In Neurospora, his2 mutants require the amino acidhistidine for growth, and lys4 mutants require theamino acid lysine. The two genes are on the samearm of the same chromosome, in the ordercentromere - his2 - lys4.A his2 mutant is mated with a lys4 mutant. Draw all ofthe possible ordered asci that could result from meioses in which the following events occurred, accountingfor the nutritional requirements for each ascospore.Ascospores without any copy of a chromosome willabort and die, turning white in the process.a. A single crossover between the centromere and his2b. A single crossover between his2 and lys4c. Nondisjunction during the first meiotic divisiond. Nondisjunction during the second meiotic divisione. A single crossover between the centromere andhis2, followed by nondisjunction during the firstmeiotic divisionf. A single crossover between his2 and lys4,followed by nondisjunction during the firstmeiotic division
In Neurospora, his2 mutants require the amino acid
histidine for growth, and lys4 mutants require the
amino acid lysine. The two genes are on the same
arm of the same chromosome, in the order
centromere - his2 - lys4.
A his2 mutant is mated with a lys4 mutant. Draw all of
the possible ordered asci that could result from meioses in which the following events occurred, accounting
for the nutritional requirements for each ascospore.
Ascospores without any copy of a chromosome will
abort and die, turning white in the process.
a. A single crossover between the centromere and his2
b. A single crossover between his2 and lys4
c. Nondisjunction during the first meiotic division
d. Nondisjunction during the second meiotic division
e. A single crossover between the centromere and
his2, followed by nondisjunction during the first
meiotic division
f. A single crossover between his2 and lys4,
followed by nondisjunction during the first
meiotic division
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