The Addgene Blog

Master plasmid fundamentals, CRISPR techniques, AAV serotype selection, and antibody applications. Written by scientists, for scientists.

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Recent Posts

Graph showing various categories of viral vector tools and what percentage each tool makes up of the Addgene viral vector item catalog.
a graphic showing the four types of ELISAs.
A flow chart showing the steps of rAAV production. Details in blog post.
AAV infection of retinal neurons.
Overview of the parts of CRISPR. The bacterial chromosome encodes a tracrRNA (in some systems including Cas9), Cas proteins, and a CRISPR array. The CRISPR array is composed of identical repeat sequences and variable spacer sequences. The array is transcribed and processed into crRNAs, each including one repeat and one spacer. In bacteria, these crRNAs are bound by Cas proteins (Cas9 shown here). The repeat sequence base pairs with the tracrRNA, and the spacer sequence is used to target complementary DNA sequences. In laboratory settings, an sgRNA includes the crRNA and tracrRNA sequences in a “single-guide RNA” that performs both functions. Cas9 cuts both the target and nontarget DNA strands upstream of the PAM site found in the nontarget strand.

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