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Set Problem 3 Biology 313, Principles of Genetics Due Monday March 10, 2008 Name____________________________________________ 1) (3 pts) (1A) How are heterogeneous nuclear RNA (hnRNA) and messenger RNA (mRNA) related? hnRNA is the primary transcript that is processed into mRNA; hnRNA is pre-mRNA; hnRNA is processed into mRNA. (1 pt) (1B) Where in the cell would each type of RNA be found? hnRNA - nucleus mRNA nucleus &/or cytoplasm (1 pt) (1C) List the 3 major processing events required to make mRNA? Addition of 5' cap Addition of poly-A tail Splicing of introns and ligation of exons (1 pt) 2) (4.5 pts) The nontemplate strand of DNA has the following base sequence: 5'-CGCGGTTAGGTATAATTGACGCGTATGAGAGCTGTTCTGCTCCTTTTTAGTAAACCTTAATGAGCT-3' (2A) Underline in the above sequence an important cis-acting promoter element and provide its name. -10 region or Pribnow box; also accepted TATA or Goldberg-Hogness box. (0.5 pt) (2B) Find the open reading frame and write the corresponding mRNA sequence starting with the 5' codon. The first START codon (ATG) is shaded, which sets the reading frame. Every 3 bases are read until the 1st in-frame STOP codon (underlined) is reached. mRNA = (1 pt) AUG-AGA-GCU-GUU-CUG-CUC-CUU-UUU-AGU-AAA-CCU-UAA 1 (2C) Translate this mRNA into a sequence of amino acids. mRNA = protein = (1 pt) AUG-AGA-GCU-GUU-CUG-CUC-CUU-UUU-AGU-AAA-CCU-UAA MET-ARG-ALA-VAL-LEU-LEU-LEU-PHE-SER-LYS-PRO-STOP (2D) Assume a single C is inserted in the above mRNA sequence between the second and third base of the triplet codon for the first Phe. Write the new mRNA strand that results from this insertion and its translation product. What is the name for this type of change? mRNA = protein = (1 pt) AUG-AGA-GCU-GUU-CUG-CUC-CUU-UUC-UAG MET-ARG-ALA-VAL-LEU-LEU-LEU-PHE-STOP frameshift mutation (1 pt) 3) (2.5 pts) Below is a drawing which represents simultaneous transcription and translation in E. coli. Supply the correct response for the questions provided below. The direction of the RNA polymerase is given by the arrow. (0.5 pt each) (3A) The letter A is nearest the 5' or 3' end of the molecule? State which ____3'____ (3B) The letter B is nearest the 5' or 3' end of the molecule? State which. ___5'_____ (3C)The letter C is nearest the 5' or 3' end of the tRNA molecule? State which. ___3'_____ (3D) What is the "S" value for the large rRNA which is closest to the letter D? ___23S_____ (3E) Which terminus (N or C) of the growing polypeptide chain is nearest the letter E? ___N_____ 2 4) (3 pts) Below is a table showing the effect of different on media the growth of different tryptophan mutations in Salmonella typhimurium (+ = growth, - = no growth) Strain trp-8 trp-2 trp-3 trp-1 No Supplement - Medium Supplemented with IGP AA IN TRY + + + + + + + + + + (4A) Construct the biochemical pathway for the compounds IGP, AA, IN, and TRY based on these data. X >>>>> AA >>>>>>> IGP >>>>>>> IN >>>>>> TRY (1 pt) (4B) Place strains of bacteria (mutations) in the appropriate steps in the above pathway. trp-8 trp-2 trp-3 trp-1 X >>>>> AA >>>>>>> IGP >>>>>>> IN >>>>>> TRY (1 pt) (4C) In bacteria it is often possible to make partial diploid strains. Assume that a diploid strain was made containing the complete genomes of the trp-2 and trp-1 strains. Would this diploid strain be able to grow on the unsupplemented medium? Yes or no ? _YES_______ Explain your answer. The trp-2- mutant strain has a functional trp-1+ gene and the trp-1- strain has a functional trp-2+ gene. As a diploid, the 2 mutant genes would be complemented by the functional versions from each strain. (1 pt) 5) (1 pt) In a survey of 240,000 human births, six achondroplastic births were recorded to parents who were unaffected. Given that this form of dwarfism is caused by a fully penetrant, dominant, autosomal gene, what is the mutation rate? 6 = 6 = 1.25 x 10-5 (2) 240,000 480,000 The mutation rate = (the number of mutant gametes)/(the total number of gametes surveyed) (1 pt) 6) (1 pt) Describe how acridine dyes cause frameshift mutations. Acridine dyes intercalate between the bases of intact double stranded DNA. (1 pt) 3 7) (4 pts) The table below lists several genotypes associated with the lac operon in E. coli. For each genotype, indicate with a "+" or a "-" whether -galactosidase would be expected to be produced both on media with "no lactose" and on media "with lactose". -galactosidase production No Lactose With Lactose Genotype (7A) (7B) (7C) (7D) I+ O+ Z+/ F' I- O+ Z+ I- Oc Z+/ F'I- O+ ZIs Oc Z+/ F'I+ O+ Z+ I- O+ Z+/ F' I- O+ Z+ + + + + + + + (1 pt each genotype) I+ = wild type repressor I- = mutant repressor (unable to bind to the operator) Is = mutant repressor (insensitive to lactose) O+ = wild type operator Oc = constitutive operator (insensitive to repressor) 8) (1 pt) Given the diagram below, what type of control, positive or negative, is operating? Positive a regulatory protein binds and transcription occurs. (1 pt) 4 ... View Full Document

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