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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| GC-content | 2/2 | https://en.wikipedia.org/wiki/GC-content | reference | science, encyclopedia | 2026-05-05T09:07:14.065445+00:00 | kb-cron |
=== Molecular biology === In polymerase chain reaction (PCR) experiments, the GC-content of short oligonucleotides known as primers is often used to predict their annealing temperature to the template DNA. A higher GC-content level indicates a relatively higher melting temperature. Many sequencing technologies, such as Illumina sequencing, have trouble reading high-GC-content sequences. Bird genomes are known to have many such parts, causing the problem of "missing genes" expected to be present from evolution and phenotype but never sequenced — until improved methods were used.
=== Systematics === The species problem in non-eukaryotic taxonomy has led to various suggestions in classifying bacteria, and the ad hoc committee on reconciliation of approaches to bacterial systematics of 1987 has recommended use of GC-ratios in higher-level hierarchical classification. For example, the Actinomycetota are characterised as "high GC-content bacteria". In Streptomyces coelicolor A3(2), GC-content is 72%. With the use of more reliable, modern methods of molecular systematics, the GC-content definition of Actinomycetota has been abolished and low-GC bacteria of this clade have been found.
== Software tools == GCSpeciesSorter and TopSort are software tools for classifying species based on their GC-contents.
== See also == Codon usage bias
== References ==
== External links == Table with GC-content of all sequenced prokaryotes Taxonomic browser of bacteria based on GC ratio on NCBI website. GC ratio in diverse species.