electron transport chain KRQ Flashcards
- Where are the proteins and enzymes required for the electron transport chain found?
They are attached to the inner folded membrane (cristae) of the mitochondria.
- Which types of cells have more densely packed cristae and why?
Metabolically active cells such as muscle, liver and epithelial cells because they need to carry out greater respiration so have more surface area for the proteins involved in the electron transport chain and ATP synthase enzymes.
- What happens to reduced NAD and FAD at the start of the electron transport chain?
They lose their hydrogen atoms and become oxidised.
- What happens to the electrons from the hydrogen atoms?
They are lost from the hydrogen (so the hydrogen atoms become ions) and are the electrons are passed along the electron transport chain.
- What is the energy from the transport of electrons along the chain used for?
Pumping hydrogen ions into the intermembrane space (the gap between the inner membrane and the outer membrane)
- What happens to the electrons in the final protein of the electron transport chain?
It combines with molecular oxygen and hydrogen to form water. Oxygen is the final electron acceptor.
- How is the steep concentration gradient of hydrogen ions used by ATP synthase?
ATP synthase has a hydrogen channel which the hydrogen ions pass through, energy from the movement of hydrogen ions is enough to ADP and Pi to produce ATP.
Hydrogen ions (protons) diffuse down an electrochemical gradient through molecules of the enzyme ATP synthase which are embedded in the membrane, this activates ATP synthase to produce ATP.
- What is the difference between substrate level phosphorylation and oxidative phosphorylation of ADP?
Substrate level phosphorylation happens when phosphate groups are transferred from other molecules (e.g. Triose phosphate in glycolysis) whereas oxidative phosphorylation
is the transfer of electrons along the electron transfer chain and production of ATP by ATP synthase due to the diffusion of hydrogen ions through ATP synthase (chemiosmosis)
- How many molecules of ATP are produced per NAD and FAD?
3 or 2.5 and 2 or 1.5
- What is the total number of ATP produced during aerobic respiration?
Approx. 38
- Why is it important that oxygen is present for the ETC to continue?
Oxygen is the final electron acceptor, and if the electrons cannot move down the ETC, no hydrogen ions will be pumped across the membrane. This leads to no gradient of hydrogen ions, so no chemiosmosis and no ATP production.
- What other respiratory substrates can be used in respiration?
Amino acids are deaminated (the amine group is removed) and then the remaining molecule enters the pathway at an appropriate point according to the number of carbons it has. 3c molecules are converted to pyruvate whilst 4 and 5C molecules are converted to intermediates in the Krebs cycle.
Glycerol from lipids is phosphorylated and converted to triose phosphate and enters glycolysis.
Fatty acids are hydrolysed to 2-carbon fragments which bind to coenzyme A and enter the Krebs cycle.
