Photosynthesis I: The Light Reaction

Exam 1

Autotrophic

organisms that can make their own food molecules from inorganic sources

Heterotrophic

(animals and fungi) organisms that must consume food molecules from the environment

Photosynthesis

the process of converting light or electromagnetic energy into chemical energy (food molecules), chemical reaction is the reverse of respiration, carbon dioxide is reduced by water to make glucose and oxygen

Respiration

glucose is oxidized by oxygen to make carbon dioxide and water

Light

made up of electromagnetic waves that carry energy

Visible light

carries enough energy to excite electrons in photosynthetic pigments while being less damaging than shorter-wavelength UV radiation

Pigment molecules

molecules that plants have that can absorb light, ex: chlorophyll

Anythocyanins

water-soluble (Hydrophilic), red-purple pigments, protect against UV-damage, important for pollinator attraction and seed dispersal

Carotenoids

Hydrophobic, yellow-orange pigments, protect agains UV-damage, important for pollinator attraction

Thylakoids

disc like membrane compartments in chloroplasts arranged into stacks called grana, where light absorption occurs inside chloroplasts

Photosystems

thylakoid transmembrane proteins that bind chlorophyll and other pigments

Antenna pigments

outer photosystem-bound chlorophylls, capture light (photons) which energetically excite electrons

Reaction center

from excitation energy (not electrons) is transfered between antennae chlorophyll molecules

Photophosphorylation

movement of electrons is coupled to pumping of protons into the theylakoid lumen, creating an electrochemical gradient used for making ATP

Electron carriers

plastoquinone and plastocyanin

Plastoquinone (PQ)

electron carrier, lipid

Plastocyanin (PC)

electron carrier, protein