Occur during the calvin cycle cycle must occur 3x to

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: • Series of steps which utilize ATP to rearrange 5 molecules of G3P to regenerate 3 molecules of RuBP release of oxygen does not occur during the calvin cycle • Cycle must occur _3x to produce 1 __ net G3P (Fixing 3 CO2) Possibly the most abundant protein on Earth – Technically produces 6 G3P molecules but 5 must be used to regenerate RuBP • For 1 G3P, cycle uses 9 ATP and 6 NADPH 7 1/3/2013 Trouble with Rubisco O2 Rubisco • _______ can fix ___ in place of CO2 – O2 added to Calvin Cycle instead of CO2 creating a 2-carbon compound that is broken down by mitochondria and peroxisomes to release CO2 – Consumes ATP and decreases photosynthesis by siphoning off material from the Calvin Cycle Photorespiration decreases efficiency of the plant • Problem in hot dry climates – Plants close stomata to minimize H2O loss but this reduces the amount of CO2 available – Concentration of O2 released from light reactions increases favoring O2 fixation -- rate of photorespiration will increase which is not good for the plant 8 1/3/2013 Alternative Mechanisms for CO2 Fixation • Plants that use rubisco for initial carbon fixation are called C3 plants – Because first product formed is 3-carbon compound • Some plants have alternative modes of carbon fixation to minimize photorespiration – C4 Plants – CAM (crassulacean acid metabolism) C4 Plants • Carbon fixation is separated _SPATIALLY ________ from the Calvin cycle – CO2 is initially fixed by PEP carboxylase _____________ in mesophyll cells to form a 4-carbon product – Product is transported into bundle sheath cells where the CO2 is released and...
View Full Document

This note was uploaded on 01/14/2014 for the course BIO 1113 taught by Professor Rothacker during the Winter '12 term at Ohio State.

Ask a homework question - tutors are online