Question

1) Genetics

a) Which of the following genotypes have one haplotype in common with the genotype aBcdE/ABcDe?

abdeE/ABcDE

ABcDE/ABCDe

abCDE/aBcdE

ABcde/abcde

b) Consider an experiment in which an Hfr strain of E. coli bacteria with the StrS, his+, met+ alleles in its genome is mixed with an F- strain of E. coli with the StrR, his-, and met- alleles in its genome. After the cells have been cultured together for 8 hours, the mixture of cells is plated on minimal media containing Streptomycin. Which genotype do you expect to be most common among the colonies that grow?

F-: StrR, his+ and met+

F-: StrR, his- and met-

F+: StrR, his- and met-

F+: StrR, his+ and met+

Hfr: StrR, his+ and met+

c) When a crossover occurs between a gene of interest and the centromere of the chromosome it is on in a Neurospora cell undergoing meiosis, the resulting ascus will show:

first division segregation

second division segregation

a non-parental ditype

a parental ditype

a tetratype

d) How do you calculate cotransduction frequency?

Answer 1

Answer:

a):

b):"D" is correct:

• We know that Hfr strain is a high frequency recombination strain in which the F plasmid (fertility factor) is integrated in its genome/chromosomal DNA.
• this way, Hfr has ability to transfer the entire genome sequence to its recipient (F- strain), but it requires a long time of physical contact with the recipient due to which the recipient get some gene (long time physical contact is rarely achieved) and remains as F- strain.
• also, there is no back transfer of genes to the Hfr cells from the F- cells.

hence, in this case, only F- strain will survive which has resistance against Streptomycin and able to synthesize its amino acids on minimal media.

which is a recombinant F-: StrR, his+ and met+.

C):"B" is correct:

second divison segregation (SDG)

• also called M2 pattern Because the linear octate will deviate from the 4:4 pattern.
• Seconddivison segregation is used for the calculate the distance of a locus.
• SDG=location and order of genes on the same chromosome arm.