Photosynthesis Flashcards
Why engineer photosynthesis
Growing world population, more mouths to feed
Climate change (caused by increased CO2 in air) increases environmental stresses, limiting crop production. Assimilation (CO2 taken in by plant) increases but so does respiration (energy/sugar burning) so net obtained through photosynthesis is 0
Ex. Area coffee is grown in Asia will be unsuitable in next 20 years
Photosynthesis
Stomata allows gas exchange (CO2 in, O2 out)
Below are spongy mesophyll, area for gas to travel through
Photosynthesis occurs in chlorophyll in chloroplasts, light reactions in thylakoid (light energy, water, ADP, P produces ATP, NADH and O2//), dark reactions of Calvin-Benson-Basham in which sugars are produced
Types of plants
C3
Intermediates have 3 carbons
6C glucose into…
C4
Additional step in which C4 intermediate made that’s not a gas so pumped into bundle sheath cells
C4 is split to evolve CO2 and fed back into cycle
Ex. maize, sugarcane, millet, etc
CAM
C4 intermediate is made but instead of bundle sheath cells, is used in day
Stomata opens at night which is cooler allowing less water loss in gas exchange
Ex. pineapple
Method to engineer photosynthesis
Engineer C3 plants to be C4 since it has happened multiple times in evolution so chemically possible
Began with rice. Initially transferred 5 genes but later realised 16 were needed
The 5 genes were successfully transferred but didn’t function as required.
Needed cell to favour our process over the plants
Ways to promote photosynthesis
Manipulate photosynthesis to increase the efficiency of energy conversion
Enhance tolerance of high light and temperature
Productively increase intra-chloroplast CO2 concentration
Maximise light harvesting
