Question

3) With reference to nucleic acids (DNA/RNA), answer the following questions: 1) what are the coding and non-coding regions of pre-mRNA (non-functional mRNA) called (1/2 point each); ii) name the enzyme that splices out non-coding regions of pre- mRNA (1/2 point), iii) name the enzyme that joins coding regions to generate mature- mRNA (functional mRNA) (1/2 point); iv) name the major enzyme (1/2 point) involved in the "Polymerase Chain Reaction" and what is the major application of PCR (1/2 point); v) why t-RNA is called an adaptor molecule (1 point); vi) what is the percentage of rRNA in the cell (1/2 point); vii) what the section of DNA that regulates transcription is called (1/2 point)?

Answer 1

1) After transcription, the formed mRNA is called pre-mRNA. There are additional information present in pre-mRNA than in comparison to the final or mature mRNA. These additional informations are the RNA sequences known as INTRONS. Whereas, the information which is there in the final mRNA are the RNA sequences known as EXONS. Therefore, mature mRNA contains exon part only.

Exon contains both coding region (region that are translated into the final protein) and non-coding region representing the 5' and 3' untranslated region or sequences (UTRs). UTRs don't take part in translation but they maintains the stability of mRNA.

2) Spliceosome which is a large RNA protein complex made up of five small nuclear ribonucleoproteins.

3) RNA polymerase II

4) Taq DNA polymerase . The major application of polymerase chain reaction is to obtain a pure sample of gene.

5) tRNA is called an adaptor molecule because it attaches itself via initiation and elongation factors to the ribosome mRNA complex which facilitates the incorporation of the correct amino acid to the growing polypeptide chain by its specific anticodon to the mRNA codon.

6) 75%