Final answer:
The student's question addresses a genetic variant (SNP) near the lactase gene that increases lactase production in Europeans, illustrating how single nucleotide changes can impact gene expression and protein production, with the lac operon serving as an example of gene regulation.
Step-by-step explanation:
The student's question refers to a specific single nucleotide polymorphism (SNP) near the lactase gene that is associated with lactase persistence in European populations. This SNP is located 13.9 kilobases (kb) upstream of the lactase gene, within intron 13 of the mini chromosome maintenance 6 (MCM6) gene which is a helicase. The presence of this SNP leads to a 2.8-fold increase in lactase production, allowing for the continued digestion of lactose into adulthood.
Such SNPs can significantly influence gene expression, and thus the production of specific proteins. The example provided about the IFNy gene illustrates another case where SNPs at a certain "address" in the gene can affect baseline production levels of the cytokine interferon gamma (IFNy). Specifically, the change of a nitrogen base at the +874 position can alter IFNy production.
Understanding genetic regulation and expression is crucial in molecular biology. For instance, regulatory genes and operator sequences control the transcription of structural genes, such as in the case of the lac operon in E. coli. The lac operon contains genes like lacZ, which encodes ß-galactosidase, crucial for lactose metabolism.