18.6 part 1
How are the 30 molecules of ATP from complete glucose combustion formed?
26 come from ETC
glucose in metabolized to 2 pyruvates which generate 4 ATP
when glucose in fermented, only 2 ATP produced per molecule
What happens when ETC is inhibited?
proton-force gradient not generated
ETC uncoupled from ATP synthase
inhibition of ATP synthase
ATP export inhibited
What does the pentose phosphate pathway do and how does it work?
Generates NADPH and synth. 5 carbon sugars in cytoplasm
1st phase: oxidative gen. of NADPH
2nd phase: non-ox interconverting phosphorylation of 3,4,5,6,7 carbon sugars
What happens to ribulose 5 phosphate and what kind of rxn is it?
isomerized into ribose 5 phosphate via phosphopentose isomerase
reversible rxn
What are the steps of the transketolase rxn mechanism?
1. TPP forms carbanion
2. carbanion attacks ketose substrate
3. C-C bond is cleaved and aldose prod. is released, TPP binds to 2-C fragments and glycoaldehyde intermediate is formed
4. intermediate attacks aldose substrate
5. ketose prod is released and TPP is ready for another cycle
What determines the rate of ETC, why, and what is it known as?
need for ATP
e- cannot be transferred through ETC if ADP isn't available to be converted to ATP
ADP is respiratory control
What happens in mitochondrial disease?
complex 1 doesn't function properly
ATP synthesis is reduced
ROS and mitochondrial damage are increased
What pathways require NADPH?
synthesis: fatty acid, cholesterol, neurotransmitter, nucleotide
detoxification: red. of ox. glutathione, cyt. p450 monooxygenases
What is the non-oxidative phase and what are the components of the reactions?
made up of 3 rxns
C5 + C5 to C7 + C3 transketolase
C3 +C7 to C4 + C6 transaldolase
C4 + C5 to C6 + C3 transketolase
What are the steps of the transaldolase rxn mechanism?
1. Schiff base forms between enzyme and ketose substrate
2. Schiff base is protonated and aldose prod is released
3. substrate enzyme intermediate is formed
4. 3 carbon fragment bond to enzyme and add to aldose substrate
5. Deprotonation
6. hydrolysis of Schiff base releases ketose prod
Describe the respiratory control trend
As time goes on ADP decreases and O2 increases
What is apoptosis and how does it function?
cell programmed death that is necessary for remodeling
mitochondria controls it and makes its membrane more permeable for dead cells to leave through death pathways made by cytochrome c
What are the roles of glucose 6-phosphate dehydrogenase?
starts ox. phase and converts glucose 6-phosphate to 6-phosphoglucano - delta- lactone
reduces NADP+ to NADPH
generates a second NADPH to convert 6-phosphoglucanate to riblous-5-phosphate + CO2
What is Xylulose 5-phosphate, how is it formed and what type of rxn is it?
substrate for transketolase rxn
formed from ribulose 5- phosphate and phosphopentose epimerase
reversible rxn
What is IF1, what does it do, and what does an over-expression cause?
highly conserved protein that inhibits hydrolysis of ATP synthase
prevents hydrolysis when not enough oxygen to accept e-
leads to over-expression in cancer which causes aerobic glycolysis
What is LHON and why does it occur?
vision loss due to optic nerve death with an abnormally shaped optic nerve
due to mitochondrial gene mutation where pro is sub for lys
caused by decreased ATP and increased ROS
What is the oxidative phase scheme?
(refer to picture)
What is the sum of the nonoxidative rxns?
converts 3 5 carbon sugars to components of glycolytic and glycogenic pathways
What is non-shivering thermogenesis, what does it impact?
When e- transport is uncoupled from ATP synthase and heat is generated
UCP 1 does this and is an integral membrane protein
found in BAT
obesity decreases BAT
UCP 2 and 3 regulate body weight and homeostasis
What is the ETC inhibition flow scheme and what are the blockers and their locations?
NADH to NADH-Q oxidoreductase to QH2 to Q-cytochrome-c-oxidase to cytochrome c to cytochrome c oxidase to O2
blockage from NADH-Q ox. to QH2 by rotenone and amytal
blockage from Q-cyt. to cyt c by antimycin A
blockage from cyt c ox. to O2 by CN- NH3- and CO
What do transketolase and transaldolase do?
link the PPP and glycolysis pathways
What do phosphopentose isomerase and epimerase do?