(a) Reaptitive DNA are those which have a nucleotide sequence which is repeated over and over gain. Satellite DNA is a form of repetitive DNA. Satellite DNA are highly repeated DNA. Satellites are of two types—micro-satellites and mini satellites, depending upon the base composition, length of segment and the number of repetitive units.Satellites do not code for proteins, but have a major role to play in DNA fingerprinting.
(b) mRNA (messenger RNA) − It serves as a template for protein synthesis. DNA is transcribed to form an mRNA, which in turn is translated to form protein. [Central dogma of molecular biology] tRNA (transfer RNA) − It brings amino acids during translation and reads the genetic code.