Lactase is an enzyme that digests lactose, the sugar in milk.
In most adults, the lactase gene produces very little lactase.
Some people have a genetic variant in the non-coding DNA in front of the lactase gene. These people continue to produce lactase as adults.
Describe the role of the non-coding DNA in front of a gene in protein synthesis.
Explain how this variant causes adults to continue to produce lactase.
The lactase produced by people with this variant has the same structure as the lactase produced by people without the variant.
Explain why.
Suggest one effect of this variant on the phenotype of an adult.
44 exam-style questions on Edexcel GCSE Biology 3.2 DNA and protein synthesis, covering 3.2.1 DNA structure as a polymer, 3.2.2 Genome and gene definitions, 3.2.3 Extracting DNA from fruit, 3.2.4 Base order determines protein shape, 3.2.5 Stages of protein synthesis, 3.2.6 Non-coding DNA variants affecting phenotype, and 3.2.7 Coding DNA variants affecting phenotype. Each one has a worked solution and a mark scheme showing where the marks go.