Photosynthesis Part Deux

Recap The point of PS is to make sugar The Light Reactions: Linear electron flow- uses an ETC Photosystems II and I with pigments absorb light Photons excite electrons in photosystems Energy used to pump out protons Proton motive force used to make ATP, pumped into stroma Electrons captured by NADP+ Water is split and oxygen is released Cyclic electron flow uses PSI only- makes ATP

Quick Practice ? grana ? thylakoid ? stroma ? O2

The energy molecules produced in the Light Reactions are used to power the synthesis of carbohydrates in the Calvin cycle. NADPH ATP CO2 C6H12O6

The Calvin Cycle occurs in the stroma of the chloroplast.

IN SUM: The three parts of the Krebs Cycle are: Carbon dioxide fixation, carbon dioxide reduction, and regeneration of RuBP. NADPH ATP CO2 C6H12O6

Rubisco is the most abundant enzyme in the world Rubisco is the most abundant enzyme in the world. It takes CO2 out of the air and fixes it in organic compounds, making it available to life. (carbon fixation) Enzymes are what kind of biomolecule? What is the monomer of that biomolecule? What are R-groups? What is an active site? What is a substrate? What does an enzyme do to activation energy? What are the four levels of protein structure?

The Calvin Cycle creates G3P, a 3-C sugar The Calvin Cycle creates G3P, a 3-C sugar. PGAL and G3P are the same thing. The cycle must occur twice for one glucose (6-C sugar) to be produced. Calvin Cycle Animation

G3P can be converted into other things too. Figure 7.9

Find out more! Photosynthesis first evolved in prokaryotic organisms. Scientific evidence supports that prokaryotic (bacterial) photosynthesis was responsible or the production of an oxygenated atmosphere. Prokaryotic photosynthesis pathways were the foundation of eukaryotic photosynthesis.

Remember that both CR & PS are enzyme-mediated. What would you expect to happen to the rate of both if…and why? Heat is slightly increased? Heat is extremely increased? Heat decreases and it becomes cold? pH decreases or increases drastically? Salinity increases or decreases drastically?