Question

1. Amino acids have both a three letter, and a one letter code, for example the amino acid Glycine is “Gly” or “G.” There are 20 single letter codes for amino acids, which is almost an entire alphabet.

(skip any letters without a corresponding amino acid) it would make.

A. For example:  “Ryan Smith”, would be: “Arginine, Tyrosine, Alanine, Asparagine, Serine, Methionine, Isoleucine, Threonine, Histidine”

B. Take this sequence of amino acids, and write out a sequence of RNA that could code for it.

C. Calculate the number of A, G, C and U’s in your RNA sequence.

D. Take the sequence of RNA from your answer in C and write it as a double stranded molecule of DNA. You can add a start and stop codon if you want but not required for this problem

E. Calculate the number of hydrogen bonds holding your two DNA strands together.

F. Using the DNA sequence from Part D, make a new nucleotide sequence, and if one or more amino acids are changed, please provide the new amino acid sequence in the one letter code  

i. nonsense mutation

ii. missense mutation

iii. silent mutation

Answer 1

1. B. CGU-UAU-GCU-AAU-UCU-AUG-AUU-ACU-CAU

C. A-7, C-5, G-3, U-12

D. 5' TAC-TCA-TTA-GTA-TCT-TAA-TCG-TAT-TGC 3'

3' ATG-AGT-AAT-CAT-AGA-ATT-AGC-ATA-ACG 5'

E. 19 X 2 for GC + 8 X 3 for AT = 62

F. For nonsense mutation, 5' TAC-TCA-TTA-GTA-TCT-TAA-TCG-TAT-TGC 3' if the thiamine in bold is replaced by A the corresponding RNA will yield CGU-UAA-GCU-AAU-UCU-AUG-AUU-ACU-CAU. Here the protein sequence will terminate due to UAA stop codon making only one amino acid Arginine (R).

For missense mutation, 5' TAC-TCA-TTA-GTA-TCT-TAA-TCG-TAT-TGC 3' if the thiamine in bold is replaced by G the corresponding RNA will yield CGU-UAU-GCU-AAU-UCU-AUG-AUU-ACU-CAG. Here the protein sequence changes to replace histidine with glutamine. Protein sequence is thus - RYAN SMITQ.

For silent mutation, 5' TAC-TCA-TTA-GTA-TCT-TAA-TCG-TAT-TGC 3' if the thiamine in bold is replaced by C the corresponding RNA will yield CGU-UAA-GCU-AAU-UCU-AUG-AUU-ACU-CAC. Here, the protein sequence will remain the same, as the altered codon also codes for the same amino acid histidine. Protein sequence is thus - RYAN SMITH.