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The red eyespot of a euglena filters light for the photoreceptor so that only certain wavelengths of light are able to reach the photoreceptor, allowing the euglena to “steer” itself by moving toward light in different intensities in different areas of its photoreceptor. Key: 1. Microtubules that make up the pellicle (see 9.) 2.
Schematic representation of a Euglena cell with red eyespot (9) Schematic representation of a Chlamydomonas cell with chloroplast eyespot (4). The eyespot apparatus (or stigma) is a photoreceptive organelle found in the flagellate or (motile) cells of green algae and other unicellular photosynthetic organisms such as euglenids.
Euglena is a genus of single cell flagellate eukaryotes. It is the best known and most widely studied member of the class Euglenoidea, a diverse group containing some 54 genera and at least 200 species. [1] [2] Species of Euglena are found in fresh water and salt water.
Euglena - schéma de structure 1 noyau 2 chloroplastes 3 granules de paramylon (réserve énergétique proche de l'amidon) 4 vacuole contractile (système de régulation osmotique) 5 kinétosome 6 réservoir 7 flagelle court 8 capteur de lumiere (oeil rudimentaire) 9 stigma ("cache" pour le capteur de lumière permettant de connaitre l ...
Unlike the green euglenids, they lack both an eyespot (stigma), and the paraflagellar body (photoreceptor) that is normally coupled with that organelle. [3] However, while Peranema lack a localized photoreceptor, they do possess the light-sensitive protein rhodopsin , and respond to changes in light with a characteristic "curling behaviour."
Euglena gracilis is a freshwater species of single-celled alga in the genus Euglena. It has secondary chloroplasts , and is a mixotroph able to feed by photosynthesis or phagocytosis . It has a highly flexible cell surface, allowing it to change shape from a thin cell up to 100 μm long to a sphere of approximately 20 μm.
Euglenaceae show the most morphological diversity within the class Euglenophyceae. [3] They are mostly single-celled organisms, except for the genus Colacium.They are free-living or sometimes inhabiting the digestive tracts of animals. [1]
The first attempt at classifying euglenids was done by Ehrenberg in 1830, when he described the genus Euglena and placed it in the Polygastrica of family Astasiae, containing other creatures of variable body shape and lacking pseudopods or lorica.