BSC-2010 Lecture Notes - Lecture 2: Ethanol Fermentation, Cellular Respiration, Light-Dependent Reactions

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24 Oct 2016
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Fermentation
glycolysis forms pyruvate but there is insufficient oxygen
ethanol or lactate
anaerobic metabolism: fermentation
fermentation by facultative anaerobes (yeast)
glycolysis forms NADH and some ATP, stops if theres insufficient NAD+
NAD+ has to be regenerated by NADH [oxidizing] for glycolysis to continue
creates ethanol - alcoholic fermentation
2 molecules of radioactive alcohol are formed from each molecule of glucose
fermentation in muscle
creates lactate - lactic acid fermentation
Connections to other metabolic pathways
G3P (glyceraldehyde 3-P)
carbs: sugars —> glycolysis (glucose -> G3P -> Pyruvate) —> Acetyl CoA —> citric acid
cycle —> oxidative phosphorylation
proteins: amino acids —> pyruvate [releases ammonia]/ acetyl CoA/ citric acid —> oxidative
phosphorylation
fats: glycerol —> G3P —> pyruvate —> acetyl CoA —> citric acid cycle —> oxidative
phosphorylation
or fatty acids —> acetyl CoA —. citric acid cycle —> oxidative phosphorylation
control of cellular respiration: inhibition by negative feedback
PFK (phosphofructokinase) is an allosteric enzyme
glucose —> glycolysis (fructose 6-phosphate -> PFK -> fructose 1,6-biphosphate ->
pyruvate) —> acetyl CoA —> critic acid cycle —> oxidative phosph
citric acid creates ATP & citrate, both inhibit PFK
AMP stimulates PFK
Photosynthesis
6CO2 + 6H2O + hv —> C6H12O6 + 6O2 [byproduct]
hv = energy from sunlight
autotrophs & heterotrophs
photoautotrophs can be unicellular or multicellular, eukaryotic or prokaryotic
ATP made in chloroplast stays in chloroplasts
ATP that’s used by plant cell made by mitochondria through oxidative phosph
thylakoid disks: light reactions
synthesize ATP
store NADPH [high energy electrons]
produce O2 as a byproduct
calvin cycle: in stroma
convert CO2 to make CH2O (sugar)
breaks ATP into ADP+ and NADPH into NADP+
all wavelengths of light absorbed by granum in chloroplasts except for green
when electrons move from an outer shell to an inner shell, light is emitted
when light absorbed, electrons move up to an outer shell
photosystem in membrane of thylakoid disk
pigment molecules - absorb light
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generates high-energy electrons
light reactions & chemiosmosis decrease pH of thylakoid space
chemiosmosis in mitochondria & chloroplasts similarities:
electron transport chains that generate electrochemical gradients
low pH in intermembrane/thylakoid space
high pH in matrix/stroma
ATP synthase molecules that use electrochemical gradient to synthesize ATP
more membrane surface are = more ETC & ATP synthase molecules
calvin cycle
carbon fixation phase
anabolic - ATP & NADPH are used
CO2 input from atmosphere
rubisco [enzyme] initially fixates CO2
reduction phase
produces G3P
output - one molecule of G3P
regeneration phase
regeneration of RuBP
remaining G3P converted into carbon molecules by ATP
more ATP (9) used than NADPH (6)
cyclic electron flow
ATP produced by chemiosmosis
no production of NADPH or O2
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