lecture 5: cellular respiration Flashcards
what happens to the reactants of cellular respiration?
-C6H12O6 gets oxidized to CO2
-O2 gets reduced to H20
what is cellular respiration?
4 step process that gradually breaks down glucose
why is cellular respiration a redox reaction?
-because glucose is oxidized (loses electrons). glucose gives its electrons to O2
because O2 is reduced
what is the reaction for cellular respiration?
what are the electron carriers in cellular respiration?
NADH and FADH2
which steps of cellular respiration strip glucose of its electrons and transfer them to NAD+ and FAD?
glycolysis, pyruvate oxidation and the citric acid cycle
what are the 2 ways to make ATP in cellular respiration?
-substrate level phosphorylation
-oxidative phosphorylation
what is substrate level phosphorylation? when does this happen?
-enzyme catalyzes the transfer of a phosphate group to ADP from a substrate (gives the substrate’s phosphate group to ADP, which forms ATP
-glycolysis and citric acid cycle
what is oxidative phosphorylation? when does this happen?
-chemiosmosis powers the production of ATP by ATP synthase
-electron transport chain (ETC)
how many ATP does a single glucose molecule produce?
32
where does glycolysis happen?
cytosol of the cell
which parts of cellular respiration occur in the mitochondria?
pyruvate oxidation, citric acid cycle, electron transport chain
which step of cellular respiration does not produce ATP?
pyruvate oxidation
What is the reaction equation for glycolysis?
What is the reaction for pyruvate oxidation?
What is the reaction for the citric acid cycle?
What is the reaction for the electron transport chain?
how many phases does glycolysis have?
2
what are the 2 phases of glycolysis?
-energy requiring phase (need ATP)
-energy producing phase (produces ATP)
what exactly happens during the energy producing phase of glycolysis?
What exactly happens during the energy requiring phase of glycolysis?
What does the input of products/reactants look like in the energy requiring phase of glycolysis?
What does the input of products/reactants look like in the energy producing phase of glycolysis?
What does the net input of products/reactants look like in glycolysis?
what is the coenzyme needed to catalyze pyruvate oxidation?
coenzyme A
after being produced by glycolysis, where does pyruvate go?
it is transported into the mitochondrial matrix and oxidized to acetyl-CoA
how is the amount of carbons conserved throughout pyruvate oxidation?
what is the Krebs cycle/citric acid cycle’s purpose? what is getting oxidized and what is it being oxidized to?
final breakdown of glucose and completely oxidizing it. Acetyl-CoA is being oxidized to CO2
what is the sentence that helps to remember the Krebs cycle?
Crikey, I am so sorry for making oatmeal
where does the krebs cycle take place?
mitochondrial matrix
how many turns does the Krebs cycle do per glucose molecule?
2 cycles, because each glucose molecules produces 2 pyruvate molecules
What is the net products of 2 rounds of the Krebs cycle?
what happens during the electron transport chain?
-energy moves through the ETC from high energy to low energy (spontaneous)
-energy released is used to pump protons into the intermembrane space to generate a proton gradient (pumping protons is non-spontaneous)
what does the electron transport chain (ETC) contain?
where is the electron transport chain?
embedded in the inner mitochondrial membrane
which enzyme complex receives the electrons from FADH2?
complex II
where does the ETC get its electron sources from?
-the electrons are taken from NADH and FADH2, produced during the previous steps of cellular respiration
which enzyme complexes pump protons? how do they pump them?
I, III and IV. Every time an electron moves through complex, it releases energy, which then powers the pumping of one H+
why does complex II not pump protons?
its not bound into the membrane
what is the enzyme in the ETC that allows H+ to regain their concentration gradient. how does this produce ATP?
ATP synthase. H+ moves in this channel, which powers the turbine attached to it and attaches ADP+P together to form ATP
what are the 2 mobile e-carriers?
coenzyme Q and cytochrome C
what type of ATP production is the electron transport train?
oxidative phosphorylation
how many electrons do NADH and FADH2 each give to the complexes?
2
what is the final electron acceptor during electron transport chain?
O2
what does complex 1 do?
-receives electron from NADH
-pumps protons from matrix into inter membrane space
-
what does coenzyme Q do? (ubiquinone)
-receives electron from complex 1 or FADH2 (via complex 2)
-moves in the lipid bilayer (lipid soluble)
what does complex III do?
-receives electron from coenzyme Q
-pumps protons from matrix into intermembrane space
-contains cytochromes
what does cytochrome C do?
receives electrons from complex III. It moves over the ETC, because it is not lipid soluble. passes electrons to complex IIII
what does complex IV do? (CYTOCHROME OXIDASE)
-receives electrons from cytochrome C
-transfers electrons to O2 to produce H2O
-pumps protons from matrix into intermembrane space
-contains cytochromes
what are cytochromes?
-iron containing heme proteins important for the ETC because iron can act as an electron donor or acceptor
What is the reaction that happens within the iron of cytochromes that allows it to be good for cellular respiration?
how many ATP are produced during the electron transport chain cycle?
for 10 NADH and 6FADH2, 28 ATP are produced during this part of cellular respiration
which reactions produce the 6 CO2 total for cellular respiration? how many CO2 does each reaction produce?
-2 CO2 from pyruvate oxidation
-4 CO2 from citric acid cycle
which reactions produce the 32 ATP molecules total for cellular respiration? how many ATP molecules does each reaction produce?
-2ATP from glycolysis
-2 ATP from Krebs cycle
-28 ATP from electron transport chain
in the electron transport chain, how many ATP are produced per NADH? how many are produced by NADH total (for one reaction)
2.5 ATP/NADH
25 total for 10 NADH
in the electron transport chain, how many ATP are produced per FADH2? how many are produced by FADH2 total (for one reaction)
1.5 ATP/FDH2
3 total (for 2 FDH2)
what would happen if a proton (H+) channel was inserted into the inner mitochondrial membrane?
-less ATP would be made for same amount of glucose
-more energy would be lost as heat
Why does FADH2 produce less ATP than NADH?
Because it enters at an energy level inferior to the energy level that NADH enters (complex II instead of complex I), so it releases less energy and pumps less H+ across the membrane
what is the process of uncoupling?
-when chemiosmosis is uncoupled from ATP synthesis
-example: adding an additional proton channel into the mitochondrial membrane (not ATP synthase)
what are other organic molecules, from which cellular respiration can extract energy from?
proteins and fats
if proteins are used for cellular respiration, they are broken down to form amino acids in order to form what (to enter the cycle)?
-pyruvate
-acetyl-coa
-intermediates of the citric acid cycle
when proteins are broken down into cellular respiration components. what is released?
NH3
If fats are used for cellular respiration, what do they enter the cycle as?
glycerol: G3P
fatty acids: acetyl-coa
by what process do fatty acids become Acetyl-coa?
b oxidation
what are fats composed of?
1 glycerol and 3 fatty acids
what is cellular respiration regulation based on?
to respond to metabolic needs
what are the allosteric regulators of phosphofruktokinase?
ATP, AMP and citrate
which reaction does PFK catalyze?
3rd reaction of glycolysis
what are the allosteric inhibitors of PFK (phosphofruktokinase)?
-ATP
-citrate
what is the allosteric activator of PFK?
AMP
what is fermentation?
-production of ATP by glycolysis only (no ETC so no O2 needed)
how many ATP are produced through fermentation?
2 ATP/glucose
what is the extra step that fermentation takes?
-recycles NAD+ from NADH so glycolysis can continue
what are the 2 types of fermentation?
-alcohol fermentation
-lactic acid fermentation
What is the reaction for lactic acid fermentation?
what is being reduced during alcohol fermentation? why?
acetaldehyde. because NADH carries its electrons to acetaldehyde.
what is being reduced during lactic acid fermentation? why?
-pyruvate, because NADH brings its electrons to it.
during alcohol fermentation, what is acetaldehyde being reduced to?
ethanol
