Satellite DNA

<p>Satellite DNA consists of very large arrays of <a href="/facts/Tandem_repeat/V40yCKFJ">tandemly</a> repeating, <a href="/facts/Non-coding_DNA/zyTU8q8M">non-coding DNA</a>. Satellite DNA is the main component of functional <a href="/facts/Centromere/AWxF1ClY">centromeres</a>, and form the main structural constituent of <a href="/facts/Heterochromatin/frJ8HL41">heterochromatin</a>.
</p><p>The name "satellite DNA" refers to the phenomenon that repetitions of a short <a href="/facts/DNA/nB89Iauz">DNA</a> sequence tend to produce a different frequency of the bases <a href="/facts/Adenine/PSeDFBnl">adenine</a>, <a href="/facts/Cytosine/JW20j33u">cytosine</a>, <a href="/facts/Guanine/hoTSpz0x">guanine</a>, and <a href="/facts/Thymine/A5C8MnLN">thymine</a>, and thus have a different density from bulk DNA such that they form a second or "satellite" band(s) when genomic DNA is separated along a cesium chloride <a href="/facts/Density_gradient/V67N07PF">density gradient</a> using <a href="/facts/Buoyant_density_centrifugation/FsaBRl5c">buoyant density centrifugation</a>.
Sequences with a greater ratio of A+T display a lower density while those with a greater ratio of G+C display a higher density than the bulk of genomic DNA. Some repetitive sequences are ~50% G+C/A+T and thus have buoyant densities the same as bulk genomic DNA. These satellites are called "cryptic" satellites because they form a band hidden within the main band of genomic DNA. "Isopycnic" is another term used for cryptic satellites.
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Satellite DNA open-in-new

Satellite DNA