Question

What is satellite DNA? Explain.

Answer 1

Explanation :

1. Satellite DNA is made up of small sequences that are replicated many times. Satellite DNA is made up of vast clusters of non-coding, tandemly repeating DNA. Satellite DNA is the primary structural component of heterochromatin and is found in functioning centromeres.
2. When genomic DNA is separated on a density gradient, repetitions of a short DNA sequence yield a distinct frequency of the bases adenine, cytosine, guanine, and thymine, and hence have a different density from bulk DNA, forming a second or "satellite" band. Sequences with a higher ratio of A+T have a lower density than the bulk of genomic DNA, while those with a higher ratio of G+C have a higher density.
3. Since some repeating sequences are 50 percent G+C/A+T, they float at the same density as bulk genomic DNA. Because they form a band buried within the main band of genomic DNA, these satellites are known as "cryptic" satellites. Another term for cryptic satellites is “isopycnic.”
4. We can conclude that satellite DNA is highly repetitive and the have short DNA sequences.