DNA replication is for the most part extremely accurate, however errors (<answer>mutations</answer>) do occur.:7.6 The error rate in eukaryotic cells can be as low as 10−8 per nucleotide per replication, whereas for some RNA viruses it can be as high as 10−3. This means that each generation, each human genome accumulates 1–2 new <answer>mutations</answer>. Small <answer>mutations</answer> can be caused by DNA replication and the aftermath of DNA damage and include point <answer>mutations</answer> in which a single base is altered and frameshift <answer>mutations</answer> in which a single base is inserted or deleted. Either of these <answer>mutations</answer> can change the gene by missense (change a codon to encode a different amino acid) or nonsense (a premature stop codon). Larger <answer>mutations</answer> can be caused by errors in recombination to cause chromosomal abnormalities including the duplication, deletion, rearrangement or inversion of large sections of a chromosome. Additionally, the DNA repair mechanisms that normally revert <answer>mutations</answer> can introduce errors when repairing the physical damage to the molecule is more important than restoring an exact copy, for example when repairing double-strand breaks.:5.4
What is it called when errors occur in DNA replication?
mutations