Citric Acid Cycle Flashcards
Where does the citric acid cycle occur?
matrix of the mitochondrion
What is the function of the citric acid cycle?
to produce NADH and FADH2 to be used to make energy
feed in system for any molecule that can be converted to an acetyl group
What does the citric acid cycle do specifically?
removes electrons and passes them onto NADH and FADH2
How is acetyl CoA made?
from pyruvate through the action of pyruvate dehydrogenase
What 2 products is acetyl CoA oxidised to?
CO2 and H20
How is pyruvate dehydrogenase regulated?
by its immediate products
by the end point of cellular respiration - ATP
What is the difference between utilisation of glycogen in liver and in skeletal muscle tissue?
liver glycogen—-G-6-P—glucose-6-phosphatase—–glucose in blood
skeletal muscle glycogen—G-6-P—–glycolysis—-lactate
Where is the site of terminal respiration?
mitochondrion
Where is the majority of NADH and FADH2 formed? Where is the rest of it formed?
majority in citric acid cycle
rest in cytosol
What is the glycerol phosphate shuttle?
mechanism by which cytosolic NADH passes its electrons onto glycerol-3-phosphate and then to FADH2 for use in the electron transport chain
What is the disadvantage of using cytosolic NADH?
FADH2 generates less energy per mole than oxidation of NADH itself
There are 4 protein complexes involved in the electron transport chain. What does complex 1 do?
oxidises NADH and passes high energy electrons onto ubiquinone to form ubiquinol
pumps H+ ions into the inter membrane space
What does complex 2 do?
oxidises FADH2 and passes high energy electrons onto ubiquinone to form ubiquinol
What does complex 3 do?
takes electrons from ubiquinol and passes them onto cytochrome c
oxidation of one ubiquinol yields 2 reduced cytochrome c molecules
pumps protons into intermembrane space
What does complex 4 do?
takes electrons from cytochrome c and passes them onto oxygen
pumps protons into inter membrane space
How is the energy saved up in the H+ gradient used?
- proton motive force
2. ATP synthase ‘turbine’ evolved to harness energy from proton gradient
What is chemiosmosis?
the process by which protons are pumped into the inter membrane space as electrons are passed along the transport chain
What is a proton motive force?
when the protons are allowed to flow back down their gradient and release energy in the process
How is ATP synthesised?
protons move by proton motive force back down their gradient back into the matrix of the mitochondrion——– this only happens at certain areas on the membrane and at these sites there is often ATP synthase—– as the protons flow through the ATP synthase, the energy stored in the gradient is used to convert ADP + Pi to ATP
ATP synthase has two parts. Name them and describe what they do.
F0- membrane bound proton conducting unit
F1- protrudes into the mitochondrial matrix and acts as a catalyst for ATP synthesis
How much ATP is produced per H+?
3H+ moved across the membrane by ATP synthase + 1 ATP
What are the end products of terminal respiration?
CO2, H2O and ATP
Explain the concept of coupling in relation to oxidative phosphorylation?
electron transport is said to be ‘coupled’ to ATP synthesis
this is because, if the inner mitochondrial membrane becomes permeable to protons, the proton gradient cannot be generated, but the electrons can still be passed along their carriers
therefore O2 still reduced to O2 but no ATP made
What does it mean for the processes to be uncoupled?
when the inner mitochondrial membrane becomes permeable to the H+ ions and the proton gradient cannot be generated therefore ATP synthesis doesn’t occur but electron transport chain still occurs
energy from ETC is released as heat
