Download Electron Transport Chain (1)

The stage in between that connects the glycolysis to the Kreb cycle is by using
oxygen.
We need other proteins to connect with each other because electrons can’t pass
through the cell membrane by itself.
Free-energy change during electron transport:
- Loses 2 electrons from breaking down NADH -> NAD+ (oxidizing)
- The protein complex includes the pump and a protein that breaks NADH
- The electrons travel through the protein
- Though, as the electrons travel through, it loses energy, so it is
swapped/recharged/replaced/exchange by other 2 excited electrons
from the breaking down of FADH2 -> FAD (the tired electron goes into
FADH2)
- The electron hydrogen gives energy to the protein complex and pumps
the H+
- Oxidized FADH2, gives out electron, the energy from excited electron
pushes hydrogen into the cristae
- The big purple proteins that are connected are multiprotein complexes
- When the electron finishes the journey at the last protein complex, the 2
electrons from NADH or FADH2 comes out, combining 2H+ (+) ½ O2,
which makes water or H2O
- That makes high concentration of H+ in the cristae
- That makes low concentration of H+ in the matrix
- Since there’s a higher concentration in the cristae, it wants to come in
- The only way to come in, it goes through the ATP synthase which makes
ATP by ADP + P
Every molecule of glucose, potentially we make about 38 ATP. Without oxygen,
you can’t do the link stage, kreb cycle, etc.
ATP Synthase, a molecular mill:
- ATP synthase = the enzyme that actually makes ATP from ADP and
inorganic phosphate.
- H+ ions are flowing down their gradient, entering a stator, which is
anchored in the membrane
- H+ ions enter binding sites within a rotor, changing the shape of each
subunit so that the rotor spins within the membrane
- Each H+ ion makes one complete turn, leaving the rotor and passing
through a second half channel in the stator into the mitochondrial matrix
- Spinning of the rotor causes an internal rod to spin as well. This rod
extends like a stalk into the knob below it, which is held stationary by
part of the stator
- Turning of the rod activates catalytic sites in the knob that produce ATP
from ADP and P.
The electron transport chain:
It happens in the inner membrane of the mitochondria where we have a series of
proteins (cytochromes). We’re going to release energy from the energized
electrons.
-
Break NADH (loses electron) -> NAD+
The energy from the electron pushes the H+ into the cristae (inner
membrane)
Then, the electron (non-energized) is swapped with the electron that is
broken down from the FADH2 to make FAD.
The energy from the electron pushes the H+ (2 H) into the cristae (inner
membrane)
Then, the electron moves across the protein, and the 2H+ combines with
oxygen to make water or H2O.
The energy left from making H2O pushes the H+ into the inner membrane
or the cristae.
Since, the concentration in the inner membrane is so high (H+), it’s trying
to push its way through the ATP synthase. The energy from pushing
makes ADP + P = ATP. (oxidative phosphorylation)
Alcohol fermentation:
- They pull out carbon dioxide
- By doing that, it turns a 3 carbon pyruvate into 2 carbon pyruvate
- Reduce the 2NAD+ -> 2NADH
- Those 2NADH would go through ____ to make 2ATP by 2ADP + 2P
Catabolism:
- Fats are broken down by beta-oxidation and they can be broken down
into glyceraldehyde-3-phosphate or acetyl CoA
- Carbohydrates: break down the glycosidiclinkages and we get sugars
which goes straight into glycolysis
- Proteins: becomes amino acids and can be turned into pyruvate, acetyl
CoA or it can go straight into the citric acid cycle
- Then everything that goes to the citric acid cycle, continues to go to the
oxidative phosphorylation
Control of cellular respiration:
- Starts with glucose
- Gets into glycolysis fructose-6-phosphate
- The third enzyme (phosphofructokinase) is being stopped by the inhibits
(citrate) or the other inhibitor by ATP
- Once there’s AMP (bad situation), then the body stimulates
phosphofructokinase
Beta Oxidation – the way fats are broken down
What’s the difference between alcohol fermentation?
How do we do lactic acid fermentation?
Can you explain how proteins give out NH3?
How does AMP stimulate the phosphofructokinase?
Can you explain why citrate is in the diagram?
Self-Quiz:
1) B = NADH
2) D = H+ concentration across the membrane holding ATP synthase
3) C
4) C
5) A
6) A
7) D
8) B
9) B
10) The line goes up
11) Endosymbiosis. By comparing the ATP synthase in our cell membrane
and prokaryotes then its similar, they’re the same because they came
from the same place
12) We won’t get any membrane potential and we won’t get ATP
13) They left food, and then got drunk. The alcohol kills bacteria.
Photosynthesis experiment: bring a very dark green leaf/vegetable
We’re looking at different pigments of leaves (chromatography). What colors are
absorbed in the sth spectrum.