Lecture 7 Bio 172.pptx - Biology 172 Lecture 7 Thursday...

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Lecture 7: Thursday, July 13, 2017 Biology 172 Today’s Outline Photosynthesis - Overview - Light Reactions Noncyclic photophosphorylation Cyclic photophosphorylation - Calvin Cycle Quiz 4 due Friday by midnight Extra office hours this and next week Thurs: 10:30-11:30, 2:00-4:00 In class review Monday, July 17 in 2260 USB Office hours 11-12, after review until 3:30 Tuesday 10-11:30 Chatroom Monday 8:00-9:00 pm EXAM TUESDAY, JULY 18 STARTS AT NOON!!! Announcements
Lecture Objectives Understand the reactions of photosynthesis. Know input and output of light reactions and Calvin cycle. Know where each occurs in prokaryotes and eukaryotes. Be able to trace the path of electrons as they move move through the Z scheme. Understand resonance and redox reactions and the difference between antenna pigments and the reaction centers Understand why a plant undergoes cyclic photo- phosphorylation and what is involved. Know the 3 phases of Calvin cycle Understand why rubisco is inefficient and what photorespiration is Understand the similarities between the mitochondria and the chloroplasts with respect to what is happening in each compartment
Photoautotrophs are photosynthetic organisms that make their own food from ions and simple molecules using the energy from the sun They are producers Photosynthesis The process of converting the energy in sunlight into chemical energy. Glucose
Plants Unicellular protist Multicellular algae Cyanobacteria Purple sulfur bacteria 10 µm 1.5 µm 40 µm Photoautotrophs: producers for most ecosystems
Use of sunlight by plants
Photosynthesis Glucose The process of converting light energy into chemical energy (organic molecules) Light Reactions: (Photo) Use the energy from sunlight to generate high energy molecules ATP and NADPH Calvin Cycle: (Synthesis) Uses the high energy molecules ATP and NADPH to reduce 6 CO 2 into 1 C 6 H 12 O 6 Anabolic process
Photosynthesis Light! Oxidation-Reduction (redox) Reactions coupled electron transfer reactions Oxidation – loss of electron(s) from one substance Reduction – gain of electron(s) by another substance Basically the reverse of cellular respiration
Photosynthesis occurs in chloroplasts (plants/algae) or plasma membrane and cytosol (some prokaryotes)
How is gas exchange accomplished in leaf cells? CO must diffuse into the cell for photosynthesis, while water is lost. This is accomplished by stomata (stomates),openings or pores in leaf epidermal cells. The size of the pores is regulated by a pair of specialized cells known as guard cells. 2

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