Exam 3 Lecture 29 flash cards

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  1. Calvin cycle
    • 1. Carboxylation of and splitting: 6C → 2[3C]
    • - ribulose 1,5-bisphosphate (5C) condenses with
    • CO2 and H2O to form a 6C molecule and splits
    • into 2x3C (catalyzed by Rubisco)
    • 2. Reduction of 3C
    • molecule by NADPH
    • (ATP is used!)
    • - 6 cycles provide 2x3C
    • for making Glc
    • 3. Regeneration of
    • ribulose 1,5-bisphosphate
  2. carboxysomes.
    • The carboxysome takes up bicarbonate (HCO3
    • –), which
    • is then immediately converted to CO2 by carbonic
    • anhydrase.
    • The CO2 is then fixed by Rubisco.
  3. TCA cycle
    The tricarboxylic acid cycle (TCA cycle) is a series of enzyme-catalyzed chemical reactions that form a key part of aerobic respiration in cells. This cycle is also called the Krebs cycle and the citric acid cycle.
  4. reverse, TCA cycle
    • - Uses ATPs and NADPH (NADH) to fix CO2
    • - This allows building of acetyl-CoA and sugars
  5. The reductive acetyl-CoA pathway:
    • - Used by anaerobic soil bacteria, autotrophic
    • sulfate reducers, and methanogens
    • - Two CO2 molecules are condensed through
    • converging pathways to form the acetyl group of
    • acetyl-CoA.
    • - Reducing agent is H2! instead of NADPH.
  6. The 3-hydroxypropionate cycle:
    • - Used by thermophiles
    • - Acetyl-CoA condenses with hydrated CO2
    • (bicarbonate ion, HCO3
    • –) and is reduced by
    • 2 NADPH to 3-hydroxypropionate.
    • - In all, three molecules of CO2 are fixed into one
    • molecule of pyruvate, which serves as a
    • substrate for biosynthesis.
  7.  Nitrogen gas (N2) is fixed into ammonium ion (NH4
    +)
    only by some species of bacteria and archaea.
    • Aquatic cyanobacteria develop special cells called
    • heterocysts to fix N2. Photosynthesis is turned off to maintain
    • anaerobic conditions.
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Exam 3 Lecture 29 flash cards
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lecure 29 flash cards
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