A

intro to photosynthesis

overview of photosynthesis

photosynthesis - releases O2, takes in CO2, occurs in plants, protists, and some bacteria

}}6CO2 + 6H2O → C6H12O6 + 6O2}}

cellular respiration - releases CO2, takes in O2, occurs in humans and animals

}}6CO2 + C6H12O6 → 6H2O + 6CO2}}

  • autotrophs: producers, organisms that make their own food using photosynthesis, obtain carbon from inorganic molecules such as CO2
  • heterotrophs: consumers, organisms that get carbon from breaking down organic molecules from other organisms, usually autotrophs

photosynthesis contains many reactions that typically occur in 2 stages.

  1. stage 1: light-dependant reactions: converts light energy to chemical energy, makes ATP

    1. splits the water molecule, and releases O2

  2. stage 2: light-independent reactions: runs on energy supplied by NADPH + ATP

    1. NADPH: a product of H2O molecule on coenzyme NADP+
    2. both are recycled to go back to the first stage

light-dependent reactions are executed by molecules located in a thylakoid membrane.

  • thylakoid membrane: inner membrane system that carries out light-dependant reactions in chloroplasts and cyanobacteria
    • folds in the membrane make disks or tuykaloids

light-independent reactions run in stroma

  • stroma: thick cytoplasm-like fluid that fills a chloroplast

sunlight as an energy source

blue and red lights fuel photosynthesis most effectively.

  • wavelength: distance between crests of 2 waves, measured in nanometers
    • visible light travels between 380-750 nm
  • pigment: organic molecule that absorbs light of specific wavelengths
  • photon: packs of energy w/ a related wavelength

pigments have a light-trapping region, a carbon chain or ring that have single bonds alternating with double bonds, so electrons can move freely amongst the atoms

  • can easily absorb certain photons

wavelengths that aren’t absorbed are reflected, and that reflected light makes our perception of color. the most common instance of this is chlorophyll.