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repetitive DNA

(Science: molecular biology) nucleotide sequences in dNA that are present in the genome as numerous copies. Originally identified by the C0t_ value derived from kinetic studies of dNA renaturation. These sequences are not thought to code for polypeptides. One class of repetitive DNA, termed highly repetitive DNA, is found as short sequences, 5-100 nucleotides, repeated thousands of times in a single long stretch. It typically comprises 3-10% of the genomic DNA and is predominantly satellite DNA. Another class, which comprises 25-40% of the DNA and termed moderately repetitive DNA, usually consists of sequences about 150 to 300 nucleotides in length dispersed evenly throughout the genome and includes alu sequences and transposons.