Seminar 9: How do organisms generate energy from organic molecules I? Flashcards
cellular resp eqn
C6H12O6 > 6CO2 + 6H2O + 36ATP
what type of reaction is cellular resp & why?
exergonic (ATP released)
what are the 4 steps of cellular resp & where do they occur?
- glycolysis - cytosol
- Pyruvate oxidation - mitochondrial matrix (cytoplasm for prokary)
- Citric Acid cycle - mitochondrial matrix
- Oxidative phosphorylation (ETC & chemiosmosis) - mitochondrial membrane
how does glycolysis prod energy & how much is prod?
- glucose (6 C) is oxidised into 2 pyruvate (3 C)
- C-H bonds oxidised (lose e-) releases energy
4 ATP prod BUT 2 ATP USED (in 1st stage), NET = 2 ATP (overall EXERGONIC)
desc the 1st half of glycolysis (steps 1-5)
- endergonic part (requires 2 ATP)
STEP 3: main step of glycolysis regulation - phosphofructokinasecatalyses phosphorylation of fructose 6-phosphate > fructose 1,6-biphosphate - ATP inhibits enzyme when ATP conc HIGH, glycolysis, TCA cycle, ETC slowed down so ATP prod decreases
- ADP/AMP activate the enzyme
desc the 2nd half of glycolysis (steps 6-10)
- exergonic part
- yields 4 ATP & 2 NADH
how is energy generated when O2 is absent?
undergo fermentation or anaerobic respiration
fermentation in animals
- lactic acid prod
- reversible
- lactate build up decreases pH/^acidity, changes environ of cell, affects cellular func & causes muscle pain/cramps
- prod NAD+ (NADH is regenerated for the 1st step in reaction)
- NADH is a cofactor for GADPH enzyme so glycolysis can occur w/o O2
fermentation in yeast
- prod 2 ethanol, 2 ATP, 2 CO2
- reversible
- NAD+ is byproduct, recycled back so ATP can be prod (via reduction from ADP + Pi > ATP)
define fermentation
incomplete oxidation in absence of O2, produces energy w/o ETC & oxidative phosphorylation
GLYCOLYSIS STILL OCCURS
define anaerobic respiration
cellular resp w/o O2, still contains ETC & oxidative phosphorylation
- occurs in many bacteria
- prod of CO2 may be absent
- final e- acceptor in ETC NOT O2 (sulfur, iron)
