Related: Going viral: 6 new findings about viruses You can also think of spacers like 'Wanted' posters, providing a snapshot of the bad guys so they can be easily spotted and brought to justice. These spacers serve as a bank of memories, which enables the bacteria to recognize the viruses if they should ever attack again. Short palindromic repeats appear throughout CRISPR regions of DNA, with each repeat bookended by 'spacers.' Bacteria swipe such spacers from viruses that have attacked them, meaning they incorporate a bit of viral DNA into their own genome. A palindrome, like the word 'racecar,' reads the same forward as it does backward similarly, in a palindromic sequence, bases on one side of the DNA ladder match those on the opposing side when you read them in opposite directions.įor example, a super simple palindromic sequence might look like this: In a CRISPR region, these bases appear in the same order several times, and in these repeated segments, they form what's known as 'palindromic' sequences, according to the Max Planck Institute. Each rung contains two chemical bases bound together: A base called adenine (A) links up to another called thymine (T), and the base guanine (G) pairs with cytosine (C). When we talk about repeats in the genetic code, we're talking about the ordering of rungs within the spiral ladder of a DNA molecule. (Image credit: Shutterstock)ĬRISPRs: The term 'CRISPR' stands for 'clusters of regularly interspaced short palindromic repeats' and describes a region of DNA made up of short, repeated sequences with so-called 'spacers' sandwiched between each repeat. DNA is a double-stranded molecule whose 'rungs' are made up of one of two base pairs: adenine paired with thymine or cytosine paired with guanine.

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