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The photoreceptors are found in the plasma membrane overlaying the pigmented bodies. The eyespot apparatus of Euglena comprises the paraflagellar body connecting the eyespot to the flagellum . In electron microscopy , the eyespot apparatus appears as a highly ordered lamellar structure formed by membranous rods in a helical arrangement.
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.
Rod cells are photoreceptor cells in the retina of the eye that can function in lower light better than the other type of visual photoreceptor, cone cells.Rods are usually found concentrated at the outer edges of the retina and are used in peripheral vision.
A photoreceptor cell is a specialized type of neuroepithelial cell found in the retina that is capable of visual phototransduction.The great biological importance of photoreceptors is that they convert light (visible electromagnetic radiation) into signals that can stimulate biological processes.
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.
Eyespot, photoreceptor used to sense light direction and intensity; Contractile vacuole, regulates the quantity of water inside a cell; Ventral flagellum; Ventral root; Golgi apparatus; modifies proteins and sends them out of the cell; Endoplasmic reticulum, the transport network for molecules going to specific parts of the cell; Phagosome
Phototaxis is mediated by simple eyespots that consists of a pigment cell and a photoreceptor cell. The photoreceptor cell synapses directly onto ciliated cells, which are used for swimming. The eyespots do not give spatial resolution, therefore the larvae are rotating to scan their environment for the direction where the light is coming from.
The functional unit of the eye is the photoreceptor cell, which contains the opsin proteins and responds to light by initiating a nerve impulse. The light sensitive opsins are borne on a hairy layer, to maximise the surface area. The nature of these "hairs" differs, with two basic forms underlying photoreceptor structure: microvilli and cilia. [26]