An increasingly popular mechanism of gene knockout in bacterial cells is to use the crispr/cas9 system. the system uses a single-guide rna (sgrna) to direct the crispr associated protein 9 (cas9) endonuclease enzyme to a gene of interest. here, the cas9 protein will create a blunt, double-stranded break in the dna. the cas9 protein simply cuts, however, and does not directly cause a mutation to occur. by what mechanism does this system cause mutations?

CRISPR-Cas9 editing has offered a breakthrough in the world of science. Various scientists are interested in this and have effectively utilized this technique in editing DNA. The application of guide RNA is not novel, however, its process of mediating caspases towards the target sequences is a tremendous achievement.  

Though the mutations are reported, however, they are not reproducible yet. The mechanisms of DNA mutations through CRISPR-Cas have not demonstrated any kind of solid pathway, although it is reported to result in single base pair deletions in DNA distant from its activity site resulting in gene impairment.  

After the application of CRISPR for editing DNA, large mutations were witnessed in the sequences of DNA, that is, thousand-kilo base away from its site of activity. However, no experimental data offering the precise mechanism is available yet.  

the sphincter muscles at the end of the digestive tract is the anus.

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.