BI110 Lecture Notes - Lecture 23: Pyruvic Acid, Vascular Bundle, Malic Acid
Document Summary
Different types of photosynthesis that occur in plants (already have talked about c3 photosythesis) Happens in first step of calvin cycle (carboxylation reaction represents the gain of carbon) Takes rubp a+co2 and splits them into two 3pga molecules. Rubp-o2 and splits them into one 3pga and one phosphoglycolate. Rubisco can use rubp with co2 or o2. O2 acts as a competitive inhibitor of rubisco (competing with co2 to bind to the binding site of rubisco) Ancient enzyme, developed when very little o2 in the atmosphere. Rubisco active site has greater affinity for co2 than o2 (will use co2 more than o2) Atmosphere is 21% o2 and 0. 04% co2 (more availability to bind to o2 but wants to use co2 more) Plant species have evolved mechanisms to reduce the oxygenation reaction. Increase ratio of co2/o2 (aka more co2) where calvin cycle (rubisco) takes place (so that the carboxylation reacton takes place more than the oxygenation reaction)
