11.1 Chemiosmotic Theory Flashcards
how much ATP does one molecule of glucose yield?
32
describe the energy yield of glycolysis
net gain of 2 ATP produced in steps 7 and 10
describe the energy yield of the citric acid cycle
net gain of 2 GTP from step 5
where does most of the ATP produced from a molecule of glucose come from?
most comes from oxidative phosphorylation
what powers oxidative phosphorylation?
chemiosmosis
what is chemiosmosis?
protons move down a gradient to generate ATP
other than ATP, what do glycolysis and the citric acid cycle produce?
powerful reductant molecules
what kinds and how many reductants are produced from one molecule of glucose?
10 NADH
2 FADH2
what do the reductants from glycolysis and the citric acid cycle reduce?
reduced O2 to H2O
what do redox reactions power and what does this establish?
redox reaction power the pumping of protons and establish a gradient across the inner mitochondrial membrane that protons can move down to generate ATP in chemiosmosis
can protons penetrate the mitochondrial membranes alone?
nope
what does the inner membrane of the mitochondria contain? what is the purpose?
crista, or folds; increase surface area
what is embedded in the innermembrane of the mitochondria?
ATP synthase
what is the mitochondrial matrix? what happens there?
the aqueous interior of the mitochondria where the citrate cycle happens
describe the proton circuit
- redox reactions are coupled to electron transport
- redox reactions are used to pump protons across membrane, which establishes H+, chemical, and electrical gradients
- H+ passively flow through ATP synthase, which produces ATP
what are 3 names for the innermembrane side of the proton circuit?
- P side
- positive side
- acidic side
why is the innermembrane side of the proton circuit called the positive and acidic side?
has more H+ so more positive charge; and more H+ makes more acidic
what are 3 other names for the matrix side of the protein circuit?
- N side
- negative side
- basic side
why is the matrix side of the proton circuit also called the negative or basic side?
has fewer protons so more negative charge, and fewer H+ makes it more basic
what does the amount of mitochondria per cell depend on?
the energy needs of that cell
describe the relative amount of mitochondria of slow twitch muscles and why
slow twitch muscles need aerobic energy for long periods of time so have more mitochondria
describe the relative amount of mitochondria of fast twitch muscles and why
fast twitch muscles need aerobic energy in short bursts only so have fewer mitochondria
what do plants have that are analagous to mitochondria?
chloroplasts
what are the 4 differences between chloroplasts and mitochondria?
- in chloroplasts, ATP synthase sits in the thylakoid membrane, not an inner mitochondrial membrane
- light energy powers ATP synthase in chloroplasts, not redox energy
- the proton circuits in chloroplasts and mitochondria are flipped relative to each other
- choloroplasts use photosystems I and II, not the ETC that mitochondria use
what is the function of the proton circuit?
an electrical circuit that converts potential energy into work
what creates the H+ gradient in the proton circuit?
the electron transport system
what does the H+ gradient of the proton circuit do?
stores potential energy generated by the electron transport system
what role does ATP synthase play in the proton circuit?
is the motor that performs the work
due to the H+ gradient in the proton circuit, what happens?
chemiosmosis; protons flow in one direction throught ATP synthase due to charge
what are the 2 ways to disrupt the proton circuit?
- uncouplers
- inhibitors
what do uncouplers do to the proton circuit?
allow the proton circuit to continue, but not through ATP synthase; instead divert flow through an alternate route
what do inhibitors do to the proton circuit?
block the proton circuit and stop proton flow all together
what kind of proteins are uncoupling proteins and what do they do?
thermogenin proteins’ uncouple oxidative phosphorylation
how do thermogenin proteins work to uncouple oxidative phosphorylation? (3)
- divert H+ flow away from ATP synthase
- allow H+ to flow without ATP synthesis
- energy is converted to heat instead
give an example of a thermogenin protein that uncouples oxidative phosphorylation
2,4-dinitrophenol
what is 2,4-dinitrophenol? (2)
- a popular anti-obesity drug in the 1930s
- shifts the proton electrochemical gradient so potential energy dissipates as heat instead of being converted to ATP
list 2 effects and the side effects of 2,4-dinitrophenol
- heightened metabolic rate and increased fat metabolism
- leads to an accumulation of pyruvate and lactic acids
- hyperthermia, hepatotoxicity, formation of cataracts, agranulocytosis
sum up the mechanism of 2,4-dinitrophenol
is protonated in the low pH of the mitocondrial intermembrane space, then crosses into the matrix and deprotonates in the high pH of the matrix, basically shoving a proton across the membrane and fucking up the gradient
what is oligomycin?
an antibiotic that blocks ATP synthase, blocking the proton circuit
what is the result of oligomycin stopping the proton flow back into the matrix via inhibiting ATP synthase?
- buildup of H+ in intermembrane space results in very low pH
- lack of H+ in matrix means the matrix has a very high pH
- no ATP production
- cell death
