Photosynthetic pigments

Photosynthetic pigments

Arranged in structures called photosystems

Photosystems

Transmembrane protein complexes found in the thylakoid membranes

A coloured molecule that absorbs light that are needed for photosynthesis

Chlorophyll a

Is in the primary pigment centre

Two forms

→ P680 - photosystems 2

→ P700 - photosystem 1

Appears yellow-green

Absorbs red light

Contains M g atom - when light hits this, a pair of electrons become excited

Chlorophyll b

Absorbs light at wavelengths between 500-640nm

It appears blue-green

One of the accessory pigments

Less abundant than chlorophyll a

Increases the light absorbed

Carotenoids

Absorbs blue light

Reflects yellow and orange light

They absorb light not normally absorbed by chlorophyll’s

What does having more pigments do?

Increases the range of wavelengths that plants can absorb so it increases their ability to photosynthesise

Why do photosystems contain accessory pigments?

Channel more captured light energy to chlorophyll so more electrons can be excited

Why does chlorophyll appear green?

Reflects green light