Question

14..........In Neurospora (a fungus), a complementation test was performed on tive haploid mutants Wild-type in appearance, and means showed abnormal branching. (3 pts) It the table below, complementation crosses were made to establish which mutants rescue the mutation. A complementation group will contain mutants that can rescue the defective phenotype. OWN These results indicate that the mutations were in A) 1 gene. B) 2 genes. C) 3 genes. D) 4 genes. The polarity of DNA synthesis is: E) 5 genes. A 5 → C. 5-2 D. 25 E none of the above During the Sphase of interphase, the state of the DNA can be described as: A a single continuous linear double helix B. a double helix replicated semi-conservatively C. a double helix replicated conservatively D. a triple helix replicated semi-conservatively E none of the above

Answer 1

14) when the progeny of two mutants shows normal phenotype, mutations in the parents are in different genes so that the hybrid gets a normal copy of both genes, if the progeny of two mutants shows mutant phenotype then parents have mutations on the same gene.

two mutants are said to be complementing when progeny has wildtype phenotype.

1,4 and 5 does not complement each other.

2 complements with all others.

3 complements with all others.

so there are three genes

gene A-1,4,5 are alleles

gene B- 2 is the allele

gene C- 3 is the allele

so the answer is C) 3 genes.

15) the DNA polymerase adds new nucleotides to the 3`-OH of the existing nucleic acid, so the direction of DNA synthesis is 5` to 3` so the answer is A) 5` to 3`

16) during S phase DNA replication occurs, DNA is replicated, DNA replication is semiconservative so the answer is B) double helix replicated semiconservatively.