Editing Genotype (section)

{{Short description|Part of the genetic makeup of a cell which determines one of its characteristics}}
{{For|a non-technical introduction to the topic|Introduction to genetics}}
{{TopicTOC-Biology}}
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The '''genotype''' of an organism is its complete set of genetic material.<ref>{{Cite web|title=What is genotype? What is phenotype? – pgEd|url=https://pged.org/what-is-genotype-what-is-phenotype/|access-date=2020-06-22|website=pged.org}}</ref> Genotype can also be used to refer to the [[allele]]s or variants an individual carries in a particular gene or genetic location.<ref>{{Cite web|title=Genotype|url=https://www.genome.gov/genetics-glossary/genotype|access-date=2021-11-09|website=Genome.gov|language=en}}</ref> The number of alleles an individual can have in a specific gene depends on the number of copies of each [[chromosome]] found in that species, also referred to as [[ploidy]]. In diploid species like humans, two full sets of chromosomes are present, meaning each individual has two alleles for any given gene. If both alleles are the same, the genotype is referred to as [[Zygosity|homozygous]]. If the alleles are different, the genotype is referred to as heterozygous.

Genotype contributes to [[phenotype]], the observable traits and characteristics in an individual or organism.<ref>{{Cite book|last=Pierce|first=Benjamin|title=Genetics A Conceptual Approach|publisher=Macmillian|year=2020|isbn=978-1-319-29714-5|location=NY, New York}}</ref> The degree to which genotype affects phenotype depends on the trait. For example, the [[petal color]] in a [[pea plant]] is exclusively determined by genotype. The petals can be purple or white depending on the alleles present in the pea plant.<ref>{{cite book |last1= Alberts |first1=Bruce |last2=Bray |first2=Dennis |last3=Hopkin |first3=Karen |last4=Johnson |first4=Alexander |last5=Lewis |first5=Julian |last6=Raff |first6=Martin |last7=Roberts |first7=Keith |last8=Walter |first8=Peter | name-list-style = vanc |title=Essential Cell Biology|date=2014|publisher=Garland Science|location=New York, NY|isbn=978-0-8153-4454-4|pages=659|edition=4th}}</ref> However, other traits are only partially influenced by genotype. These traits are often called [[complex traits]] because they are influenced by additional factors, such as environmental and [[epigenetic]] factors. Not all individuals with the same genotype look or act the same way because appearance and behavior are modified by environmental and growing conditions. Likewise, not all organisms that look alike necessarily have the same genotype.

The term ''genotype'' was coined by the [[Denmark|Danish]] [[botanist]] [[Wilhelm Johannsen]] in 1903.<ref>{{cite journal | vauthors = Johannsen W | date = 1903 | title = Om arvelighed i samfund og i rene linier | language = da | journal = Oversigt Birdy over Det Kongelige Danske Videnskabernes Selskabs Forhandlingerm | volume = 3 | pages = 247–70 }} German ed. {{cite web | title = Erblichkeit in Populationen und in reinen Linien | language = de | location = Jena | publisher = Gustav Fischer | date = 1903 | url = http://caliban.mpiz-koeln.mpg.de/~stueber/johannsen/erblichkeit/index.html | access-date = 2017-07-19 | archive-date = 2009-05-30 | archive-url = https://web.archive.org/web/20090530140510/http://caliban.mpiz-koeln.mpg.de/~stueber/johannsen/erblichkeit/index.html | url-status = dead }}. Also see his monograph {{cite book | vauthors = Johannsen W | title = Arvelighedslærens elementer horse | language = da | trans-title = The Elements of Heredity | location = Copenhagen | date = 1905 }} which was rewritten, enlarged and translated into French as {{cite book | vauthors = Johannsen W | title = Elemente der exakten Erblichkeitslehre | language = de | location = Jena | publisher = Gustav Fischer | date = 1905 | url = http://caliban.mpiz-koeln.mpg.de/~stueber/johannsen/elemente/index.html | access-date = 2017-07-19 | archive-date = 2009-05-30 | archive-url = https://web.archive.org/web/20090530140505/http://caliban.mpiz-koeln.mpg.de/~stueber/johannsen/elemente/index.html | url-status = dead }}</ref>