chlorophyll

(noun)

Any of a group of green pigments that are found in the chloroplasts of plants and in other photosynthetic organisms such as cyanobacteria.

Related Terms

Examples of chlorophyll in the following topics:

  • Carotenoids and Phycobilins

    • To aid chlorophylls in the absorption of light not many photosynthetic organisms use carotenoids and phycobilins.
    • They serve two key roles in plants and algae: they absorb light energy for use in photosynthesis, and they protect chlorophyll from photodamage.
    • Phycobiliproteins then pass the light energy to chlorophylls for photosynthesis.The phycobilins are especially efficient at absorbing red, orange, yellow, and green light, wavelengths that are not well absorbed by chlorophyll a.
    • The color of the mats of algae and bacteria is due to the ratio of chlorophyll to carotenoid molecules produced by the organisms.
    • During summertime the chlorophyll content of the organisms is low and thus the mats appear orange, red, or yellow.

  • Absorption of Light

    • Pigments, like chlorophyll and carotenoids, absorb and reflect light at a certain region of the electromagnetic spectrum.
    • There are five major chlorophylls: a, b, c and d, along with a related molecule found in prokaryotes called bacteriochlorophyll.
    • Chlorophyll a absorbs light in the blue-violet region, while chlorophyll b absorbs red-blue light.
    • Neither a or b absorb green light; because green is reflected or transmitted, chlorophyll appears green.
    • (a) Chlorophyll a, (b) chlorophyll b, and (c) β-carotene are hydrophobic organic pigments found in the thylakoid membrane.

  • Bacteriorhodopsin

    • Bacteriorhodopsin acts a proton pump, generating cellular energy in a manner independent of chlorophyll.
    • All other phototrophic systems in bacteria, algae, and plants use chlorophylls or bacteriochlorophylls rather than bacteriorhodopsin.
    • Furthermore, chlorophylls are aided in capturing light energy by other pigments known as "antennas"; these are not present in bacteriorhodopsin-based systems.
    • Last, chlorophyll-based phototrophy is coupled to carbon fixation (the incorporation of carbon dioxide into larger organic molecules) and for that reason is photosynthesis, which is not true for bacteriorhodopsin-based system.

  • Streptophytes and Reproduction of Green Algae

    • Green algae contain the same carotenoids and chlorophyll a and b as land plants, whereas other algae have different accessory pigments and types of chlorophyll molecules in addition to chlorophyll a.

  • Main Structures and Summary of Photosynthesis

    • In multicellular autotrophs, the main cellular structures that allow photosynthesis to take place include chloroplasts, thylakoids, and chlorophyll.
    • Embedded in the thylakoid membrane is chlorophyll, a pigment that absorbs certain portions of the visible spectrum and captures energy from sunlight.
    • Chlorophyll gives plants their green color and is responsible for the initial interaction between light and plant material, as well as numerous proteins that make up the electron transport chain.

  • Processes of the Light-Dependent Reactions

    • Each photosystem consists of multiple antenna proteins that contain a mixture of 300–400 chlorophyll a and b molecules, as well as other pigments like carotenoids.
    • The two photosystems absorb light energy through proteins containing pigments, such as chlorophyll.
    • When a chlorophyll a molecule within the reaction center of PSII absorbs a photon, the electron in this molecule attains a higher energy level.
    • Pigments in the light-harvesting complex pass light energy to two special chlorophyll a molecules in the reaction center.
    • The light excites an electron from the chlorophyll a pair, which passes to the primary electron acceptor.

  • The Two Parts of Photosynthesis

    • In the light-dependent reactions, energy from sunlight is absorbed by chlorophyll and converted into stored chemical energy, in the form of the electron carrier molecule NADPH (nicotinamide adenine dinucleotide phosphate) and the energy currency molecule ATP (adenosine triphosphate).
    • Pigments in the light-harvesting complex pass light energy to two special chlorophyll a molecules in the reaction center.
    • The light excites an electron from the chlorophyll a pair, which passes to the primary electron acceptor.

  • Anoxygenic Photosynthetic Bacteria

    • There are two major types of phototrophy: chlorophyll-based chlorophototrophy and rhodopsin-based retinalophototrophy.
    • Anoxygenic phototrophs have photosynthetic pigments called bacteriochlorophylls ; these are similar to chlorophyll found in eukaryotes.
    • Photosynthesis is achieved using bacteriochlorophyll (BChl) c, d, or e, in addition to BChl a and chlorophyll a, in chlorosomes attached to the membrane.
    • They are related to chlorophylls, which are the primary pigments in plants, algae, and cyanobacteria.

  • Anoxygenic Photosynthesis

    • There are two major types of phototrophy: chlorophyll-based chlorophototrophy and rhodopsin-based retinalophototrophy.
    • Anoxygenic phototrophs have photosynthetic pigments called bacteriochlorophylls (similar to chlorophyll found in eukaryotes).

  • Some Polycyclic Heterocycles

    • Porphyrin is an important cyclic tertrapyrrole that is the core structure of heme and chlorophyll.