Lecture Cycle 4

• Where does the calvin cycle occur?

  stroma of chloroplast
• What are two phases of photosynthesis?

  light dependent reactions and the calvin cycle
• How does a photosystem work? How do the different parts work together? ....
• Why is there so little photosynthesis in the ocean?

  lack of nutrients, especially iron
• What is the definition of photosynthesis?

  light dependent reduction of CO2 to carbohydrate (glucose)
• What type of reaction is occurring in photosynthesis (energy and reaction)?

  -redox reaction

  -endergonic (lowering energy)
• What is oxidized and what is reduced in photosynthesis?

  -oxidized: glucose

  -reduced:CO2
• What is bacteriorhodopsin? What does it do?

  light driven pump that created a proton gradient that produces ATP
• Where is bacteriorhodopsin found?

  halophilic archaea
• What types of organisms have bacteriorhodopsin?

  heterotrophs
• What are the key structures of a chloroplast?

  stroma, lumen, thylakoid, genome
• What happens in the stroma? What is there?

  the calvin cycle, contains lots of enzymes
• What is in the thylakoid?


  the site of photosynthesis
• What is the protein that is only encoded for in the chloroplast genome?

  D1
• What is the point of the electron transport chain?

  create a proton gradient that results in the creation of ATP
• What is the pathway of the electron transport chain?

  H2O, PSII, PSI, NADPH + ATP, Calvin cycle
• What does ATP synthase do?

  catalyses ATP synthesis
• How does redox potential explain electron flow?

  the increase in electron affinity across the chain explains how the electron flows because each acceptor has greater affinity than the prior one
• How does the redox potential of chlorophyll change upon photon absorption?

  redox potential becomes more negative (easier to oxidize)
• Why are photosystems essential?

  functional units for photosynthesis
• What is the pathway of P680? How do the stages convert? What happens at each stage of the chlorophyll?

  p680 gains a proton, p680* is easily oxidized, electron leaves resulting in p680+ which is very reactive, p680+ oxidizes H2O resulting in an electron being released that goes back to p680
• Why would chlamy be negatively phototactic?

  light can be damaging
• What is the cycle that PSII undergoes?

  PSII, exposure to light, damaged PSII, damaged D1 removed, inactive PSII, new D1 added, restored
• How does P680+ affect D1?

  electrons from H2O is not enough, so p680+ will steal an electron from D1
• How would a lack of water affect PSII?

  not enough electrons for p680+, would steal from D1 resulting in the rate of damage being greater than rate of repair; no fixing of CO2, no elctron transfer, no oxidation of H2O or reduction of CO2
• What is constantly happening to PSII? What needs to happen because of that?

  damage, needs to be constantly repaired
• What is lincomycin? How might it be used?

  antibiotic, blocks blocks ability to make D1, treat serious bacterial infections
• What would occur under high light to the D1 protein?

  rate of damge is greater than rate of repair
• What is the role of chloroplast protein synthesis in the repair cycle?

  D1 turnover
• What are the three phases of the calvin cycle and what happens in each?

  1. fixation: rubisco fixes CO2 to RuBP producing 3-PGA

  2. reduction: ATP and NADPH are used to convert 3-PGA into G3P

  3. regeneration: G3P that doesn't leave to make glucose is recycled to regenrate RuBP
• Why did the Calvin cycle evolve? What is its purpose?

  to turn CO2 from air into sugar which is needed for food for autotrophs to grow
• What is the location and purpose of glycolysis?

  -cytosol

  -oxidation of glucose to generate pyruvate (some ATP and NADH are sythesized)
• What is the location and purpose of citric acid cycle?

  -mitochondria

  -oxidize pyruvate to make acetyl-CoA
• What is Rubisco?

  Enzyme that catalyzes the fixation of CO2 with RuBP.
• What is RuBP?

  5 carbon sugar that accepts CO2
• What is PGA?

  intermediate of the calvin cycle
• What is G3P?

  intermediate of glycolysis that is the carbon backbone for biosynthetic reactions
• What is substrate-level phosphorylation?

  direct transfer of a phosphate to ADP generatinf ATP
• What is the relative free energy of intermediate compounds (glucose vs. pyruvate vs. CO2...etc)?

  -pyruvate has less free energy than glucose

  -pyruvate reduced be NADH
• What is the process of anoxygenic respiration? light requirements?

  light is used to raise electron to more negative redox potential, resulting in the production of ATP without oxygen