Pedigree legend: • Circles indicates females; squares are males • Filled outline

Question

Pedigree legend:

• Circles indicates females; squares are males

• Filled outline around names indicates people that are showing the phenotype

• Dotted outline around names indicates carries of that gene

• Purple arrow is for question 1 c

• Ignore the grey squares around some of the names, those are not important for this problem set.

The individuals with an orange outline around their name in the pedigree above have an immune deficiency which makes them more likely to get Spattergroit. Spattergroit causes the skin of those infected to break out in purple pustules, once the infection reaches the uvula speech is impaired. The infection can last for several months, however once healed, these blisters could leave scars, particularly on the face. (Rowling, 2003).

Based on this pedigree chart, answer the questions below.

a. Is the disease likely caused by a dominant or recessive gene? Explain your reasoning.

b. Is this gene autosomal of X-linked? Explain your reasoning.

c. If Calidora Black’s daughter (generation IV, indicated by the purple arrow) mates with an individual that shows the Spattergroit phenotype write the possible genotypes and phenotypes their children can have. In case the gene is X-linked also specify the gender.

The Black Fami Sirius Black 1845 1853 Elladora Black 1850-1931 Isla Black = Bob Hitchens Phineas Nigellus Black 1847-1925 ! Ursula Flint : Belvina Herbert Arcturus Cygnus Black 1889-1943 Violetta Bulstrode Sirius BlackHesper Gamp 1877-1952 Phineas Black Black 1886-1962 BlackFLysandra Yaxley 1884-1959 urs MelaniaLycoris Regulus I BlackMacmillan Black Polluv Dorea Black Potter Pollux Black=Irma Crabbe : Cassiopeia Marius Charlus d tallidora . Harfang Cedrella-Septimus Charis-Caspar Black 1904-1965 1906-1959 1912-1990 Black Longbottom Black Weasley Black Crouch 1915 ack Black Bl .1915-1992 .* 1901-1991 1919- 1973 1920-1977 Lucretia Ignatius 915-1982- Orion Black Alphard WalburgaBlack Cygnus L Druella Black IV: Black Prewett Blik Rosier 1938-1992 1929-1979 .1925-1985.. Sirius Black Regulus Black Bellatrix Rodolphus Andromeda Ted TonkNarcissaLucius Black One son possibl Black Malfoy .. 1955 James Potter = Lilv Evans 959/19602-1996 1961-1979B Lestrange Black 1951-1998 1960- 1981 1960 198 Nymphadora Tonks 1973-1998 Draco Malfov 1980 - Harry Potter 1980 VI

Explanation / Answer

A. The disease is caused by a recessive gene. Because in dominant even a single allele willvexpress itself and the person will be affected. There will be no carrier in dominant but will be in the recessive.

B. The gene is X-linked. Because If trait is X-linked, the male would be affected even by a single recessive allele. This is because male is heterozygous regarding the sex chromosome. So a single allele on X-chromosome (even recessive) will create the expression and male would be affected.

C. In this case as the mother is carrier so it will have two gamates that is both are X chromosomes linked with either recessive (Xc)and either with dominant (XC)and father has also two gamates one is Y chromosome and other X chromosome with recessive allele.(Xc)

So there will be possibility of 50% males to be normal (XCY)and 50% to be affected (XcY)

And 50 % females will be carrier (XcXC) and 50% will be affected (XcXc).

Note-here 'c' denoted recessive allele and 'C' denoted dominant allele.

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