Chapter 10: Photosynthesis Study Guide

Chapter 10: Photosynthesis

Overview of Photosynthesis

  • Photosynthesis is a vital biochemical process for converting light energy into chemical energy.

Chemical Reaction of Photosynthesis

  • The overall equation for photosynthesis is as follows:
    • extCO<em>2+extH</em>2extO+extLightEnergy⇒extC<em>6extH</em>12extO<em>6+extO</em>2ext{CO}<em>2 + ext{H}</em>2 ext{O} + ext{Light Energy} \Rightarrow ext{C}<em>6 ext{H}</em>{12} ext{O}<em>6 + ext{O}</em>2
    • Reactants: Carbon Dioxide (CO2), Water (H2O), and Light.
    • Products: Glucose (C6H12O6) and Oxygen (O2).

Relationship Between Respiration and Photosynthesis

  • Photosynthesis and cellular respiration are interconnected.
    • The process of cellular respiration can be represented by the following equation:
      • extC<em>6extH</em>12extO<em>6+extO</em>2+extADP+extP<em>i⇒extCO</em>2+extH2extO+extATPext{C}<em>6 ext{H}</em>{12} ext{O}<em>6 + ext{O}</em>2 + ext{ADP} + ext{P}<em>i \Rightarrow ext{CO}</em>2 + ext{H}_2 ext{O} + ext{ATP}
    • This illustrates how the products of photosynthesis (glucose and oxygen) are the reactants for cellular respiration.

Organelles Involved in Photosynthesis and Respiration

  • Photosynthesis primarily occurs in chloroplasts.
  • Respiration takes place in mitochondria.

Structure of Chloroplasts

  • Key structural components of chloroplasts include:
    • Stroma: The fluid surrounding the thylakoids within the chloroplast.
    • Granum: A stack of thylakoids where light-dependent reactions occur.
    • Thylakoid: Membrane-bound compartments that house chlorophyll and are involved in the light reactions of photosynthesis.
    • Thylakoid Space: The internal space of a thylakoid.
    • Outer Membrane: The outer boundary of the chloroplast, semi-permeable to ions and small molecules.
    • Intermembrane Space: The space between the outer and inner membranes of the chloroplast.
    • Inner Membrane: The membrane that encloses the stroma and is impermeable to ions and most small molecules.
    • Size: Chloroplasts are approximately 1 μm in diameter.

Light Reactions and the Calvin Cycle

  • Photosynthesis can be divided into two main stages: Light Reactions and the Calvin Cycle.
Light Reactions
  • Occur in the thylakoids.
  • Key inputs: Light and water (H2O).
  • Outputs: NADPH, ATP, and oxygen (O2).
  • Involvement of NADP+: NADP+ is reduced to NADPH during the light reactions, facilitating the transfer of electrons.
Calvin Cycle
  • Occurs in the stroma of the chloroplasts.
  • Key inputs: Carbon dioxide (CO2) and ATP/NADPH from light reactions.
  • Outputs: Sugar (notated as [CH2O] which denotes carbohydrates).

Properties of Light

  • Chloroplasts play a critical role in the absorption and transmission of light.
  • Interaction with light as observed through:
    • Absorbed Light: Light energy absorbed by chlorophyll.
    • Transmitted Light: Light that passes through chloroplasts without being absorbed.
    • Reflected Light: Light that bounces off the surface of the chloroplasts.