Krebs Cycle, Oxidative Phosphorylation Flashcards
pH layers of the mitochondria
pH of mitochondrial matrix (9) > pH of cytosol (8) > pH of the intermembrane space (5)
superoxide dismutase
an enzyme used to neutralize oxygen radicals, used by the body to induce cell death and destroy invading pathogens
reactive oxygen species
a common cause of apoptosis and cellular damage
1 molecules of acetyl CoA yields…
1 ATP, 3 NADH, 1 FADH2
= 10 ATP total
protons per NADH, FADH2
10 protons per NADH, 6 protons per FADH2 (1 ATP per 4 protons)
these are electron shuttles
steps of aerobic CR
- Glycolysis
- Pyruvate oxidation
- Krebs cycle
- Electron transport chain
(the complete degradation of glucose)
purpose of the citric acid cycle (Krebs cycle)
- to reduce NAD+ and FAD
reactants: CoA, pyruvate
products: NADH, ATP, acetyl CoA
ATP synthase
pumps hydrogen ions into the intermembrane space during electron transport chain
ATP per NADH, FADH2
2-3 ATP per NADH, 1-2 per FADH2
Electron Transport Chain (reactants, products)
reactants: ADP, oxygen, NADH
products: ATP, NAD+
inorganic phosphate
exists in the mitochondrial matrix, which decreases as ATP synthase produces ATP
proton pumps
complex IV and III are proton pumps, so they change the pH of the intermembrane space. complex II does not change the pH
glucose oxidation (3 steps)
- glycolysis
- citric acid cycle
- oxidative phosphorylation
CR final electron acceptors
NADH, FADH2
NADPH is used in photosynthesis
where is water formed?
in the mitochondrial matrix
? water continues to be formed if the membrane is permeable to hydrogen protons
chemiosmosis
moves hydrogen protons into the mitochondrial matrix, while electron transport chain pumps protons into the intermembrane space
oxygen
the final electron acceptor, CN interferes with complex IV so oxygen will not be reduced
where does glycolysis occur?
cytosol.
- produces 2 pyruvate (3-carbon), which is broken down into a 2-carbon molecule called Acetyl CoA. one carbon leaves to produce CO2
- produces a net of 2 ATP (generates 4 and uses 2) and 2 NADH
citric acid cycle
starts with acetyl CoA (processed glucose), which is broken down to form intermediates useful for OP
oxidative phosphorylation
occurs AFTER citric acid cycle; leads to the formation of ATP
oxaloacetate
the intermediate of the citric acid cycle, which combines with Acetyl CoA to form citric acid (citrate; 6-carbon) which is oxidized back to oxaloacetate after releasing two CO2 molecules
products of CAC
- GTP (from GDP)
- 3 NADH and 1 NADH from pyruvate oxidation, and 1 NADH from glycolysis
- 1 FADH
- 2 CO2
- regenerated oxaloacetate
(6. 1 ATP)
“prep step” for Krebs
think of it as pyruvate oxidation:
pyruvate is converted into Acetyl CoA via pyruvate dehydrogenase, with a reduction of one NAD+ to NADH, and 1 CO2 is released
an irreversible step
allosteric activators/inhibitors of CAC
activators: ADP, CoA, NAD+, pyruvate, AMP, Ca2+
inhibitors: acetyl CoA, NADH, ATP, fatty acids
free calcium is produced when muscles are using energy
if we have enough fatty acids, it’s a signal we can slow this process down
- there is no hormonal control of this cycle
fatty acids can/can’t be converted into acetyl CoA
can. but because pyruvate dehydrogenation is irreversible, fatty acids cannot be converted into glucose because this step is irreversible
OIL RIG
oxidation is losing electrons, reduction is gaining electrons
where does CAC take place?
inside the mitochondrial matrix
total ATP produced from 1 molecule of glucose
~30-32 ATP
describe the electron transport chain
complex I takes electrons from NADH while complex II takes electrons from FADH2
NADH is #1, FADH2 is #2
electrons are sent to Ubiquinone, or Q, which are sent to complex III, then Cytochrome C, then complex IV, then oxygen is the final electron acceptor
this “pumps” hydrogens into the inner membrane space
the major substrate activator of ETC
ADP!
what happens in apoptosis
the permeability of the mitochondria increases, and Cytochrome C leaks out
CR totals (write out by memory!)
glycolysis: 2 ATP, 2 NADH
pyruvate oxidation: 2 NADH
krebs/CAC: 2 ATP, 6 NADH, 2 FADH2
