The exons and introns of a gene are shown below Alternative

The exons and introns of a gene are shown below. Alternative splicing of this gene produces four different mRNA transcripts. All four transcripts utilize the same start codon, which is the first codon in Exon 1. All four transcripts utilize the same stop codon, which is the last codon in Exon5. Based on the information provided in the figure below, predict the exon combinations of the four different transcripts and the length (number of amino acids) of each of the four proteins encoded by the four transcripts.

Solution

Each amino acid is encoded by three nucleotides. In last exon we need to remove 3 nt due to its stop codon nature which does not encode Amino acid.

1. 12345 : 603nt = 200 Amino acid length

2. 1235 : 553 nt = 184 Amino acid length

3. 1345: 563 nt = 187 Amino acid length

4. 1245: 393 nt = 130 Amino acid length