LCT and MCM6 are found on the same human chromosome. Suggest differences between gene LCT and gene MCM6, other than their being at different positions on the same chromosome.
With reference to lactase synthesis, Explain the relationship between: a transcribed strand and a primary transcript; a primary transcript and messenger RNA (mRNA).
A mutation in a regulatory intron of MCM6 allows lactase synthesis to continue. This is known as lactase persistence. In this mutation, the number of nucleotides in the intron remains the same, but one nucleotide is different from the original nucleotide. State the type of mutation that causes lactase persistence.
Fig. 3.1 summarises the reaction catalysed by lactase. Draw the ring structure of $\alpha$-glucose in the box provided so that Fig. 3.1 is complete.
Lactase supplements (tablets) can be taken before milk or milk-based products are eaten to prevent symptoms of lactose intolerance. A student compared the activity of two different concentrations of a lactase supplement using an artificial substrate, ONPG, instead of lactose. A solution of ONPG is colourless, but hydrolysis of ONPG by lactase releases a coloured product. The student planned to monitor the progress of the reaction for each concentration of lactase using a colorimeter. Explain why the student chose to use a colorimeter to follow the progress of the reaction for each concentration of lactase.
Milk lactose can be hydrolysed either by immobilised lactase or by free lactase solution. This produces milk and milk products with no lactose, making them suitable for lactose-intolerant people. Scientists carried out an investigation to compare the activity of lactase immobilised in very small magnetic beads (magnetic microspheres) with free lactase, at different temperatures and at different pH values. Fig. 3.2 shows the activity of immobilised lactase and the activity of free lactase at 5 different temperatures. Fig. 3.3 shows the activity of immobilised lactase and the activity of free lactase at 8 different pH values.