Its primary component, the Cas9 enzyme (orange), cuts genomic DNA (blue). The enzyme is directed to its target--essentially any sequence along the genome--by hitching it to a strand of guide RNA ...

In the example above, a region of regulatory DNA (blue star) is active only in Cell A. This regulatory DNA controls expression level of Gene Y. Different people have different variations of that ...

within an organism's DNA. For example, no matter whether a person has blue eyes, brown eyes, or green eyes, the alleles for eye color are found in the same area of the same chromosome in all humans.

respectively. The figure shows a strand of DNA (blue) being carried through two rounds of replication.

Watson and Crick's discovery didn't come out of the blue. As early as 1943 Oswald Avery proved what had been suspected: that DNA, a nucleic acid, carries genetic information. But no one knew how ...