Photosynthesis – Lesson 3 Plant Types

Review In the chemiosmotic synthesis of ATP, H+ diffuses through ATP synthase from the _____ to the _____ (a)Stroma to the thylakoid (b)Thylakoid to the Stroma

Review Rubisco: (a)Reduces CO 2 to G3P (b)Adds CO 2 to RuBP during carbon fixation Cyclic electron flow in the chloroplast results in the production of: (a)ATP (c) Oxygen (b)NADPH(d) None of the above

Compare and Contrast: Versus:

C3 Plants Cool, moist environments Examples:

C3 Plants Called “C3” because the 1 st organic product of the Calvin Cycle is a 3-carbon mol. (3- phosphoglycerate) When [CO 2 ] is low, rubisco takes in O 2. This is called “photorespiration” and does not produce ATP or NADPH RuBP + O 2 → Phosphoglycolate + 3- phosphoglycerate Why would a C3 plant do this?

Photorespiration

C4 Plants Hot, dry environments Examples:

C4 Plants First product after carbon fixation gives a 4- carbon compound (oxaloacetate) Has unique leaf anatomy with 2 kinds of photosynthetic cells: (1) Bundle Sheath Cells and (2) Mesophyll Cells Mesophyll cells take in CO 2, but Calvin Cycle occurs within Bundle Sheath only

C4 Plants

CAM Plants Hot, dry, arid environments Examples:

CAM Plants Crassulacean Acid Metabolism Open stoma during night and close during day (why?) CO 2 is incorporated into organic acids at night Mesophyll cells of CAM plants store organic acids they make at night in their vacuoles until morning

Homework Read Section 3.4 in your text (pages ) Finish cheat sheet for Light Reactions and Calvin Cycle Start your cheat sheet for C4 and CAM plants only (not C3) Plant Chromatography Lab: postponed until next week

Tomorrow: You will have a review period to work on the following: Cheat sheets Readings for lab Catching up on missed homework Reviewing photosynthesis lessons (1 – 3) in preparation for a quiz next week (exact day of quiz TBA)