Quiz 11 Flashcards
ATP for cellular energy
– Driving enzymatic anabolism and catalysis
– Driving membrane transport proteins
– Driving molecule and macromolecule manufacture
Four Stages of Aerobic Respiration
All this activity takes place in the mitochondrion
Step 1 – Pyruvate Decarboxylation – matrix
Step 2 – Krebs/Citric Acid Cycle – matrix
Step 3 – Electron Transport Chain – cristae
Step 4 – ADP to ATP Phosphorylation – cristae
Oxidative Phosphorylation
combined processes of the Electron Transport Chain and ATP Synthase Phosphorylation
Proton, hydrogen ion and H+
all the same thing
1. Pyruvate Decarboxylation step:
1 NADH and 1 CO2 released to matrix, 1 acetyl group enters Krebs via ACA
2. Krebs Cycle step:
3 NADH, 1 FADH2, 2 CO2 released to matrix; succinic acid is produced as a step and released to the matrix
Electron Transport Chain step:
Transfer of electrons through the ETC produces an abundance of H+ ions
ATP Synthase Phosphorylation step:
ATP produced from matrix supply of ADP byharnessing H+ gradient
The ETC concentrates H+ ions (protons) in the mitochondrial intermembrane space by
a complex process of passing electrons (e–) through the 4
membrane enzyme complexes — I, II, III and IV.
ATP synthase
allows The concentrated H+ in the intermembrane space to leak back into the mitochondrial matrix
This desire of H+ to equilibrate across the membrane concentration gradient
drives the enzyme to phosphorylate ADP to ATP — adding a phosphate group to adenosine diphosphate.
Electron Transport chain
a series of 4 enzyme complexes (along with cofactors — iron-sulfur clusters, metal ions, cytochrome c and ubiquinone)
where is ETC embedded
in the cristae–inner membrane of the mitochondrion
what does the ETC do?
These are large and varying complexes (I, II, III,IV) remove electrons from hydrogen which creates H+ for oxidative phosphorylation. They are also H+ pumps.
The primary pathway is I - III - IV.
(80% of electrons are transferred here)
Complex I begins the transport of electrons, which then pass through ubiquinone (coenzyme Q10), Fe-S clusters, Complex III, Cytochrome C, and Complex IV respectively.
The second pathway II - III - IV
succinic acid passes electrons to Complex II, then to ubiquinone, to complexes III and IV.
The electrons are finally reacted with oxygen in complex IV,
forming water. Thus oxygen, as O2, is utilized in two different
steps two different ways in aerobic respiration.
Complex I is NADH
It performs several operations to move electrons, using flavin mononucleotide (FMN) and Fe-S clusters as cofactors. It pumps 4 H+ from the matrixinto the intermembrane space. Additionally, it oxidizes NADH (and FADH2) and passes those hydrogen onto ubiquinone. It hydrolyzes the ubiquinone to ubiquinol (QH2).
Ubiquinone
is a non-polar, vitamin-like coenzyme and
antioxidant, found primarily in mitochondria. It accepts electrons
from NADH dehydrogenase (as hydrogen) and becomes ubiquinol (QH2). Since it is non-polar, it diffuses laterally through the non-polar layer of the cristae membrane and unloads its electrons to Complex III, the Cytochrome bc1 complex.
Iron Sulfur Clusters
are embedded in Complex I, II, and in the Rieske iron-sulfur protein subunit of Complex III. The Fe-S clusters accept the electrons (of hydrogen) from ubiquinol, and pass them into the other subunits of
Complex III.
Cytochrome C
is highly water soluble (polar). This property is utilized in the electron transport chain Cytochrome C moves through the intermembrane space to transport electrons to Complex IV, from Complex III. It carries 1 electron with its iron-heme center.
Cytochrome C Oxidase (complex IV)
This enzyme complex takes O2 and uses it as an electron acceptor — neutralizing the transported electrons from Complex I & III by making H2O from O2 and H+. Thus, there is a second use of oxygen in aerobic respiration as an electron acceptor.
NADH
complex I
Cytochrome C Oxidoreductase
complex III
Cytochrome C Oxidase
complex IV
