Transcription and translation are stages in the synthesis of proteins - Edexcel - GCSE Biology - Question 9 - 2019 - Paper 1

A mutation in the non-coding region of the DNA may lead to the alteration of regulatory sequences such as enhancers or silencers. These elements are crucial for the binding of transcription factors and the initiation of transcription. If the mutation disrupts these sequences, it can either enhance or inhibit the binding of RNA polymerase and other required proteins, thereby preventing the transcription of the gene.

The mutation in allele 2 results in one of the codons being changed from GAG to GAG, which does not alter the amino acid sequence due to the redundancy of the genetic code. However, if the mutation were to change a codon that specifies an amino acid, it could lead to the incorporation of a different amino acid during translation, potentially affecting the protein's structure and function. For instance, if a critical amino acid was altered, it could lead to a dysfunctional protein, impacting its biological role.

Blood group is determined by the alleles inherited from the parents. The possible alleles for blood group are A (IA), B (IB), and O (i). The mother is blood group A and can have genotypes IAIA or IAi, while the father is blood group B and can have genotypes IBIB or IBi. The child is blood group O (genotype ii), which means they must inherit one O allele from each parent. Therefore, both parents must carry the O allele. Using a Punnett square, we can show the possible combinations:

From the Punnett square above, the combinations show that it is possible for the child to be blood group O only if both parents carry the O allele, confirming the child's blood group as O.