A genetic study performed on a 10-year-old boy reveals a single base substitution mutation involving a DNA segment that encodes a cellular protein, as shown in the image below. This mutation is most likely to affect which of the following processes?

Question

A genetic study performed on a 10-year-old boy reveals a single base substitution mutation involving a DNA segment that encodes a cellular protein, as shown in the image below.  This mutation is most likely to affect which of the following processes?

Quizplus · Accepted Answer

11ec160b_3777_9d57_9249_53641b45b8a8_MD0001_00 Genetic information flows from DNA to RNA to proteins. Most eukaryotic DNA sequences consist of coding exons, noncoding introns, and 2 promoter regions (the CAAT box and the TATA box). The CAAT box is located 70-80 bases upstream of the beginning (5' end) of the coding region, and the TATA box is located 25 bases upstream from the beginning of the coding region. Gene transcription begins when RNA polymerase II attaches to one of the promoter regions in a process that requires general transcription factors. A DNA enhancer region then binds activator proteins that associate with transcription factors and RNA polymerase II at the promoter, thereby increasing gene expression. Although promoters are not directly translated into protein, promoter mutations can cause abnormal gene expression by altering the ability of RNA polymerase II and transcription factors to bind. (Choice A) DNA methylation is part of the epigenetic code. This process is carried out by DNA methyltransferases and serves to silence the genes it affects. (Choice B) The folding of a formed polypeptide into its secondary and tertiary structures is entirely spontaneous and is determined by the amino acid sequence in the protein's primary structure. Heat shock proteins assist in the spontaneous refolding of proteins. (Choice C) Posttranscriptional RNA splicing is facilitated by small nuclear ribonucleoproteins (snRNPs) that remove introns from heterogeneous nuclear RNA (hnRNA) containing GU at the 5' splice site and AG at the 3' splice site. (Choice D) The TATA box only participates in the initiation of transcription. The addition of nucleotides to the forming RNA molecule (RNA elongation) continues until RNA polymerase II encounters a termination signal. (Choice F) In eukaryotes, translation initiation requires both ribosomal subunits (60S and 40S) with their associated rRNA, mRNA, initiation factors, initiator tRNA charged with methionine, and GTP. The assembled ribosome then recognizes the AUG start codon on mRNA to begin the process. Educational objective: The TATA box is a promoter region that binds transcription factors and RNA polymerase II during the initiation of transcription. It is located approximately 25 bases upstream from the beginning of the coding region. __________ References: RNA polymerase II transcription initiation: a structural view. (http://www.ncbi.nlm.nih.gov/pubmed/8990153)

A Genetic Study Performed on a 10-Year-Old Boy Reveals a Single