state and back

Question 14

ATP synthase

Answer 14

a protein that acts like a motor to add phosphates onto ADP to make ATP, uses the proton motive force

couples energy of proton movement with conformational changes to carry out the reaction

Question 15

adenine nucleotide translocase (ANT)

Answer 15

exchanges ATP and ADP in a 1:1 exchange

Question 16

Name the five major mitochondrial inner membrant transporters.

Answer 16

ATP-ADP translocase, dicarboxylate carrier, tricarboxylate carrier, pyruvate carrier, phosphate carrier

Question 17

What are the two methods of transporting electrons into the mitochondria?

Answer 17

glycerol 3-phosphate shuttle and malate-aspartate shuttle

Question 18

Describe the glycerol 3-phosphate shuttle.

Answer 18

major shuttle in most tissues

Question 19

Describe the malate-aspartate shuttle

Answer 19

cytosolic NADH is necessary for shuttle function

Question 20

Describe the creatine phosphate shuttle.

Answer 20

muscle needs high ATP, needs a way to keep cytosolic ATP low but also store energy for action

prevents ATP from being used up by other processes

Question 21

mitochondrial permeability transition pore

Answer 21

mitochondria become more permeable to small molecules, leads to mitochondrial swelling and cell death through apoptosis or necrosis

Question 22

uncoupling proteins (UCP)

Answer 22

found in the inner mitochondrial membrane, creating a proton leak without generation of ATP

energy is released as heat, up to 20% of adult resting metabolic rate is due to energy expended to restore proton gradients lost to UCPs

babies have brown fat that have UCPs to generate heat

Question 23

2,4-dinitrophenol

Answer 23

compound that can uncouple OXPHOS because it transfers protons across the inner membrane down their concentration gradient

Question 24

How do the following inhibitors affect the ETC? - cyanide, carbon monoxide, hydrogen sulfide, and sodium azide

Answer 24

bind to the iron in the heme of the cytochrome aa3 component of cytochrome oxidase, preventing electron transfer to O2

Question 25

How does antimycin affect the ETC?

Answer 25

it binds to cytochrome c reductase in complex II, inhibiting the oxidation of CoQ in the electron transport chain of oxidative phosphorylation

Question 26

Howe do barbituates such as Amytal and Rotenone affect the ETC?

Answer 26

inhibit the transfer of electrons from iron-sulfur centers in Complex I to CoQ

Question 27

How does atractyloside affect the ETC?

Answer 27

inhibits the ADP-ATP transporter in the inner membrane

Question 28

How does oligomycin affect the ETC?