PRACTICE EXAM QUESTIONS 1 a DNA molecule is composed of 40 t

PRACTICE EXAM QUESTIONS 1. a DNA molecule is composed of 40% thymine, what percentage of gua- nine would be expected? B. 20% C, 30% D. 40% E. Need more information 2. During DNA replication, proteins unwind the DNA duplex, and separate the DNA strands. Those proteins include: A. DNA polymerase and ligase B. Single-stranded DNA binding protein and primase C. Helicase and DNA polymerase D. Helicase and single-stranded DNA binding protein 3. What determines the nucleotide sequence of the newly synthesized strand during DNA replication? A. the particular polymerase catalyzing the reaction TTP) in B. the relative amounts of the four nucleotide triphosphates (ATP, GTP, CTP and the cell C. the nucleotide sequence of the template strand D. the primase used in the reaction E. both a and d 4. The leading and the lagging strands differ in that A. the leading strand is synthesized in the same direction as the movement of the replica- tion fork, and the lagging strand is synthesized in the opposite direction. B. the leading strand is synthesized by adding nucleotides to the 3\' hydroxyl (OH) end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5\' phosphate (PO) end. C. the leading strand is synthesized continuously, whereas the lagging strand is synthe- sized in short fragments that are ultimately stitched together. D. both a and b E. both a and c

Solution

1. (A) is correct ( A+T)/(G+C) =1 is chargaff,s rule according to this if A is 40 % so T is also 40% 40 +40 =80

100 -80=20,

Hence G =20/2 =10%

Hence answer =10%