In the dalmatians, there is a single gene that encodes for the protein that makes the coat pigments for the black fur spots. You are studying how this gene is regulated and isolated the DNA that encodes the gene as well as the processed mRNA molecule transcribed from the gene.
With the isolated DNA and mRNA molecules, you mix them in a test tube to hybridize them to one another, meaning that the DNA and mRNA molecules pair and align with one another based on sequence complementarity. Then, using a high-powered specialized microscope you take a picture of the mRNA paired with the DNA, which is shown below. In the image, the?DNA is black?and themRNA is blue.
(A) You notice that there are loops in the DNA strand that are not paired with the mRNA molecule. Based on what you know about the similarities and differences between the DNA sequence and processed mRNA sequence for a given gene,? explain what the loops in the DNA strand could be.
(B) Use what you know about transcription and mRNA processing to show on the diagram (label) ?which side of the mRNA is its 5? and which is its 3? end and?explainhow you can identify which end is which.
(C) A mutant spot gene was isolated that does not make pigment, and thus the animals have no spots. This mutant gene does make mRNA encoding the protein at similar levels as the wild type gene, but the mRNA molecules are slightly longer than usual. You repeat an experiment mixing and hybridizing DNA of the mutant gene with mRNA transcribed from the mutant gene and take a picture of it, shown below.
Based on your answers above and changes in the pattern of pairing between the wildtype DNA/mRNA molecules and the mutant DNA/mRNA molecule, suggest a possible explanation for (1) the nature of the mutation, (2) the effect it would have on the mRNA sequence, and (3) the effect it likely will have on the protein product.