Satellite DNA
Satellite DNA
Satellite DNA (pronounced: /ˈsætəlaɪt diːeɪnˈeɪ/) is a type of DNA that is highly repetitive and non-coding. It is found in the genome of many organisms and is named for its isolation from the main-band DNA by density gradient centrifugation.
Etymology
The term "satellite DNA" was coined in the 1960s when these sequences were observed to form a secondary or "satellite" band during density gradient centrifugation, separate from the main band of DNA.
Characteristics
Satellite DNA is characterized by its high degree of repetition, with the same sequence repeated many thousands or even millions of times. These sequences are typically found in heterochromatin, particularly in the centromere and telomere regions of chromosomes. Despite being non-coding, satellite DNA plays important roles in maintaining chromosome structure and function.
Types of Satellite DNA
There are several types of satellite DNA, including:
- Satellite I DNA: This is the most common type of satellite DNA and is typically found in the centromeric region of chromosomes.
- Satellite II DNA: This type of satellite DNA is less common and is typically found in the telomeric region of chromosomes.
- Satellite III DNA: This is the least common type of satellite DNA and is typically found in the heterochromatic region of chromosomes.
Related Terms
- Centromere: The region of a chromosome where the two sister chromatids are most closely attached.
- Telomere: The protective cap at the end of a chromosome.
- Heterochromatin: A tightly packed form of DNA, which comes in multiple varieties.
- Genome: The complete set of genes or genetic material present in a cell or organism.
External links
- Medical encyclopedia article on Satellite DNA
- Wikipedia's article - Satellite DNA
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