🎨 Accessory Pigments – The Helpers
🔹 What are Accessory Pigments?
These are pigments found in plant cells in addition to chlorophyll-a. They help absorb light and pass that energy to chlorophyll-a.
📘 Definition:
Accessory pigments are pigments other than chlorophyll-a that help in collecting sunlight for photosynthesis.
🌿 Types of Accessory Pigments:
- Chlorophyll b – present in plants.
- Carotenoids – these are yellow, orange, and red pigments. They include:
- Carotenes – orange (like in carrots)
- Xanthophylls – yellow (like in corn or autumn leaves)
- Phycobilins – found in red algae and cyanobacteria (also called blue-green algae).
⚙️ Function of Accessory Pigments
Accessory pigments:
- Absorb light that chlorophyll-a cannot absorb well
- Transfer the energy to chlorophyll-a for use in photosynthesis
Think of it like a team working together to catch sunlight:
- Accessory pigments are like assistants who gather energy and hand it over to the main worker — chlorophyll-a.
🔁 Order of Energy Transfer
The energy from sunlight flows in this order:
🔸 Accessory pigments → 🔸 Chlorophyll b → 🔸 Chlorophyll a
This ensures that energy is efficiently transferred and used to power photosynthesis.
📈 Absorption Spectrum
🔍 What is Absorption Spectrum?
It’s a graph that shows which colors (wavelengths) of light a pigment can absorb.
Each pigment has its own absorption pattern, like a fingerprint.
📏 Absorption Peaks:
These are the points on the graph where the pigment absorbs the most light.
For example:
- Chlorophylls absorb best at:
- 430 nm (blue light)
- 670 nm (red light)
- Carotenoids absorb light at different peaks, mostly in the blue-green range.