Relationship between chlorophyll and accessory pigments

What Four Accessory Pigments Are Necessary for Photosynthesis to Be Carried Out? | Sciencing

relationship between chlorophyll and accessory pigments

Accessory pigments are light-absorbing compounds, found in photosynthetic organisms, that work in conjunction with chlorophyll a. They include other forms of this pigment, such as chlorophyll b in green algal The six shoulders in the light absorption of water between wavelengths and nm correspond to troughs. Accessory pigments versus chlorophyll a concentrations within the euphotic zone : the consistency of the relationship between accessory pigments and Chl a. A light harvesting complex has a pigment molecule (Chlorophyll a, b, and carotenoid) and is bound to a certain protein. Depending on the.

A longer wavelength is associated with lower energy and a shorter wavelength is associated with higher energy. The types of radiation on the spectrum, from longest wavelength to shortest, are: Visible light is composed of different colors, each having a different wavelength and energy level.

The colors, from longest wavelength to shortest, are: It includes electromagnetic radiation whose wavelength is between about nm and nm.

What is the difference between chlorophyll and accessory pigments? What do they absorb/reflect?

You can see these different colors when white light passes through a prism: Red light has the longest wavelength and the least energy, while violet light has the shortest wavelength and the most energy. Although light and other forms of electromagnetic radiation act as waves under many conditions, they can behave as particles under others. Each particle of electromagnetic radiation, called a photon, has certain amount of energy. Types of radiation with short wavelengths have high-energy photons, whereas types of radiation with long wavelengths have low-energy photons.

relationship between chlorophyll and accessory pigments

However, the various wavelengths in sunlight are not all used equally in photosynthesis. Instead, photosynthetic organisms contain light-absorbing molecules called pigments that absorb only specific wavelengths of visible light, while reflecting others.

The set of wavelengths absorbed by a pigment is its absorption spectrum. In the diagram below, you can see the absorption spectra of three key pigments in photosynthesis: The set of wavelengths that a pigment doesn't absorb are reflected, and the reflected light is what we see as color. For instance, plants appear green to us because they contain many chlorophyll a and b molecules, which reflect green light.

Each photosynthetic pigment has a set of wavelength that it absorbs, called an absorption spectrum. Absorption spectra can be depicted by wavelength nm on the x-axis and the degree of light absorption on the y-axis. The absorption spectrum of chlorophylls includes wavelengths of blue and orange-red light, as is indicated by their peaks around nm and around nm.

As a note, chlorophyll a absorbs slightly different wavelengths than chlorophyll b.

relationship between chlorophyll and accessory pigments

Chlorophylls do not absorb wavelengths of green and yellow, which is indicated by a very low degree of light absorption from about to nm. Optimal absorption of light occurs at different wavelengths for different pigments. Carotenoids are usually red, orange, or yellow pigments, and include the familiar compound carotene, which gives carrots their color. These compounds are composed of two small six-carbon rings connected by a "chain" of carbon atoms.

As a result, they do not dissolve in water, and must be attached to membranes within the cell.

Accessory Pigments -- Driving Question

Carotenoids cannot transfer sunlight energy directly to the photosynthetic pathway, but must pass their absorbed energy to chlorophyll. For this reason, they are called accessory pigments.

relationship between chlorophyll and accessory pigments

One very visible accessory pigment is fucoxanthin the brown pigment which colors kelps and other brown algae as well as the diatoms. Phycobilins are water-soluble pigments, and are therefore found in the cytoplasm, or in the stroma of the chloroplast. They occur only in Cyanobacteria and Rhodophyta. The picture at the right shows the two classes of phycobilins which may be extracted from these "algae".

The vial on the left contains the bluish pigment phycocyanin, which gives the Cyanobacteria their name. The vial on the right contains the reddish pigment phycoerythrin, which gives the red algae their common name. Phycobilins are not only useful to the organisms which use them for soaking up light energy; they have also found use as research tools. Both pycocyanin and phycoerythrin fluoresce at a particular wavelength.

Photosynthetic Pigments

That is, when they are exposed to strong light, they absorb the light energy, and release it by emitting light of a very narrow range of wavelengths. The light produced by this fluorescence is so distinctive and reliable, that phycobilins may be used as chemical "tags".

The pigments are chemically bonded to antibodies, which are then put into a solution of cells. When the solution is sprayed as a stream of fine droplets past a laser and computer sensor, a machine can identify whether the cells in the droplets have been "tagged" by the antibodies.

This has found extensive use in cancer research, for "tagging" tumor cells.