Question

20. Which enzyme separates the strands of the DNA helix? A. DNA Polymerase E. Single Stranded Binding Proteins B. Ligase F. Primase C. Helicase G. Lagging Strand D. Topoisomerase H. Leading Strand 21. Which enzyme joins newly synthesized DNA fragments on the lagging strand? A. DNA Polymerase E. Single Stranded Binding Proteins B. Ligase F. Primase C. Helicase G. Lagging Strand D. Topoisomerase H. Leading Strand 22. In a PCR reaction, at which temperature do the two strands of DNA separate? A. 95°C B. 50-65°C C. 72°C D. 100°C 23. In a PCR reaction, at which temperature is DNA synthesis by the Taq polymerase initiated? A. 95°C B. 50-65°C C. 72°C D. 100°C 24. Which level of DNA packaging is visible during Metaphase of Mitosis and Meiosis? A. Nucleosome B. Solenoid C. Scaffold D. Chromosomes E. Double stranded DNA A. None of the above 25. To which region of a gene do transcription factors bind to initiate transcription? A. Promoter B. 5'UTR C. 3'UTR D. S' cap E. Poly-A tail 26. Which component of tRNA is complementary to the codons of mRNA? A. Amino acid attachment site B. DHU loop C. Peptidyl transferase D. Anticodon E. None of the above

Answer 1

20) The answer is Helicase.

explanation : DNA helicase is responsible for unwinding the DNA double helix. This happens as a result of breaking of the H bonds.

21) The answer is DNA ligase.

explanation : Okazaki fragments are several short fragments. These fragments are connected together into one molecule of DNA by the enzyme DNA ligase on the lagging strand.

22) The answer is 95°C.

explanation : in a polymerase chain reaction, the two strands separate at 95°C.

23) The answer is 72°C.

explanation : The best temperature at which the Taq polymerase forms the complementary strand is 72°C.

hope it helps.