Bioenergetics

Question 1

which membrane of the mitochondria is more selective

Answer 1

inner

Question 2

what is the minimum size of the intermembrane space in mitochondria

Answer 2

10nm

Question 3

what proteins are involved in mitochondrial fusion
what are their roles

Answer 3

mitofusin (Mfn) 1 and 2: have complementary binding motifs that allow fuse the outer membranes
optic atrophy 1 protein (OPA1): similar for inner membrane

Question 4

what protein is involved in mitochondrial fission
what is its role

Answer 4

cytoplasmic GTPase (Drp1): triggered by ER fusion, forms a ring that constricts

Question 5

what do mutations in Mfn2 and OPA1 lead to

Answer 5

Charcot-Marie-Tooth neuropathy

Question 6

what does dysfunction of mitochondrial fission/fusion proteins lead to

Answer 6

mitochondrial defects that lead to neurological disease
due to high energy demands

Question 7

why is mitochondria degredation common

Answer 7

the types of reaction that happen in mitochondria
reactive oxygen species generated by complex 1 can cause damage

Question 8

explain the PINK1 mitochondria degredation pathway

Answer 8

• membrane anchored kinase cycled from outer to inner membrane
• then cleaved by inner membrane protease (Parl)
• if the inner membrane is damaged there is a PINK1 build up at outer membrane
• E3 ubiquitin ligase activates and ubiquitinates VDAC
• mitochondria is encased in a lysosome and degraded

Question 9

what does mutations in the mitochondria degredation pathway lead to

Answer 9

Parkinson’s

Question 10

what is the degredation of mitochondria called

Answer 10

mitophagy

Question 11

electrochemical properties of IMS and matrix of mitochondria

Answer 11

IMS is more positive and acidic
matrix is more negative and alkali

Question 12

what are flavins
how many ______ can they carry at a time
key example

Answer 12

a class of molecule that are co factors for electrons
2
FADH2

Question 13

how do electrons flow from one complex to another within the membrane

Answer 13

carried by quinones

Question 14

explain the losses in terms of energy in the mitochondria

Answer 14

the Adenine Nucleotide Exchanger transports ADP in and ATP out of the matrix
this means two negative charges in but three out
hence a loss of the electrochemical gradient (IMS meant to be more +ve)

Question 15

explain ATP uncoupling

Answer 15

uncoupling ATP synthesis from the flow of protons
the inner membrane is made permeable to to H+ by a pore or channel allowing the flow of protons down their concentration gradient
leads to thermogenesis