For full marks, please write neatly and show your work where appropriate, use pr
ID: 171858 • Letter: F
Question
For full marks, please write neatly and show your work where appropriate, use proper genetic notation and define any abbreviations used. Draw pedigrees using correct symbols for questions concerning human genetics. 1. Zaphod, a space alien from a planet near the star Betelgeuse, meets and marries a phenotypically normal Earth woman, Jane Interestingly, Zaphod himself has a father from his home planet and a human mother. Aliens from the Betelgeus region like Zaphod have pointed noses (specified by allele Q), purple ears (specified by B), and extra long arms (specified by S) All three alleles are dominant to corresponding wild type Earth alleles. The three gene loci are located on autosomes. The three genes are known to have the linkage arrangement where gene B is in the middle of Q and S with the Q-B distance equal to 15 mu and the B-S distance equal to 20 mu. If Zaphod and Jane have children, and there is no genetic interference, what proportion will have: Al Alien phenotypes for nose, ears and arms (1 mark) Bl Earth phenotypes for nose, ears and arms? (1 mark) CJ Alien nose and arms but Earth ears? (1.5 mark) DI Alien nose, but Earth arms and ears? (1.5 mark)Explanation / Answer
Answer:
QBS /qbs (Alien phenotypes for nose, ears, and arms) = 31%
qbs /qbs (Earth phenotypes for nose, ears, and arms) = 31%
QbS/qbs (Alien phenotypes for nose and arms but Earth ears) = 1.5%
Qbs/qbs (Alien phenotypes for nose but Earth arms and ears) = 10%
Explanation:
Alien, Zaphod genotype would be = QBS/qbs
Earth, Jane genotype would be = qbs/qbs
Recombinants due to crossing over between Q & B are =Qbs & qBS
The frequency between them is = 15%
Qbs/qbs (Alien phenotypes for nose but Earth arms and ears) = 10%
= 7.5%
qBS/abc (Earth phenotypes for nose but Alien arms and ears) = 7.5%
Recombinants due to crossing over between B & S are = QBs & qbS
The frequency between them is = 20%
QBs/qbs (Alien phenotypes for nose and ears but Earth arms) = 10%
qbS/qbs (Earth phenotypes for nose and ears but Alien arms) = 10%
Double cross overs are QbS & qBs = 15% * 20% = 0.15 * 0.03 = 3%
QbS/qbs (Alien phenotypes for nose and arms but Earth ears) = 1.5%
qBs/qbs (Earth phenotypes for nose and arms but Alien ears) = 1.5%
Non recombinants (QBS & qbs) = 100 - (15+20+3) = 100 - 38=62
QBS /qbs (Alien phenotypes for nose, ears, and arms) = 31%
qbs /qbs (Earth phenotypes for nose, ears, and arms) = 31%
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