Editing Genetics (section)

=== Notation and diagrams ===
[[File:Pedigree-chart-example.svg|thumb|left|upright=1.1|Genetic pedigree charts help track the inheritance patterns of traits.]]

Geneticists use diagrams and symbols to describe inheritance. A gene is represented by one or a few letters. Often a "+" symbol is used to mark the usual, [[Wild type|non-mutant allele]] for a gene.<ref>{{cite web|url=http://faculty.users.cnu.edu/rcheney/Genetic%20Notation.htm|title=Genetic Notation| vauthors = Cheney RW |publisher=Christopher Newport University|access-date=18 March 2008|archive-url=https://web.archive.org/web/20080103021518/http://faculty.users.cnu.edu/rcheney/Genetic%20Notation.htm|archive-date=3 January 2008}}</ref>

In fertilization and breeding experiments (and especially when discussing Mendel's laws) the parents are referred to as the "P" generation and the offspring as the "F1" (first filial) generation. When the F1 offspring mate with each other, the offspring are called the "F2" (second filial) generation. One of the common diagrams used to predict the result of cross-breeding is the [[Punnett square]].<ref name="Müller-Wille-Parolini_2020">{{cite book |chapter=Punnett squares and hybrid crosses: how Mendelians learned their trade by the book | vauthors = Müller-Wille S, Parolini G |publisher=[[British Society for the History of Science]] / [[Cambridge University Press]] |date=2020-12-09 |series=BJHS Themes |volume=5 |title=Learning by the Book: Manuals and Handbooks in the History of Science |pages=149–165 |doi=10.1017/bjt.2020.12 |s2cid=229344415 |url=https://www.cambridge.org/core/journals/bjhs-themes/article/punnett-squares-and-hybrid-crosses-how-mendelians-learned-their-trade-by-the-book/18A1CE37A6EE536CC1CE1D4FF6FF3174 |access-date=2021-03-29 |url-status=live |archive-url=https://web.archive.org/web/20210329111650/https://www.cambridge.org/core/journals/bjhs-themes/article/punnett-squares-and-hybrid-crosses-how-mendelians-learned-their-trade-by-the-book/18A1CE37A6EE536CC1CE1D4FF6FF3174 |archive-date=2021-03-29}}</ref>

When studying human genetic diseases, geneticists often use [[pedigree chart]]s to represent the inheritance of traits.<ref name=griffiths2000sect229>{{cite book | veditors = Griffiths AJ, Miller JH, Suzuki DT, Lewontin RC, Gelbart|title=An Introduction to Genetic Analysis |year=2000 |isbn=978-0-7167-3520-5 |edition=7th |publisher=W.H. Freeman |location=New York |chapter-url=https://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=iga.section.229 |chapter=Human Genetics}}</ref> These charts map the inheritance of a trait in a family tree.