You are interested in the effects of mutations on the expression of a human protein-encoding gene expressed in skin cells. The gene has one intron that is 450 nucleotides long. After this intron is removed from the pre-mRNA, the mRNA transcript is 1100 nucleotides in length. Diploid somatic cells have two copies of this gene. Predict the size and amount of mRNA from the cytosol of skin cells, which were obtained from the following individuals:- **Individual 1**: Normal individual with no mutations in this gene.- **Individual 2**: Homozygous for a deletion that removes the -10 to -100 region of the gene that encodes this mRNA.- **Individual 3**: Heterozygous in which one gene is normal and the other gene has a deletion that removes the -10 to -100 region.- **Individual 4**: Homozygous for a five-nucleotide deletion in the intron that removes the GT sequence at the 5’ splice site.Explain your answers.

Functional part of a DNA that synthesizes any functional product in the form of mRNA and proteins is called a gene. This gene contains intervening sequences called introns which are to be removed prior to mRNA synthesis. This process is called splicing and it occurs in post transcriptional modification. 1. This mRNA would be of 1100 nucleotides. As there is no mutation this means that the intron would be removed properly and the mRNA would be synthesized normally. 2. If -10 to -100 nucleotides are removed in a homozygous condition this means removal occurs in both the genes. One of this strand would be a template strand that would synthesize mRNA. This region usually consists of a promoter so if the promoter is deleted, no RNA polymerase would be able to bind to the template strand DNA and thus their would be no transcription. Hence in this condition no synthesis of mRNA would take place. 3. In heterozygous condition one gene is normal and the other one suffers from a mutation of the removal of the promoter region located between -10 and minus hundred region. But as one gene is normal this means that mRNA would be synthesized but in lower quantities. 4. In a homozygous individual if there is a mutation which is responsible for the removal of GT sequence present in the 5' slice site of the introns, this means that intron would not be removed and the mRNA synthesized would be too large that is it will contain about 1100 + 450 nucleotides = 1550 nucleotides.