Related topics: genome · genes · protein · genetic variation · dna

New evidence emerges on the origins of life

In the beginning, there were simple chemicals. And they produced amino acids that eventually became the proteins necessary to create single cells. And the single cells became plants and animals. Recent research is revealing ...

Mature sperm lack intact mitochondrial DNA, study finds

New research provides insight about the bedrock scientific principle that mitochondrial DNA—the distinct genetic code embedded in the organelle that serves as the powerplant of every cell in the body—is exclusively passed ...

Scientists create first stable semisynthetic organism

Life's genetic code has only ever contained four natural bases. These bases pair up to form two "base pairs"—the rungs of the DNA ladder—and they have simply been rearranged to create bacteria and butterflies, penguins ...

Enzyme corrects more than one million faults in DNA replication

Scientists from the Medical Research Council (MRC) Institute of Genetics and Molecular Medicine (IGMM) at the University of Edinburgh have discovered an enzyme that corrects the most common mistake in mammalian DNA.

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Genetic code

The genetic code is the set of rules by which information encoded in genetic material (DNA or RNA sequences) is translated into proteins (amino acid sequences) by living cells. The code defines a mapping between tri-nucleotide sequences, called codons, and amino acids. A triplet codon in a nucleic acid sequence usually specifies a single amino acid (though in some cases the same codon triplet in different locations can code unambiguously for two different amino acids, the correct choice at each location being determined by context). Because the vast majority of genes are encoded with exactly the same code (see the RNA codon table), this particular code is often referred to as the canonical or standard genetic code, or simply the genetic code, though in fact there are many variant codes. Thus the canonical genetic code is not universal. For example, in humans, protein synthesis in mitochondria relies on a genetic code that varies from the canonical code.

It is important to know that not all genetic information is stored using the genetic code. All organisms' DNA contain regulatory sequences, intergenic segments, and chromosomal structural areas that can contribute greatly to phenotype but operate using distinct sets of rules that may or may not be as straightforward as the codon-to-amino acid paradigm that usually underlies the genetic code (see epigenetics).

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