Question

A segment of a double-stranded DNA molecule is shown below. The start of a gene is indicated as the +1 base pair: + 1 5'TATATTTTCTATATGCACATTTGCAAGTAA 3'(strand A) 3'ATATAAAAGATATACGTGTAAACGTTCATT 5'(strand B) Uparrow (A) If RNA polymerase moves along this DNA from left to right, indicate the position of the promoter region on this DNA and indicate which strand is the template strand (B) Write the complete mRNA that would be transcribed from the gene above, again being sure to label the 5' and 3 ends, and noting any modifications that would be added to a mature mRNA molecule in a EUKARYOTE. (C) Label the following on your mRNA above: start codon, stop codon, 5'UTR, 3' UTR. (D) Using the genetic code at the end of this exam, determine the sequence of the polypeptide that would be translated from the mRNA you determined in (B) (E) Note the base pair in the DNA molecule at the beginning of this problem that is labeled with an arrow. For the following changes in the DNA at that base pair, indicate the new codon that would be transcribed and then translated, and the name of the type of mutation.

Answer 1

A.

TATATTTTCTATATATGCACATTTGCAAGTAA Promoter region

Strand B is the template strand

B.

5' UAUAUUUUCUAUAUAUGCACAUUUGCAAGUAA 3'

C.

Start codon Stop codon 5' UAUAUUUUCUAUAUAUGCACAUUUGCAAGUAA 3' 5' UTR

D. Met His Iso Cys Lys Stop

E.

Type of base change New codon New amino acid/translatedName of mutation type codon Transition Tranversion #1 Transversion #2 UGU UGA UGG Cysteine Stop codorn Tryptophan Silent Mutation Non-Sense mutation Mis-Sense Mutation Insertion of aTA base pair at the beginning of the codon UAU Tyrosine Mis-Sense Mutation