What Is Satellite Dna In A Genome

Dna is essential for genome function.

What is satellite dna in a genome. So the name is given as a satellite dna. Genome dispersed repeats and 3 satellite dna which contains short nucleotide sequences repeated as many as thousands of times. The monomer length of satdna sequences ranges from 150 to 400 bp in the majority of plants and animals. Satellite dna is a type of repetitive dna and it classified into minisatellites microsatellites and mini variant repeats based on the number of repetitive units the number of base pairs in each unit and the base composition of the units.

Satellite dna consists of very large arrays of tandemly repeating non coding dna satellite dna is the main component of functional centromeres and form the main structural constituent of heterochromatin. One class of this dna alpha satellite comprises up to 10 of the genome. One short repeating unit of satellite dna ranges from 5 to 300 base pairs depending on the species. Alpha satellite is enriched at all human centromere regions and is competent for de novo centromere assembly.

The name satellite dna refers to the phenomenon that repetitions of a short dna sequence tend to produce a different frequency of the bases adenine cytosine guanine and thymine and. Other articles where satellite dna is discussed. Repetitive dna formerly referred to by the misnomer junk dna comprises a majority of the human genome. The density of dna is a function of its base and sequence and satellite dna with its highly repetitive dna has a reduced or a characteristic density compared to the rest of the genome.

Satellite dna tandemly repeated dna in which the dna fragments involved form minor satellite bands when genomic dna see genome is fractionated by density gradient centrifugation satellite bands of eucaryotic dna fragments are composed of a long series often hundreds of kb in length of tandem repeats. Satellite dna are tandemly repeated and located in the centromere and telomere regions of chromosomes. There can be several different types of satellite dna in a particular genome with. A larger portion of the human genome is made up of repeated sequences and hence it appears as a thick prominent layer on the top of the test tube after the centrifugation.

5 of our genome composed of moderately repetitive dna variable number of tandem repeats 15 100 bp long found between genes can be variable between individuals and used in dna fingerprinting microsatellite paternity testing. Because of the highly repetitive nature of alpha satellite it has been difficult to achieve genome. Because of their nature of separation in the centrifugation process the name satellite dna is given. Such repeats are often found clustered in tandem near the centromeres i e the attachment points for the nuclear spindle fibres that move chromosomes during cell division.

In mammalian genome satellite dna accounts for 10 20 fraction. Satdna sequences are located at heterochromatic regions which are found mostly in centromeric. It carries a variable at rich repeat unit that often forms arrays up to 100 mb.