As a new graduate student, you are tasked with studying patients with Pitt - Hopkins syndrome, caused by mutations in the basic helix -loop-helix transcription factor TCF4. Further, you know that TCF4 is a homodimer and that proper function requires dimerization, in addition to subsequent DNA binding. To begin your study, you sequence the TCF4 gene in your three patient cohort and identify several sequence variants. The TCF4 coding region and sites of mutations are shown here (lines between codons indicate the correct reading frame). classify each of these mutations on the coding sequence (1 mark each); most likely impact on the resultant protein (1 mark each); and how each might affect ability of TCF4 to influence transcription (1 mark each). Patient 1 mutation: Patient 1 protein: Patient 1 functional effect: Patient 2 mutation: Patient 2 protein: Patient 2 functional effect: Patient 3 mutation: Patient 3 protein: Patient 3 functional effect: Patient #3 Patient #3 CTA LAGT GGT Wild type sequence: ATT CTA AGT GGT Mutant sequence: ATT GCT AAG TGG Dimerization domain DNA binding domain Exon #: 1 2 3 4 5 6 7 8 9 10 11 12 13 Patient #1 Patient #2 Wild type sequence: TTT TGT |CACGTT Mutant sequence: TTT TGG CACGTT TTTGG|CACGTT Wild type sequence: CGG CCCTGGCGG Mutant sequence: CGG|CCCTGACGG

You are studying a rare form of brain cancer where the newly-discovered genes BR and AIN are known to play a role in the development of this cancer. You perform a RNA-seq analysis on a patient with this form of cancer and compare the resulting expression histogram to a healthy patient. You conclude that AIN is heavily upregulated in the cancer patient and that the cancer patient's mRNA for BR retains one of that gene's introns in the RNA-seq results. Based on this information, BR is likely a(n) _________ and AIN is likely a(n) _________ . a. oncogene; tumor-suppressor gene b. tumor-suppressor gene; tumor-suppressor gene c. oncogene; oncogene d. tumor-suppressor gene; viral gene e. tumor-suppressor gene; oncogene

Shown below is a schematic drawing of a gene, with the transcription unit divided into numbered regions. The arrows (;) indicate transcription initiation sites, "D" indicates a splice donor site, "A" indicates a splice acceptor site, and "An" indicates a polyadenylation signal. Give all the possible fully processed mRNAs that could be produced from transcripts of this gene (you don't need to draw anything, just list the regions that would be included in each mRNA by number).

Describe what would happen to the lac operon in a low-lactose environment and in a high lactose environment. a) How will each of these environments affect gene expression? b) What would happen to the repressor in each case? c) How will each of these environments affect RNA polymerase?