26. Nucleic Acids and Protein Synthesis

Tuftsin is an immunostimulator tetrapeptide having the following sequence:

                                   Thr–Lys–Pro–Arg

Write a possible sequence for the gene (Informational & template strand) that codes for this tetrapeptide.

What amino acid sequence is coded for by the mRNA base sequence CUC-AUU-CCA-UGC-GAC-GUA?

Gln-His-Pro-Gly is the sequence of a molecule known as progenitor thyrotropin-releasing hormone (pro-TRH). If we were searching for pro-TRH genes, we would need to know what sequence of bases in DNA we should be looking for. Use the following boxes to indicate answers to parts (a)–(d).

a. What RNA sequence could code for these four amino acids?

What is an anticodon, and on what kind of nucleic acid is it found?

What tetrapeptide is synthesized from the informational DNA sequence G-T-C-A-G-T-A-C-G-T-T-A?

The codons UGA, UAA, and UAG do not code for amino acids. What is their role as codons in mRNA?

What are the three steps of translation?

The following sequence is a portion of the DNA template strand: TGT GGG GTT ATT

b. What are the anticodons of the tRNAs?

The following is a segment of the DNA template that codes for human insulin: TTT GTG AAC CAA CAC CTG 

b. Write the three-letter and one-letter abbreviations for this corresponding peptide segment.

Consider the following segment of mRNA produced by the normal order of DNA nucleotides:

ACA UCA CGG GUA

e. What is the amino acid order if an insertion mutation adds a G to the beginning of the mRNA segment?

Consider the following segment of mRNA produced by the normal order of DNA nucleotides:

ACA UCA CGG GUA

f. What is the amino acid order if a deletion mutation removes the A at the beginning of the mRNA segment?

A point mutation in the mRNA for an enzyme results in the replacement of leucine with alanine in the resulting enzyme molecule. Why does this change in amino acids have little effect on the biological activity of the enzyme?

A specific virus contains RNA as its genetic material.

a. Why would reverse transcription be used in the life cycle of this type of virus?

A specific virus contains RNA as its genetic material.

b. What is the name of this type of virus?

How do protease inhibitors disrupt the life cycle of the HIV virus?