3-6. Several mutant E. coli or mouse alleles are described below. For each, answ
ID: 206585 • Letter: 3
Question
3-6. Several mutant E. coli or mouse alleles are described below. For each, answer (a) and (a). Predict the mutant phenotype, focusing on the molecular phenotype (the effect on relevant process, for example DNA replication). Describe whether you expect the process would be disrupted completely or partially, and in what way it would be changed. You don't need to speculate about the whole-organism phenotype. (b) Predict whether the mutation would be recessive or dominant to a wild-type allele (Although E. coli is haploid, assume that you can generate cells diploid for the gene in question; one copy of the gene has the mutation listed, and the other copy is wild-type). Assume no haploinsufficiency. 4. A null (complete loss of function) allele of the subunit of E. coli DNA pol III. 5. A mutation in the coding sequence of dnaA. The mutant DnaA protein can still bind DNA normally, but it can't bind at all to other DnaA proteins. 6. A mutation in the anaA coding sequence that encodes a mutant protein that cannot bind either DNA or other DnaA proteins 7. A loss of function allele of Histone H1.Explanation / Answer
4. Beta subunit of DNA polymerase acts as clamp to hold DNA that helps in mounting of core enzyme to DNA. Null mutation will completely stop DNA replication process as it doesn't allow the binding of core enzyme on DNA strand.
The mutation will be recessive to wild type allele. Normal allele would provide functional beta subunit to the mutant protein.
5. 9 mer DnaA proteins are required to initiate DANA replication. So if mutant is unable to bind DnaA protein it will inhibit the replication process almost completely. Because even 6-mer DnaA has low affinity replication potential.
It will be recessive mutation. Normal copy of gene can complement the mutant.
6. No DNA replication will occur as it won't bind to DNA. And the mutation will be recessive.
7. It won't affect replication process at all. Recessive mutation.
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