Skip to main content
Select Source:

rhodopsin

rhodopsin (visual purple) The light-sensitive pigment found in the rods of the vertebrate retina. It consists of a protein component, opsin, linked to a nonprotein chromophore, retinal (or retinene), a derivative of vitamin A. Light falling on the rod is absorbed by the retinal, which changes its form and separates from the opsin component; this initiates the transmission of a nerve impulse to the brain. The great sensitivity of rhodopsin allows vision in dim light (night vision). See also dark adaptation.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"rhodopsin." A Dictionary of Biology. . Encyclopedia.com. 17 Nov. 2018 <https://www.encyclopedia.com>.

"rhodopsin." A Dictionary of Biology. . Encyclopedia.com. (November 17, 2018). https://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/rhodopsin-0

"rhodopsin." A Dictionary of Biology. . Retrieved November 17, 2018 from Encyclopedia.com: https://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/rhodopsin-0

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

rhodopsin

rhodopsin The pigment in the rod cells of the retina of the eye, also known as visual purple, consisting of the protein opsin and retinaldehyde, which is responsible for the visual process. In cone cells of the retina the equivalent protein is iodopsin. See vitamin A; dark adaptation; vision.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"rhodopsin." A Dictionary of Food and Nutrition. . Encyclopedia.com. 17 Nov. 2018 <https://www.encyclopedia.com>.

"rhodopsin." A Dictionary of Food and Nutrition. . Encyclopedia.com. (November 17, 2018). https://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/rhodopsin

"rhodopsin." A Dictionary of Food and Nutrition. . Retrieved November 17, 2018 from Encyclopedia.com: https://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/rhodopsin

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

rhodopsin

rhodopsin (visual purple) The visual pigment found in rod cells in the retina of vertebrates. It is composed of a protein, called an opsin, and retinol, and has an absorption maximum at 500 nm.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"rhodopsin." A Dictionary of Zoology. . Encyclopedia.com. 17 Nov. 2018 <https://www.encyclopedia.com>.

"rhodopsin." A Dictionary of Zoology. . Encyclopedia.com. (November 17, 2018). https://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/rhodopsin

"rhodopsin." A Dictionary of Zoology. . Retrieved November 17, 2018 from Encyclopedia.com: https://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/rhodopsin

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

rhodopsin

rhodopsin (visual purple) (roh-dop-sin) n. a pigment in the retina of the eye consisting of retinal and a protein. The presence of rhodopsin is essential for vision in dim light. See rod.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"rhodopsin." A Dictionary of Nursing. . Encyclopedia.com. 17 Nov. 2018 <https://www.encyclopedia.com>.

"rhodopsin." A Dictionary of Nursing. . Encyclopedia.com. (November 17, 2018). https://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/rhodopsin

"rhodopsin." A Dictionary of Nursing. . Retrieved November 17, 2018 from Encyclopedia.com: https://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/rhodopsin

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

rhodopsin

rho·dop·sin / rōˈdäpsən/ • n. a purplish-red light-sensitive pigment present in the retinas of humans and many other animal groups.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"rhodopsin." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 17 Nov. 2018 <https://www.encyclopedia.com>.

"rhodopsin." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. (November 17, 2018). https://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/rhodopsin

"rhodopsin." The Oxford Pocket Dictionary of Current English. . Retrieved November 17, 2018 from Encyclopedia.com: https://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/rhodopsin

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Rhodopsin

Rhodopsin

Definition

Rhodopsin is the visual pigment that "senses" light in the rod cells of the retina.

Where is rhodopsin?

Rhodopsin is found at the back of the eye, in the retina. The retina is the area of the eye that senses light, interprets that information, and transmits it to the brain for further interpretation. Two types of light-sensing cells are found in the retina: rods and cones. In a simplified explanation, rod cells are responsible for black and white vision, whereas cone cells are responsible for color vision. This is true as far as it goes, but there are many more differences between rods and cones.

In rod cells, rhodopsin is responsible for phototransduction, the process of turning light into chemical and electrical energy. Rhodopsin is responsible for phototransduction in rod cells, but not in cone cells. Three different proteins, similar to rhodopsin, govern phototransduction in the cone cells. Each of these three phototransducers responds to a different color of light, which allows persons with normal color vision to see the entire color spectrum.

In order to understand more of the structure, function, and location of rhodopsin, a discussion of cells and cell membranes is necessary. Every human cell has a cell membrane that separates the environment inside the cell (intracellular environment) from the extracellular (outside the cell) environment. Cell membranes are made up of lipids, which are hydrophobic substances. Hydrophobic literally means "fear of water." Oil is an example of a hydrophobic substance. If oil is added to water, the oil will separate itself from the water. Basically, the lipids in the cell membrane form a similar water-excluding ball, but the inside of the ball will contain water (and other intracellular fluids). Each rhodopsin molecule crosses the cell membrane seven times, and each area of the protein in the cell membrane is called a transmembrane domain. These transmembrane domains (which are hydrophobic) dictate an interesting structure for rhodopsin. Imagine folding a hose seven times to hold it in your hand. The structure for rhodopsin is at least that complex. One reason to mention that rhodopsin has the seven transmembrane domains is because that structure is common to G proteins, and rhodopsin is a G protein. G proteins are generally involved in a biological cascade. A biological cascade is a system where a small initial input (like a brief flash of light) can result in a rather large output.

How does rhodopsin turn light into a chemical signal?

Rhodopsin is a combination of two different molecules, retinal and opsin. Retinal is a derivative of vitamin A, and opsin is a protein. When rhodopsin is not activated, retinal is in the 11-cis configuration. When light hits 11-cis retinal, it changes its shape to become all-trans retinal. This is the only light-sensitive step in vision (in the rod cells). What the configurations are called, and what those names mean is not as important as the fact that this light-dependent change in conformation results in light being converted into chemical energy.

Once retinal reaches the all-trans conformation, opsin also changes its shape. The new opsin-retinal complex is called metarhodopsin II. Metarhodopsin II is a semistable complex that is the active form of rhodopsin. Metarhodopsin II, unlike the inactive rhodopsin, is able to bind a protein called transducin. Each metarhodopsin II can bind to many transducins (literally hundreds). These transducins then cause a decrease in cGMP concentration, and one transducin molecule can cause the breakdown of more than 1,000 cGMP per second. One can clearly see why the G protein cascades are excellent systems for amplifying a signal.

Mutations in rhodopsin

Mutations in rhodopsin can result in two different disorders—retinitis pigmentosa and congenital stationary night blindness. Retinitis pigmentosa (RP) affects about one in 3,000 persons living in the United States, and about 1.5 million persons worldwide. Many mutations, not just mutations of the rhodopsin gene , lead to RP. The disorder may be inherited in an X-linked recessive fashion in 8% of all cases, an autosomal dominant fashion in 19% of cases, or as an autosomal recessive disorder in 19% of all cases. In the rest of the cases (54%), the mutations do not follow classical genetic patterns of inheritance . Mutations in rhodopsin have been found to cause approximately 20% of the autosomal dominant form of RP. The rhodopsin gene is located at the 3q locus of chromosome 3.

Patients with retinitis pigmentosa exhibit symptoms that include night blindness, abnormal pigment accumulation in the retina, and a progressive decrease in the visual fields. The patient's vision decreases from the outermost edges in. The age of onset of the disorder may be as young as six months, but most patients experience the first symptoms between ages 10 and 30. In RP, the patient's rod cells usually degenerate first, followed by a loss of cone cells.

Symptoms may often present after a motor vehicle accident. Not only is the age of onset variable, but the severity of the disease is as well. Patients with the same mutation, even within the same family, exhibit differing severities of the disorder. Mutations in rhodopsin may also cause autosomal recessive cases of RP.

Congenital stationary night blindness (CSNB) is another disorder that can be caused by mutations in the rhodopsin gene. Patients with CSNB, as may be deduced from the name, experience night blindness. However, unlike RP, patients with CSNB do not experience degeneration (death) of cells of the retina (rod and cone cells). Patients with CSNB are thought to have an overactive transducin molecule, which prevents their rods from functioning normally. A mutation in transducin, which also causes CSNB, supports this theory, since this transducin is also thought to be overly active.

Treatment

As of 2001, no effective treamtment for RP exists. However, new treatments are being explored for RP. Experiments in rats have shown that rod cells can be affected by gene therapy . Although gene therapy has not been successfully demonstrated as of this printing, at least the hope now exists that eventually gene therapy may be applied to the problem of RP. Previously, addition of a new gene into a non-dividing cell line had been thought to be technically insurmountable. Another experiment in rodents offers hope for those who have autosomal recessive RP. In rats with autosomal recessive RP, retinal pigment transplantation has successfully treated them according to Columbia University's Retinal Transplant newsletter. This technique might prove promising in humans.

Prognosis

The prognosis for persons with RP is extremely variable. Persons with CSNB will experience night blindness throughout their lives.

Resources

WEBSITES

"A guide to retinitis pigmentosa." The British Retinitis Pigmentosa Society. <http://www.brps.demon.co.uk/Graphics/G_Guide.html#SYMPTOMS>.

Robbins, Alexandra. "Congenital stationary night blindness." <http://130.132.19.190/thom/reviews/cnsb.html>.

Michael V. Zuck, PhD

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Rhodopsin." Gale Encyclopedia of Genetic Disorders. . Encyclopedia.com. 17 Nov. 2018 <https://www.encyclopedia.com>.

"Rhodopsin." Gale Encyclopedia of Genetic Disorders. . Encyclopedia.com. (November 17, 2018). https://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/rhodopsin-0

"Rhodopsin." Gale Encyclopedia of Genetic Disorders. . Retrieved November 17, 2018 from Encyclopedia.com: https://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/rhodopsin-0

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Rhodopsin

Rhodopsin

Definition

Rhodopsin is the visual pigment that "senses" light in the rod cells of the retina.

Where is rhodopsin?

Rhodopsin is found at the back of the eye, in the retina. The retina is the area of the eye that senses light, interprets that information, and transmits it to the brain for further interpretation. Two types of light-sensing cells are found in the retina: rods and cones. In a simplified explanation, rod cells are responsible for black and white vision, whereas cone cells are responsible for color vision. This is true as far as it goes, but there are many more differences between rods and cones.

In rod cells, rhodopsin is responsible for phototransduction, the process of turning light into chemical and electrical energy. Rhodopsin is responsible for phototransduction in rod cells, but not in cone cells. Three different proteins, similar to rhodopsin, govern phototransduction in the cone cells. Each of these three phototransducers responds to a different color of light, which allows persons with normal color vision to see the entire color spectrum.

In order to understand more of the structure, function, and location of rhodopsin, a discussion of cells and cell membranes is necessary. Every human cell has a cell membrane that separates the environment inside the cell (intracellular environment) from the extracellular (out-side the cell) environment. Cell membranes are made up of lipids, which are hydrophobic substances. Hydrophobic literally means fear of water. Oil is an example of a hydrophobic substance. If oil is added to water, the oil will separate itself from the water. Basically, the lipids in the cell membrane form a similar water-excluding ball, but the inside of the ball will contain water (and other intracellular fluids). Each rhodopsin molecule crosses the cell membrane seven times, and each area of the protein in the cell membrane is called a transmembrane domain. These transmembrane domains (which are hydrophobic) dictate an interesting structure for rhodopsin. Imagine folding a hose seven times to hold it in your hand. The structure for rhodopsin is at least that complex. One reason to mention that rhodopsin has seven transmembrane domains is because that structure is common to G proteins, and rhodopsin is a G protein. G proteins are generally involved in a biological cascade. A biological cascade is a system where a small initial input (like a brief flash of light) can result in a rather large output.

How does rhodopsin turn light into a chemical signal?

Rhodopsin is a combination of two different molecules, retinal and opsin. Retinal is a derivative of vitamin A and opsin is a protein. When rhodopsin is not activated, retinal is in the 11-cis configuration. When light hits 11-cis retinal, it changes its shape to become alltrans retinal. This is the only light-sensitive step in vision (in the rod cells). What the configurations are called, and what those names mean is not as important as the fact that this light-dependent change in conformation results in light being converted into chemical energy.

Once retinal reaches the all-trans conformation, opsin also changes its shape. The new opsin-retinal complex is called metarhodopsin II. Metarhodopsin II is a semistable complex that is the active form of rhodopsin. Metarhodopsin II, unlike the inactive rhodopsin, is able to bind a protein called transducin. Each metarhodopsin II can bind to many transducins (literally hundreds). These transducins then cause a decrease in cGMP concentration, and one transducin molecule can cause the breakdown of more than 1,000 cGMP per second. One can clearly see why the G protein cascades are excellent systems for amplifying a signal.

Mutations in rhodopsin

Mutations in rhodopsin can result in two different disorders—retinitis pigmentosa and congenital stationary night blindness, Retinitis pigmentosa (RP) affects about one in 3,000 persons living in the United States, and about 1.5 million persons worldwide. Many mutations, not just mutations of the rhodopsin gene , lead to RP. The disorder may be inherited in an X-linked recessive fashion in 8% of all cases, an autosomal dominant fashion in 19% of cases, or as an autosomal recessive disorder in 19% of all cases. In the rest of the cases (54%), the mutations do not follow classical genetic patterns of inheritance . Mutations in rhodopsin have been found to cause approximately 20% of the autosomal dominant form of RP. The rhodopsin gene is located at the 3q locus of the chromosome .

Patients with retinitis pigmentosa exhibit symptoms that include night blindness, abnormal pigment accumulation in the retina, and a progressive decrease in the visual fields. The patient's vision decreases from the outermost edges in. The age of onset of the disorder may be as young as six months, but most patients experience the first symptoms between ages 10 and 30. In RP, the patient's rod cells usually degenerate first, followed by a loss of cone cells.

Symptoms may often present after a motor vehicle accident. Not only is the age of onset variable, but the severity of the disease is as well. Patients with the same mutation, even within the same family, exhibit differing severities of the disorder. Mutations in rhodopsin may also cause autosomal recessive cases of RP.

Congenital stationary night blindness (CSNB) is another disorder that can be caused by mutations in the rhodopsin gene. Patients with CSNB, as may be deduced from the name, experience night blindness. However, unlike RP, patients with CSNB do not experience degeneration (death) of cells of the retina (rod and cone cells). Patients with CSNB are thought to have an overactive transducin molecule, which prevents their rods from functioning normally. A mutation in transducin which also causes CSNB supports this theory, since this transducin is also thought to be overly active.

Treatment and management

No effective treatment for RP exists. However, new treatments are being explored for RP. Experiments in rats have shown that rod cells can be affected by gene therapy . Although gene therapy has not been successfully demonstrated as of this printing, at least the hope now exists that eventually gene therapy may be applied to the problem of RP. Previously, addition of a new gene into a non-dividing cell line had been thought to be technically insurmountable. Another experiment in rodents offers hope for those who have autosomal recessive RP. In rats with autosomal recessive RP, retinal pigment transplantation has successfully treated them according to Columbia University's Retinal Transplant newsletter. This technique might prove promising in humans.

Prognosis

The prognosis for persons with RP is extremely variable. Persons with CSNB will experience night blindness throughout their lives.

Resources

WEBSITES

"A guide to retinitis pigmentosa." The British Retinitis Pigmentosa Society. <http://www.brps.demon.co.uk/Graphics/G_Guide.html#SYMPTOMS>.

Robbins, Alexandra. "Congenital stationary night blindness." <http://130.132.19.190/thom/reviews/cnsb.html>.

Michael V. Zuck, PhD

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Rhodopsin." Gale Encyclopedia of Genetic Disorders. . Encyclopedia.com. 17 Nov. 2018 <https://www.encyclopedia.com>.

"Rhodopsin." Gale Encyclopedia of Genetic Disorders. . Encyclopedia.com. (November 17, 2018). https://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/rhodopsin

"Rhodopsin." Gale Encyclopedia of Genetic Disorders. . Retrieved November 17, 2018 from Encyclopedia.com: https://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/rhodopsin

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.