Targeting a DNA sequence for editing by the CRISPR‑Cas9 system requires that a protospacer‑adjacent motif (PAM) sequence appear just downstream of the target sequence. For S. pyogenes Cas9 this PAM is the trinucleotide NGG, where N represents any nucleotide. Assuming a fragment of DNA includes equal amounts of A, C, G, and T bases, how many bases apart, on average, would one expect to find the NGG PAM?

1. variations in a population of moths allow for some of its members to be able to adapt to environmental changes. the better adapted of the moths will be able to survive the change and thus prevail as the “fittest” of the species. (a) describe three mechanisms in which variation can occur within a species population. (b) explain which mechanism or mechanisms would be responsible for the survival of a population of peppered moths better than white moths in an environment affected by industrial soot. justify your answer.

What is used as a template during replication? a- mrna b- trna c- rrna d- dna

Ascientist is investigating the effects of salinity on fish development. he places fertilized fish eggs in an aquarium that contains low salinity and observes their development. what factor would improve experimental design the most? place the fish eggs in the open ocean because that is the natural habitat include another aquarium that has normal salinity to compare to the low salinity aquarium include an aquarium that replaces salt with sugar to confirm that the effects are specific to salt grow algae with the fish eggs in order to provide adequate nutrients to the developing embryos