Which RNA base bonds exist with guanine

The principle of base pairing

The four building blocks of DNA, the bases adenine, cytosine, guanine and thymine, are linked in a precisely defined order to form a long chain - this is the key to the protein's amino acid sequence. In addition to the firm bonds with its two neighbors, each base can also form a loose bond with another base via so-called hydrogen bonds - adenine, however, only with thymine and cytosine only with guanine, these bases are complementary. The DNA is therefore usually in the form of a double strand.

The scientists use this complementary base pairing to fish specific genetic material out of a processed tissue sample: If a DNA probe with a specific base sequence is attached to the chip, only one molecule with a complementary sequence can bind to it. Thus, only a piece of DNA from the sample with the sequence TCCGACAA binds to the AGGCTGTT probe. The scientists also refer to this process as “hybridization”.

Even the slightest deviations, such as the replacement of a single component, can be detected in this way, provided the corresponding probes are on the chip. For example, if the crucial sequence segment comprises eight nucleotides, there are 48, so 65,536 variants - a number that can still be easily accommodated on a chip. The idea of ​​using this property of DNA for aggregation is not new - what is new about the DNA chip is that an enormous number of DNA strands can be arranged extremely densely on a single carrier.