Question

Differentiate between the followings:
(a) Repetitive DNA and Satellite DNA
(b) mRNA and tRNA
(c) Template strand and coding strand

Answer 1

Hint: DNA and RNA are the nucleic acids present in the cells. RNA is mostly single-stranded while DNA is a double-stranded molecule. Transcription copies the nucleotide sequence of one DNA strand into the RNA molecules.

Complete answer:
DNA is the genetic material present in the nucleus of the eukaryotic cells. A DNA sequence that is present multiple times in a haploid genome is called repetitive DNA.

(a) Repetitive DNA and Satellite DNA:

Repetitive DNA	Satellite DNA
It includes both highly repetitive andmiddle repetitive DNA.	It represents the highly repetitive DNA.
The middle repetitive DNA present in therRNA genes code for the ribosomal RNAs.	It does not code for any proteins or RNA.

(b) mRNA and tRNA:

mRNA (messenger RNA)	tRNA (transfer RNA)
It is a linear molecule.	It is a clover-shaped structure
It serves to carry the genetic informationstored in the DNA to the ribosomes whereit is translated into the amino acidsequence of polypeptide chains.	It carries the appropriate amino acids fromthe cell pool to the mRNA-ribosomecomplex to be incorporated into thegrowing polypeptide chains.

(c) Template strand and coding strand

Template strand	Coding strand
It is the strand of the DNA whosenucleotide sequence is copied into theRNA strands during transcription.	is the strand of DNA that does not serve asa template for transcription.
The sequence of the mRNA iscomplementary to the template strand.	It has the same nucleotide sequence as thatof the mRNA. However, mRNA has a uracilbase in the place of thymine present in thecoding strand.
It runs from 3’ to 5’.	It runs from 5’ to 3’.

Note: Some DNA sequences do not code for any proteins. Satellite DNA forms one or more additional peaks when the cellular DNA samples are centrifuged in a cesium chloride density gradient. It is mostly present in the centromere of chromosomes.