45.Which statement about epigenetic changes is false?a.They may involve methylation.b.They may involve chromosomal protein alterations.c.They may be heritable.d.They are irreversible.$e.They may be present or absent in different cells of the same organism.
46.In which of the following environments is the lac operon strongly transcribed?
47.The most costly way (requires the most ATP) to negatively regulate gene expression is:
48.Once lambda phage inserts into the E. coli genome and becomes a lysogen, it is very stable and rarely enters the lytic life cycle. UV irradiation is one way to get lambda phage towake up, excise from the genome, make copies of itself, and kill its host. How does UV trigger the induction of the lambda lytic cycle?