24. Primers are used in both PCR and in DNA sequencing. What is the purpose of the primers? (A) to separate the DNA template strands. (B) to provide a 3'- OH for DNA polymerase to build a new DNA strand. (C) to terminate synthesis of the growing DNA strand. (D) to separate various-sized DNA products. (E) to add nucleotides to a growing DNA strand.

20. Type 1 fucosidosis is a rare buman disease. Patients cannot hydrolyze the disaccharide fucose, and as a result have severe neurological decline and die by age 6. The disease is due to a defect in the gene that encodes the lysosomal enzyme that breaks down fucose (α-1-fucosidase), and is inherited in an autosomal recessive manner. Jane and John have a child who has Type 1 fucosidosis. What is the probability that their next two children will all NOT have the disease? (A) None (all of their children will have the disease) (B) 1/2 (C) 3/4 (D) 1/8 (E) 9/16

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