chapter 20 Flashcards
what is the purpose of the electron transport chain
to capture high energy electrons to synthesize ATP
what occurs in the electron transport chain
the flow of electrons from NADH and FADH2 to O2
what does the electron transport chain consist of
exergonic oxidation-reduction reactions that generate a proton gradient
what makes up cellular respiration
citric acid cycle and oxidative phosphorylation (ETC)
where does the electron transport chain and ATP synthesis occur
in the mitochondria specifically on the inner membrane
where does the citric acid cycle and fatty acid oxidation take place
in the mitochondrial matrix
the outer mitochondrial membrane is permeable to
most small ions and molecules
what channel protein enables the outer mitochondrial membrane to be permeable
mitochondrial porin
the inner mitochondrial membrane is permeable to
almost nothing!!! trick question
what are the folds on the inner mitochondrial membrane called
cristae
the reduction potential (Eo’) or redox potential is a measure of
a molecule’s tendency to donate or accept electrons
a strong reducing agent readily…..
donates electrons and has a negative reduction potential
a strong oxidizing agent readily…..
accepts electrons and has a positive reduction potential
what are the names of the 3 large complexes that pump proteins out of the mitochondria generating a proton gradient
NADH-Q oxidoreductase (complex 1)
Q-cytochrome c oxidoreductase (complex 3)
cytochrome c oxidase (complex 4)
what type of molecule are the 3 large complexes
proton pumps
what is complex 2
succinate-Q reductase
what does complex 2 do
delivers electrons from FADH2 to complex 3
is succinate-q reductase (complex 2) a proton pump
NO NO NO NO
what does coenzyme Q do
-derived from isoprene
-binds protons (QH2) as well as electrons and can exist in several oxidation states
what is the Q pool
oxidized and reduced Q molecules that are present in the inner mitochondrial membrane
what is cytochrome C
an electron carrier that employs an iron incorporated into heme
what does cytochrome C do
carries electrons from complex 3 to complex 4
in general, what are cytochromes
electron-transferring proteins that contain a heme prosthetic group
what does the heme iron cycle do
cycles Fe2+ and Fe3+ as it accepts or donates electrons
what are iron-sulfur proteins
-also called nonheme iron proteins
-are prominent electron carries
-contain various types of iron-sulfur clusters
what is the difference between iron-sulfur proteins and cytochrome c
cytochrome c and cytochromes in general contain heme to cycle iron while iron-sulfur proteins do not contain heme
what is similar about iron-sulfur proteins and cytochromes
they both cycle iron to carry electrons
how do high potential electrons of NADH enter the ETC
electrons from NADH are passed along to Q to form QH2 by complex I
what happens after complex I receive the electrons from NADH
QH2 leaves the enzyme for the Q pool in the hydrophobic interior of the inner mitochondrial membrane
what are the electron carriers that pass the electrons from NADH to Q
flavin mononucleotide (FMN) and several iron-sulfur proteins
how many protons are pumped out of the mitochondria by complex I
FOUR
what is the entry point for electrons from FADH2 of flavoproteins
ubiquinol
what happens at complex 2
the FADH2 generated in the citric acid cycle reduces Q to QH2 and that then enters the Q pool
what happens at complex 3
electrons from QH2 are used to reduce two molecules of cytochrome c in a reaction catalyzed by complex 3
what two cytochromes are present at complex 3
b and c1
how are electrons transferred from QH2 to cytochrome C
this process is called the Q cycle
what happens in the Q cycle
first half: one electron from QH2 reduces cytochrome c and one reacts with Q to form Q.-
second half: another QH2 reduces cytochrome c and Q.-
what is the result of the Q cycle
4 protons are pumped out of the mitochondria and two more are removed from the matrix
what happens at complex 4 (general)
complex 4 accepts four electrons from four molecules of cytochrome c in order to catalyze the reduction of O2 to two molecules of water
what happens in the cytochrome c oxidase reaction
eight protons are removed from the matrix
four protons, called chemical protons are used to reduce oxygen
four protons are pumped into the intermembrane space
what are ROS
partial reduction of O2 generates highly reactive oxygen derivatives (ROS)
ROS are implicated in many pathological conditions
ROS include superoxide ions, peroxide ions, hydroxyl radicals
what can help protect against ROS damage
superoxide dismutase (SOD)
