In humans the LCT gene encodes the enzyme lactase which is necessary for metabol
ID: 213848 • Letter: I
Question
In humans the LCT gene encodes the enzyme lactase which is necessary for metabolizing the disaccharide lactose. Lactase catalyzes the first step in the metabolism of lactose by breaking lactose into the monosaccharides glucose and galactose. Glucose and galactose are then broken down to form ATP by cellular respiration (more on this later in the Carbohydrates Module). To study LCT gene expression, you sequence a 1 kilobase region surrounding the transcription start site. Which of the following would you expect to find? (check all that are correct) an A block and a C block for TFIID to bind the -10 and-35 sequences for TFIID to bind binding sites for ancillary transcription factors to bind AAUAAA for CPSF to bind a TATA box to bind TFIID an operator sequence for lac repressor to bind Many adults become lactose intolerant later in life, which is thought to be due to changes in transcription of the LCT ene. With this hypothesis, you sequence the LCT gene and more of its surrounding genomic sequence in several actose tolerant and lactose intolerant individuals. You find a number of single basepair mutations only in the lactose ntolerant individuals. These mutations are not in the LCT gene, but are located 10-20 kilobases upstream of the ene in the introns of the MCM6 gene (pictured below as bolded nucleotides with slash marks, example- G/A). MCM6 gene LCT geneExplanation / Answer
Answer: Options B, C and E are correct.
-10 and -35 sequence elements can be found. But they are not bound by TFIID
Ancillary transcription factors can bind to the upstream region of the transcription start site.
TFIID binds to the TATA box located upstream to the transcription start site.