M104 T2 L4 (theory not diagrams) Flashcards
What is the electron transport chain otherwise known as?
the respiratory chain
How is the long isoprenoid tail of coenzyme Q beneficial?
allows coenzyme Q to be soluble in the membrane
How do the soluble linking proteins of the e- transport chain move in the membrane?
they are free to move in the membrane by diffusion, rather than being part of the complexes
How many sub units is Complex 1 made up of?
44 different sub-units
Why is the ETC fully dependent on o2 availability?
bc oxygen functions as the final acceptor of electrons. - it is needed at the last stage for Complex 4 to work
What are the ionic chargest of ADP and ATP?
ADP = -3 ATP = -4
What is atractyloside an inhibitor of?
adenine nucleotide translocase
What are the two functional domains of ATP synthase?
Fo, a proton channel
F1, an ATP synthase
What is the role of ATP synthase?
required for ATP synthesis
What does Fo represent?
an oligomycin-sensitive proton channel
What does F1 represent?
an ATP synthase
Where are the Fo and F1 domains of ATP synthase located?
Fo- is embedded in the inner mitochondrial membrane
F1 - sticks out of the inner mitochondrial membrane and into the matrix
How is Fo divided?
into three different types of subunit: a, b, and c
How many subunits are in each complex of Fo?
13-15 subunits
What is special about subunits c1-10 in Fo?
their arrangement is circular
How is F1 divided?
five subunits
What are the five different subunit types in F1?
alpha-3 (x3 subunits) beta-3 (x3 subunits) gamma delta epsilon
How many subunits are in each complex of F1?
nine subunits
What is special about the beta-3 subunits in F1?
they have catalytic sites for ATP synthesis
What is the arrangement for alpha and beta subunits in F1?
they are alternately arranged
circular arrangement like segments of an orange
forms a knob-like structure held by a stalk of the gamma and epsilon subunits
What does the theory of rotational catalysis describe?
the three beta subunits of F1 taking it in turns to catalyse the synthesis of ATP
What happens during the theory of rotational catalysis?
Any given beta subunit starts in a conformation for binding ADP and Pi
the beta subunit then changes conformation so the active site now binds the product ATP and Pi more tightly
a further change in conformation lowers the active site’s affinity for ATP (‘beta-empty’ conformation)
this allows the ATP to be released
What is the effect of the gamma-unit rotating?
it changes the properties of the beta-catalytic units
they are no longer able to bind the raw materials (ADP and Pi)
What is the rotation of the F1 subunit of ATP synthase driven by?
its driven by the E harnessed from H+ ions re-entering the matrix from the intermembrane space
What is the final yield of ATPs per one molecule of glucose via the ETC?
either 30 or 32 molecules of ATP
What is the role of uncouplers?
to allow H+ ions back into the matrix of the mitochondria by channels other than ATP synthase (bypassing)
to sever the link between e- flow and ATP synthesis, with the E being released as heat
What is an example of an uncoupler?
DNP
How can the uncoupling of oxidative phosphorylation occur?
naturally - UCP1 (found in mitochondria)
pharmacologically - DNP
Where is UCP1 found?
in brown adipose tissue
What is special about UCP1?
it has a specific H+ channel through which the [H+] may be dissipated - E released as heat
What is a unique feature of brown adipose tissue?
has high numbers of mitochondria
What is brown adipose tissue specialised for?
heat generation
In what groups of people is brown adipose tissue important for?
new-borns (they’re very susceptible to hypothermia)
has a possible role in obesity / diabetes
What is the history of DNP?
was used in the 1930s as a slimming drug
it’s toxic - is now used as a pesticide
What causes DNP to be toxic?
liver damage, respiratory acidosis and hyperthermia
What are the names of the different complexes?
complex I: NADH dehydrogenase
complex II: Succinate dehydrogenase
complex III: Coenzyme Q - cytochrome c oxidoreductase
complex IV: Cytochrome oxidase
