ATP-ETS Flashcards
3 types of catabolic reactions in cellular respiration
Nutrient catabolism
Citrate cycle
Ox phos
Net energy gain in glycolysis
2 ATP
2 NADH
For every glucose
Net energy gain in B oxidation
1 FADH2
1 NADH
for every 2 C
Net energy gain in citrate cycle
1 FADH2
3 NADH
1 ATP
for every turn of the cycle
Net ATP in the ETS-Ox phos
1 NADH = 2.5 ATP
1 FADH2 = 1.5 ATP
B oxidation
- Remove 2 C units as acetyl CoA
- Acetyl CoA enters CC
- Resulting NADH and FADH2 enter the ETS
Major molecules of CC
Citrate, isocitrate, aKG, succinyl CoA, succinate, fumarate, malate, oxaloacetate
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Metabolic fuels that can enter the CC
AA, glucose, ketones, fatty acids
Do AA have to be turned in to acetyl CoA before entering the cycle?
No, they can enter at different points in the cycle, but they can turn into acetyl CoA if they want.
Irreversible reactions in the CC
Citrate synthase - no regulators indirect effector (high [NADH] = lowers [OAA and acetyl CoA]
Isocitrate DH - inhibitors - ATP and NADH
aKGDH - inhibitors - ATP/GTP, NADH
What reactions produce NADH?
Isocitrate DH, aKGDH, malate DH
Electron transport system
Transfer e- by NADH or FADH2 to reduce O2 to H2O
= proton gradient
Ox phos
Generation of ATP by ATP synthase with proton gradient from ETS
Where does ox phos occur?
IMM
Complex I
NADH DH and proton pump
NADH donates hydride ions for proton pumping
CoQ binds complex I and accepts e- donated by NADH hydride
CoQ
Non protein
Can do redox reactions and acts as a shuttle between I (and II) to complex III
Lipid soluble, can diffuse easily through membrane
= 4 H+
Complex II
Transport e- from FADH2 from CC to CoQ
Not proton pump
Succinate DH
Complex III
Reduce heme iron from Fe3+ to Fe2+
E- from CoQ drive proton pumping
= 2 H+
CytC
Transports e- from complex III to IV
Cellular respiration
The set of metabolic reactions and processes in a cell to convert nutrients into ATP and waste products
Complex IV
Cytochrome oxidase
accepts e- from CytC
Iron and copper complex
Reduces O2 to H2O for proton pumping
4 H+
ATP synthase F0 subunit
Membrane bound
C subunit - protein rotor, protons enter after 1 turn of motor
A subunit - non rotating channel, protons pass through to enter matrix
Gamma subunit - rotating protein (driven by c subu)
ATP synthase F1 subunit
In the matrix
3 pairs of alpha/beta subunits that bind ADP and Pi to make ATP
How does the ATP synthase work?
- Proton passes through the alpha subu into the c subu.
- Protons binds to c subu causing it to rotate
- The next c subu releases proton in the matrix and rotates into position next to the a subu
- All three steps happen 3 times, so the rotor will move 120 degrees. Each 120 rotation, the gamma subu will contact a new pair of alpha/betas in the F1 catalyzing ATP formation
How many protons make 1 molecule of ATP in the ATP synthase?
4 H+ = 1 ATP
Final electron acceptor in ox phos?
O2 accepts e- and is reduced to H2O
Adenine nucleotide translocase
IMM transmembrane protein
Transports ATP out of matrix
Transports ADP into matrix
Voltage dependent anion channel
OMM transmembrane protein
Transports anions and ATP for intermemb space to cytoplasm
Transports ADP from cytoplasm into intermemb space
Malate aspartate shuttle
- NADH is converted to NAD+ by reducing OAA to malate
- Malate is shuttled into the matrix
- Malate oxidizes to OAA converting mitochondrial NAD+ to NADH
- Mito NADH donates e- at complex I
- OAA is converted to aspartate to prevent buildup of OAA in matrix
- Aspartate exists via aspartate transporter
- In cytosine, aspartate is converted back into OAA completing cycle
How do you get NADH in the matrix from cytosol?
Malate-aspartate shuttle
G3P shuttle
G3P shuttle
- NADH is converted into NAD+ in cytosol from DHAP to G3P reaction
- G3P is re oxidized by mito G3PDH (bound outside IMM)
- This reduced FAD to FADH2
- Mito G3PDH acts like complex II transferring FADH2 e- to CoQ
