L13A: TCA Cycle as a Metabolic Hub & L13B: OXPHOS- Transferring Bioenergy for ATP Synthesis Flashcards
from the TCA cycle, how many ATPs does the cell make per glucose
10 NADH = 30 ATP
2FADH2 = 4 ATP
Substrate level phosphorylation = 4 ATP
SO ANS = 1 glucose yields 38 ATP max if completely oxidised to CO2 & H2O
what are metabolites constantly feeding into TCA for
for fat degradation
what are metabolites constantly feeding out of TCA for
for synthesis
what TCA metabolites are oncometabolites & promote tumorgenesis
succinate & fumarate
which TCA metabolites alter the response of the innate & adaptive immune systems
acetyl-CoA
succinate
fumarate
the 3 exergonic irreversible enzymes in TCA
- citrate synthase
- isocitrate dehydrogenase
- alpha-ketoglutaric dehydrogenase
rate limiting step TCA
accumulation of isocitrate
what are the 3 exergonic irreversibe enzymes in tCA regulated by
allosterically by:
* energy indicators
* product accumulation
* substrate availability
enzymes off when NADH & ATP @ high conc
enzymes off by low energy indicators - NAD+, AMP, ADP
what e- carriers transfer e-s to respiratory chain & fuels ATP synthesis in mitochondria
NADH & FADH2
which part of the mitochondrial membrane is permeable to small molecules
outer membrane freely permeable to smalll molecules & ions but inner membrane is not
what happens to the e-s from reduced coenzymes
they are removed & passed along a series of membrane bound carriers
movement of e-s is a series of redox rxns
significance of the movement of e-s being a series of redox rxns
- redox rxns are exergonic
- free energy made available by rxns used to pump protons (H+) to intermembrane space to establish potential gradient
what rectifies the deficit in potenial gradient in intermembrane space by providing a channel through which protons can pass out into matrix
making ATP
how many protein complexes in ETC
5
OXPHOS overall
- cells use energy from flow of e-s to pump H+ ions across a membrane
- energy of H+ gradient used to make ATP
- done in presence of O2
what does all catabolism in presence of O2 converge to
oxidative phosphorylation
3 types of e- transfer in OXPHOS
- direct transfer of e-s (Fe3+ + e- = Fe2+)
- transfer as hydrogen ion (H+ + e-)
- transfer as hydride ion
apart from NAD, FAD and FMN, what are the 3 other types of e- carrying molecules in OXPHOS
- Ubiquinone
- Iron-Sulfur proteins
- Cytochromes
what in Ubiquinone can accept 1 or 2 e-s as hydrogen
the quinone ring structure
what are cytochromes
proteins with iron containing heme prosthetic groups
how many iron sulfur proteins work in the ETC
at least 8
OXPHOS e- carrier sequence
NADH
Flavoprotein
Ubiquinone
Fe-S Centres
Cytochromes
Finally, O2
