The diagram shows a strand of mRNA undergoing splicing - Scottish Highers Human Biology - Question 4 - 2022

To determine the number of amino acids coded by the mature mRNA transcript, we first need to calculate the number of bases in the mature transcript. The total number of bases in the primary transcript is 3150, and we subtract the bases removed by splicing (600) to get:

$3150 - 600 = 2550 \text{ bases in the mature transcript.}$

Since each amino acid is encoded by a codon that consists of 3 bases, we divide the total number of bases by 3:

$\frac{2550}{3} = 850 \text{ amino acids.}$

However, we need to exclude 1 start and 1 stop codon, which do not code for amino acids. Therefore, the final count is:

$850 - 2 = 848 \text{ amino acids.}$

The process is called alternative RNA splicing.

Alternative RNA splicing allows for different combinations of exons to be included in the mature mRNA transcript. By retaining certain exons and excluding others, the same gene can produce multiple mRNA variants. Each variant can then be translated into a distinct protein with different functions or properties.

The mutation has resulted in one of the introns being retained in the mature mRNA transcript. This means that not all introns have been removed, which could potentially affect the mRNA's ability to be correctly translated.

As a result of the retained intron, the protein may not fold properly. This is because the sequence of amino acids would be altered due to the inclusion of non-coding regions, which can disrupt the overall shape and function of the protein.