Biological pigments

Biological Pigments

Biological pigments are substances produced by living organisms that appear colourful because they absorb certain wavelengths of light and reflect others.
They play a variety of roles including capturing light energy for photosynthesis, attracting pollinators, and offering protection from harmful UV radiation.
Pigments can be classified into categories such as porphyrins, carotenoids, melanins, and flavonoids.

Chlorophyll, located in the chloroplasts of plants, is a type of pigment that absorbs light energy for photosynthesis. It reflects green light, which is why plants appear green.
Hemoglobin, a protein in red blood cells, contains the pigment heme. This pigment binds oxygen and gives blood its red colour.
Myoglobin is a red pigment found in muscle tissues, playing a key role in storing and transporting oxygen within muscle cells.
Carotenoids like beta-carotene reflect orange and yellow light and are responsible for the colours of many fruits and vegetables. They also help with photosynthesis, and certain carotenoids have antioxidant properties.
Melanin is a pigment produced by cells in the skin in humans and animals. It helps to protect the skin from harmful UV radiation.

The biosynthesis of pigments varies and could be quite complex. It often involves multiple biochemical reactions.
For example, the biosynthesis of heme requires eight enzymes to catalyse the conversion of simple molecules into a complex heme structure.
Pigment breakdown or degradation also plays an important role in living organisms.
For example, the breakdown of chlorophyll allows for the colours of other pigments like carotenoids to show in autumn leaves.

Abnormalities in the production, function, or breakdown of biological pigments can cause various disorders.
For example, an inherited inability to produce melanin leads to a condition called albinism.
Hemoglobin abnormalities like Sickle Cell Anemia or Thalassemia result from mutations in the hemoglobin gene, affecting its oxygen-carrying capacity and causing serious health problems.
Porphyrias are a group of rare inherited or acquired disorders of enzymes that normally participate in the production of heme, leading to the build-up of porphyrins or porphyrin precursors.