Summary
The green pigment in chloroplasts that absorbs mainly red and blue light.
In depth
Chlorophyll a and b absorb strongly at about 430 and 660 nm and reflect green. A porphyrin ring holds magnesium. Accessory pigments (carotenoids) widen the spectrum and protect against excess light.
In autumn, chlorophyll breaks down revealing carotenoids.
Light excites electrons in chlorophyll to a higher level; that energy passes through antenna pigments to a reaction centre. Magnesium sits at the centre of the porphyrin ring and a long phytol tail anchors it in the membrane.
Key idea: chlorophyll reflects green because it absorbs red and blue most strongly.
Chlorophyll a is the primary pigment found in all oxygenic photosynthesisers, and chlorophyll b widens the absorption range. Chlorophyll has a long phytol tail anchoring it in the thylakoid membrane. Light-harvesting complexes funnel energy to a reaction centre at the speed of picoseconds, with a very high efficiency. Chlorophyll synthesis needs light in angiosperms, so seedlings grown in darkness are yellow (etiolated).
Autumn colours appear when chlorophyll breaks down and reveals carotenoids, while anthocyanins are newly made. Iron deficiency or magnesium deficiency causes chlorosis. Paper chromatography separates pigments by solubility: carotene travels furthest, and chlorophyll b the least.
Example: in strong light, excess energy is dissipated as heat via the xanthophyll cycle, which protects the leaf.
Frequently asked questions
What is Chlorophyll?
The green pigment in chloroplasts that absorbs mainly red and blue light.
Which area of biology covers Chlorophyll, and how advanced is it?
Chlorophyll is one of the 56 topics in Plant Biology. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Photosynthetic Pigments, Z-Scheme of Electron Transport, Calvin Cycle.
Can you give an example of Chlorophyll?
Paper chromatography separates pigments by solubility.
What should I learn before Chlorophyll?
Chlorophyll is a Beginner topic, so no earlier topic is required. Other Beginner topics in Plant Biology that pair well with it include Plant Kingdom, Photosynthesis, Roots.
What topics are related to Chlorophyll?
The closest topics to Chlorophyll are Photosynthetic Pigments, Z-Scheme of Electron Transport, Calvin Cycle, Plant Nutrition and Mineral Deficiency. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Chlorophyll?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Chlorophyll. To practise the whole of Plant Biology, use the Plant Biology quiz.
How is Chlorophyll different from Photosynthetic Pigments?
Chlorophyll: The green pigment in chloroplasts that absorbs mainly red and blue light. Photosynthetic Pigments: Chlorophylls, carotenoids and xanthophylls absorb different wavelengths and widen the usable light spectrum. Read both side by side and note what each one explains.
How should I study Chlorophyll step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Photosynthetic Pigments and explain the difference aloud. Finally, take the Plant Biology quiz and come back to this page for any question you miss.