Question

A. Describe two examples (by two different methods) in Eukaryotes where gene expression is regulated after the initial RNA transcript is produced. B. While passing Brown-Forman one night after Bio 331 lab, some students discovered apparent revertants of a bacterium with an loc operator constitutive mutation (09. a. What phenotype did the original mutant have? (In other words, what is the phenotype of an Of mutant7) b. What phenotype did the original "revertant" have? c. If the revertant actually retained its operator mutation and also a had second mutation, this one in the locirane, what type of mutation would we call this second mutation? Explain how the second mutation would make the strain appear wildtype. For the toolbar, press ALT+F10 (PC) or ALT+FN+F10 (Mac).

Answer 1

A). The gene expression in eukaryotes is regulated during RNA processing and transcription, which occurs in the cytoplasm and inside the nucleus, and during the translation of protein. Additional regulation may take place through the process of post-translational modifications of the proteins.

The eukaryotic cells, as compared to prokaryotes consist of intracellular organelles that affix to their complication. In the eukaryotic cells, the DNA is enclosed inside the nucleus of the cell and transcribed into RNA. The freshly formed RNA is after that delivered outside of the nucleus into the cytoplasm, where the RNA is translated into protein by the ribosomes. The processes of translation and transcription are physically divided by the nuclear membrane.

B).

a). Lac O⁺ is the original wild phenotype before the occurrence of the mutation in the operator gene. In constitutive mutants, the genes of lac operon are constantly transcribed. A mutant operator area is faulty in that the repressor cannot attach and therefore transcription cannot be close off.

b) The original phenotype lac operon is a wild type with genotype I⁺ O^{+ Z}+.

c). A reversion or back mutation is a point mutation that re-establish the original sequence and therefore the novel phenotype. The reverse mutation from the abnormal state of a gene reverse to its wild type form, a state can consequence in several possible molecular alterations at the protein level. A right reversion is the turnaround of the original nucleotide change.