12th Class Biology Sample Paper Biology - Sample Paper-15

  • question_answer Differentiate between the following.
    (i) mRNA and tRNA
    (ii) Repetitive DNA and satellite DNA


    (i) Differences between mRNA and tRNA are as follows

    mRNA tRNA
    It is called messenger RNA and carries the codes for amino acid sequence. It is called transfer RNA and it carries amino acids to the site of protein synthesis.
    It is a long chain of bases with large molecular weight (25-200000 Dalton). It is clover leaf-like structure, with small molecular weight (25000 Dalton).
    It is synthesized by RNA polymerase-II. It is synthesized by RNA polymerase-III.
                (ii) Differences between repetitive DNA and satellite DNA are as follows
                Repetitive DNA Satellite DNA
    It is the non-coding DNA with multiple copies of identical sequences which may lie in tandem or interspersed. Refers to non-coding tandem repeat sequences.
    These can be few base pairs to hundreds or thousands of base pairs. These are generally short sequence repeated (upto 60 base pair long).
    In CsCL density gradient analysis, it appears as light bands. This appears as small dark bands.                                    


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