The red cone pigment is one of the light receptors in the vertebrate eye (an "opsin" protein), sensitive to red, yellow and orange light wavelengths. The red cone opsin protein is encoded by a gene named OPN1. Q1. The model below represents the structure of the OPN1 gene. The white boxes represent the gene exons. Interpret the structure of the gene: How many exons does this gene have? How many introns? Directly on the gene model, show and clearly label the positions of: (a) the promoter, (b) the +1 transcription start site (use a bent arrow to show that), (c) the location of the transcription termination sequence, (d) the site where transcription stops. Q2. Represent the products of transcription and of RNA processing: a) Beneath the model of the gene, draw a model of the primary mRNA transcript. Show how the mRNA lines up with the gene; pay attention where the molecule begins and where it ends. Label appropriately the ends of the primary transcript. b) Beneath the primary mRNA transcript, draw the mature mRNA. Show all post-transcriptional modifications, 5'- -3' Q3. The sequence below is a short segment of the noncoding (or, template) strand of the OPN1 gene. Based on the template strand provided, write the sequence of the coding strand, and label appropriately the ends of the molecule. 3'-ATCGGTACCGGGTCGTCACC-5' Q4. Write the sequence of the mRNA that corresponds to the gene segment above, and label the ends of the mRNA sequence appropriately.