🔬general biology i review

key term - NADPH

Definition

NADPH (nicotinamide adenine dinucleotide phosphate) is a crucial coenzyme involved in various metabolic processes, primarily acting as a reducing agent in anabolic reactions. It plays a significant role in photosynthesis by providing the necessary reducing power for converting carbon dioxide into glucose, linking energy conversion and biosynthesis.

5 Must Know Facts For Your Next Test

  1. NADPH is generated in the light-dependent reactions of photosynthesis, specifically through the actions of photosystem I.
  2. It serves as a key electron donor during the Calvin Cycle, helping to reduce 3-phosphoglycerate to glyceraldehyde-3-phosphate.
  3. The balance between NADPH and its oxidized form, NADP+, is essential for maintaining efficient photosynthesis and overall plant metabolism.
  4. In addition to photosynthesis, NADPH is important for cellular processes like fatty acid synthesis and detoxification of reactive oxygen species.
  5. The ratio of NADPH to NADP+ influences various metabolic pathways, as it helps regulate cellular redox states and energy balance.

Review Questions

  • How does NADPH contribute to the process of converting carbon dioxide into glucose during photosynthesis?
    • NADPH provides the necessary reducing power for the Calvin Cycle, where carbon dioxide is converted into glucose. During this process, NADPH donates electrons to 3-phosphoglycerate, facilitating its reduction to glyceraldehyde-3-phosphate. This conversion is essential for synthesizing carbohydrates that serve as energy sources for the plant.
  • Evaluate the role of NADPH in linking light-dependent and light-independent reactions in photosynthesis.
    • NADPH acts as a crucial intermediary between the light-dependent reactions and the Calvin Cycle. Produced during the light-dependent phase when light energy excites electrons in photosystem I, NADPH is then utilized in the Calvin Cycle to reduce carbon compounds. This connection underscores its importance not only as a reducing agent but also in maintaining energy flow within the overall photosynthetic process.
  • Assess how changes in NADPH levels could impact plant health and growth, especially under environmental stress conditions.
    • Changes in NADPH levels can significantly affect plant health and growth, particularly under environmental stresses like drought or high light intensity. High NADPH levels can enhance biosynthetic pathways essential for growth, while low levels may impair these processes. Moreover, insufficient NADPH could lead to reduced ability to detoxify reactive oxygen species, increasing oxidative stress and compromising plant resilience. Thus, maintaining optimal NADPH levels is vital for supporting both metabolic functions and stress responses.