Ox Phos Agbas Flashcards
Describe the ultrastructure of the mitochondria
oval shaped organelles with two membrane systems
Outer membrane is permeable to most small molecules due to porins (VDAC-voltage Dependent Anionic Channels)
Inner membrane is impermeable and has metabolite transporters
Two compartments
- Intermembrane space
- Matrix(TCA and faty acid oxidation)
Where does ox phos occur?
In the inner membrane of the mitochondria
Describe the history of the mitochondrial genome
Data has narrowed it down to one bacteria, Rickettsia prowazekii, from a single endosymbiotic event
Human mitochondrial DNA has 16569 bp and 13 respiratory chain proteins
maternally inherited
What is the goal of Ox Phos?
- Takes the NADH and the FADH2 from the TCA cycle and flows them through 4 complexes in order to reduce molecular O2 to water
- proteins are pumped to the intermembrane space (proton gradient)
- Return through the ATP synthase to make more ATP
Describe Complex 1 of the ETC
NADH dehydrogenase or NADH-Q oxidoreductase
Large protein that is encoded by nuclear and mitochondrial genes
Has iron sulfur clusters throughout that help with the reduction reactions
FIRST point of entry for NADH
Describe complex II
Succinate-Q reductase complex
connects TCA to Oxphos
FADH2 delivers its electrons here where they are transferred to Fe-S then to Q and then QH2
No proteins are pumped
leads to less ATP yielding
Describe complex III
cytochrome c reductase
Takes the electrons from QH2 and then passes it to cytochrome c
2 protons are pumped across tot he cytoplasmic side
Describe Complex IV
Cytochrome c oxidase
Last complex: transfers electrons from the reduced cytochrome c and delivers them to O2 to make water
makes the process aerobic and allows humans to breathe
4 electrons are used in order to reduce O2 to water
protons pumped to the matrix
Define the respirasome.
Made up of complexes I, III, and IV.
Describe coenzyme Q
Also known as ubiquinone
Transfers electrons from complex I and complex II to complex III
The enzyme has a series of 5C isoprene tails that make it hydrophobic
CoQ 10 is most common
Describe cytochrome c
Electrons are taken from III to IV
final component
Catalyzes the reduction of O2
Describe the flow of energy along the ETC
Starts at a high free energy (negative) and decreases (positive Eo) as it continues
Describe free radicals in detail and tell what is affected if they are released (RNS and ROS)
Free radicals are the result of a partial reduction of O2 (superoxide ion (O2(-)) and peroxide (O2(2)))
Superoxide ion can lead to Arg oxidation which leads to the production of RNS and peroxide ion will lead to ROS
An OVERPRODUCTION of either of these will damage lipids, proteins, and DNA
List a few BIG players in regards to free radical pathologies
- Parkinsons
2. Diabetes
Describe the defensive mechanisms that are in place within the body that help to control reactive oxygen species
Superoxide dismzutase (SOD) takes an oxygen radical and two protons and turns it into oxygen and hydrogen peroxide
Catalase takes hydrogen peroxide to oxygen and water
Describe the various actions of superoxide dismutase
- SOD1 contains a copper and zinc and is found in the cytoplasm
- SOD2 has a maganese and Zinc, that is located in the mitorchondria
Describe the different ways in which the body can get rid of ROS (in regards to gen chem)
ROS can be reduced to form hydrogen peroxide or oxidized to form O2
Describe the prosthetic groups of NADH-Q oxidoreductase
There are two, Fe-S and FMN.
The electrons enter the chain through this enzyme and the transfer occurs via the FMN prosthetic group which leads to the formation of FMNH2
These electrons then travel to the Fe-S clusters in order to continue along the chain
Describe the prosthetic groups of the succinate Q-reductase
There are two; FAD and Fe-S
The electrons from the citric acid cycle FADH2 are transferred to the Fe-S clusters (FAD is in there somewhere so just know its there)
Describe the prosthetic groups that are present in the Q-cytochrome c oxidoreductase
There are 3 hemes
Heme BL- L stands for a low affinity and is closes to the cytoplasm
Heme BH- H stands for high affinity which is near the matrix side
Heme C1
And there are also Fe-S clusters
Describe the prosthetic groups that are present with in the cytochrome c oxidase
Heme a: formyl group (instead of a methyl in the cyto c oxidoreductase), C17 replaces a vinyl group, and heme cannot be covalently attached
