Sessions 13 and 14 - ETC and Ox Phos Flashcards
compare the electron carrier component in both flavin mononucleotide (FMN) and flavin dinucleotide (FAD)
they are both the same (top middle nitrogen and bottom right nitrogen)
does FADH2 feed its electrons before or downstream of the electrons released from NADH
they’re released downstream because the NADH electrons have a higher reduction potential. the FADH2 derived electrons pump fewer protons and thus yield fewer molecules of ATP
how does iron function in the ETC
iron is a prominent electron carrier appearing either associated with sulfur in iron sulfur complexes or as a component of a heme-prosthetic group in a special class of proteins called cytochromes. iron shuttles between its reduced form FE2+ and its oxidized ferric state FE3+
what is distinct about coenzyme Q as an electron carrier
in the fully oxidized state Q, coenzyme Q has two keto groups. the addition of one electron yields a semiquinone radical anion Q * - whereas the addition of one electron and one proton generates semiquinone (QH). the fully reduced form with the addition of another electron and proton is ubiquinol and thus for quinones, electron-transfer reactions are coupled with proton binding and release
name the 3 large protein complexes through when electrons are transferred through from NADH to O2 in greatest to lowest free energy
NADH-Q oxidoreductase, Q-cytochrome c oxidoreductase, and cytochrome c oxidase. these 3 are the proton pumps
how many protons do the 2 electrons transferred to Q through proton pump I pump across the membrane
the 2 electrons pump 4 hydrogen ions out of the matrix of the mitochondrion
what is the entire equation for reduced cytochrome c to oxidized cytochrome c and water
4 Cyt c-red + 8 H+ - matrix + O2 –> 4 Cyt c-ox + 2 H2O + 4 H+ - intermembrane space
where are Fo and F1 subunits of ATP synthase located
Fo is embedded in the inner mitochondrial membrane while F1 resides in the matrix
what contains the proton channel of the complex
Fo
what is F1 composed of
a3, b3, y, o, and e subunits. the 3 a and 3 b are arranged alternatively in a hexamer ring. the active sites reside on b subunits. the y and e subunits make up the central stalk. the y subunit includes a long helical coiled coil that extends into the center of the a3b3 hexamer
what is distinct about b subunits
each of the b subunits is distinct because each interacts with a different face of the y subunit
what contains the proton channel of the complex
Fo
describe the rotation of the hexamer and the 3 b subunit states O, L, and T
T is the active site where ADP + Pi becomes ATP. once this transformation occurs the hexamer spins 120 degrees so that the ATP is now in the O position. ATP is released and ADP + Pi takes its place. at the same time as this exchange is occurring the former L position is now in the T position and is becoming ATP. another 120 degree spin and the former O position where the ATP was released is no in the L position locking the ADP + Pi into place.
describe the process of a proton moving across the membrane through the c ring
a proton enters from the intermembrane space into the cytoplasmic half-channel to neutralize the charge on a glutamate or aspartate residue in a c subunit. with the charge neutralized, the c ring can rotate clockwise by one c subunit, moving the amino acid residue out of the membrane into the matrix half-channel. this proton can move into the matrix then. each proton enters the cytoplasmic half-channel, follows a complete rotation of the c ring, and exits through the other half-channel into the matrix
how is cytoplasmic NADH reoxidized to NAD+ as the inner mitochondrial membrane is impermeable to it
the solution is that electrons from NADH, rather than NADH itself are carried across the mitochondrial membrane.
