Lecture 24: Photorespiration Flashcards
does CO2 or O2 produce higher catalytic activity with rubisco and how much more
100-fold higher catalytic activity of rubisco with CO2 over O2
when is O2 more soluble than Co2 in rubisco
In hot temperatures, as it is typically higher compared to CO2
T/f: elevated levels of O2 increase the rate of photosynthesis
f, it decreases it due to photorespiration
what 2 competing reactions does rubisco catalyze
carboxylase and oxygenase
what organelles does photorespiration occur in
chloroplast, peroxisome, and mitochondrion
where do peroxisomes tether to
chloroplast
glyoxysome
peroxisome in seed
peroxisome
single membrane organelle with no DNA or ribosomes
what does photorespiration produce that is on of reactive oxygen species
H2O2
what are important regulators of amino acid content in plants
GGAT and SGAT
overall reaction of photorespiration
2 glycine + NAD+ ——> Serine + CO2 + NH3
glycine decarboxylase complex
glycine cleavage system in mitochondria during photorespiration
how does the glycine decarboxylase complex work
1 glycine is decarboxylated, deaminated, and the central C of glycine is transferred to a one carbon carrier
serine hydroxymethyltransferase
1 carbon in the carrier is transferred to another glycine to produce serine
why and when does photorespiration occur
occurs in hot and dry weather
when concentration of CO2 inside leaf becomes low
increased atmospheric and leaf temp
when rubisco combines O2 rather than CO2 with RuBP
