<Tr> <Td> Y </Td> <Td> 12.5 </Td> <Td> acrocentric </Td> <Td> 57.7 </Td> </Tr> <P> There are two types of centromeres . In regional centromeres, DNA sequences contribute to but do not define function . Regional centromeres contain large amounts of DNA and are often packaged into heterochromatin . In most eukaryotes, the centromere's DNA sequence consists of large arrays of repetitive DNA (e.g. satellite DNA) where the sequence within individual repeat elements is similar but not identical . In humans, the primary centromeric repeat unit is called α - satellite (or alphoid), although a number of other sequence types are found in this region . </P> <P> Point centromeres are smaller and more compact . DNA sequences are both necessary and sufficient to specify centromere identity and function in organisms with point centromeres . In budding yeasts, the centromere region is relatively small (about 125 bp DNA) and contains two highly conserved DNA sequences that serve as binding sites for essential kinetochore proteins . </P> <P> Since centromeric DNA sequence is not the key determinant of centromeric identity in metazoans, it is thought that epigenetic inheritance plays a major role in specifying the centromere . The daughter chromosomes will assemble centromeres in the same place as the parent chromosome, independent of sequence . It has been proposed that histone H3 variant CENP - A (Centromere Protein A) is the epigenetic mark of the centromere . The question arises whether there must be still some original way in which the centromere is specified, even if it is subsequently propagated epigenetically . If the centromere is inherited epigenetically from one generation to the next, the problem is pushed back to the origin of the first metazoans . </P>

Where can the centromere of dna be found