Terminal respiration Flashcards
How many complexes are there in the ETC
4
what is terminal respiration
oxygen is the final acceptor of H+ ions and electrons
FADH+ and NAD+ pass hydrogen ions, via a series of redox carriers called the terminal respiratory system, to oxygen to form water.
complex 1
complex 1 oxidises NADH. High energy electrons are passed from NADH to ubiquinone. They flow through Fe-S centres and at the top of the protein (bit in the membrane) they join with protons to form
ubiquinol (QH2).
H+ pumped into intermembrane space
complex 2
succinate- Q reductase(complex 2) oxidises FADH2 and again high energy electrons are passed through Fe-S centres protein to ubiquinone (Q10). This then becomes ubiquinol –BUT A DIFFERENT (QH2) TO COMPLEX 1– once it gets the electrons.
what does ubiquinone sit next to and what is this thing’s purpose?
it sits next to a haem group
this acts as a ‘trap door’ to stop electrons from going somewhere else (this leakage could form free radicals and lead to cancer)
point mutation in complex 2 protein near haem group causes what?
mutation causes haem group not to sit as it should and is at a slight different angle so electrons can leak out and this can lead to benign tumours
What is ubiquinone?
it captures electrons
- a dietary supplement believed to reduce free radicals and thus act as an antioxidant
complex 3
takes the electrons from complex 2 ubiquinol and transfers them to cytochrome c
1 oxidised QH2: 2 reduced cytochrome c
in QH2 there are 4 electrons- 2 go to one cytochrome c molecule and 2 go to the other
this movement flow of electrons to differen molecules results in H+ BEING PUMPED INTO INTER MITOCHONDRIAL MEMBRANE SPACE
Complex 4
takes the electrons from cytochrome c molecules and transfers them to molecular O2 (final acceptor) to make H20
electrons are channeled through Fe-Cu centre ALSO PUMPS H+ INTO INTERMEMBRANE SPACE
Which complexes result in H+ being pumped into intermembrane space?
1,3 and 4
how is energy that is being stored up in the H+ gradient used?
- electron motive force- in this case proton gradient- will kick in and flow back down gradient to release energy to do work
- molecular turbine- ATP synthase
what is chemiosomosis
the movement of H+’s from matrix to intermembrane space (due to electrons moving through E.T.C)
what word is used to describe the movement of electrons through the complexes.
vectoral- particular spatial directionality
what is ATP synthase?
a large multi-unit protein complex that protons can pass back through
what is the name of the mechanism ATP uses to allow return flow of protons?
binding change mechanism
what is the final step in metabolising the food molecules we eat into energy?
ATP taking the potential energy from H+ protons to do work in the cells of the body
What are the two parts that make up ATP synthase?
F0- membrane bound proton conducting unit (top part)- has 10 subunits
F1- protrudes into the matrix and acts as the catalyst for ATP synthesis- produces a lot of ATP
how does the binding change mechanism work?
3 protons move into the F0 part separately
and it clicks round 3 individual times after this it clicks round too much and gets sprung to the next beta subunit
- ADP and Pi then binds into the active site and another 3 H+ go in with 3 more clicks.
Catalysis then occurs and ATP is made- another 3 H+ go in and ATP is kicked out
every time an H+ comes in one has to go out so if 3 come in 3 go out into matrix
what are the 3 states of the active site
- empty
- has ATP ready to shove out
- has ADP and Pi ready to react
what is responsible for the binding change mechanism proceeding?
the physical movement of the central shaft protein but the - (F0) intermembrane part twisting causes the movement of the shaft.
on which subunits do the ADP and Pi subunits bind
beta subunits
there is sequential conformational changes of the beta subunits
what is the shaft for?
ADP and ATP bind to beta subunits in the shaft
H+ don’t go into the shaft they just enter the F0 part and leave it
electron transport is said to be coupled to what process?
ATP synthesis
what is the energy released from e-s passing through E.T.C released as?
heat
malignant hypothermia is caused by what
‘leaky’ mitochondrial membranes that uncouple electron transport and ATP synthase as it is then permeable to H+ ions and no gradient can be made
muscle cells become irreversibly damaged from the excessive heat build up
