4. Linear chromosomes are protected from replicative senescence by a stretch of repetitive sequence called _____ and the enzyme that synthesizes it.
(A) telomere
(B) centromere
(C) promoter
(D) replication origin

30. EF-Tu is an important protein in cells whose function is to (A) properly fold proteins. (B) ensure proper ribosome assembly. (C) escort aminoacyl-tRNA to the ribosome. (D) protect rRNA from degradation by RNases. (E) stabilize mRNA within the ribosome. 

1. A Double-stand DNA can be peeled off by a _____ to become 2 single-strand DNAs. (A) DNA polymerase (B) helicase (C) RNA polymerase (D) ligase

2. DNA replication normally occurs at the _____ phase of cell cycle. (A) S (B) G1 (C) G2 (D) M

3. The catalytic center of a prokaryotic RNA polymerase is formed by _____(A)oa (B) Ba (C) yy (D) BB

5. The one recombinase employed in the bacteria homologous recombination is _____  (A) RecA (B) CRE recombinase (C) Flippase (D) Spo11

6. The transposition of _____ element involves a RNA encoded genome stage. (A) P-element (B) Tn10 (C) Tyl (D) Tn3

7. Mismatch repair of newly replicated DNA can be facilitated by _____ . (A) nicking of the parental strand in bacteria (B) nicking ofthe nascent strand in prokaryotes (C) methylation of the GATC in parental strand in eukaryotes (D) methylation ofthe GATC in parental strand in prokaryotes

8. A graduate student accidentally cloned a cDNA from an economically important animal whose genomic sequence has not been resolved. The sequence of this cDNA can be summarized as below: 5'-gegatagtataatatcggccaggATGccg..ggccgggtattctcatttTAAggcaggttctta-3 The start and stop codons are shown in bold capital. If he/she likes to amplify the coding region ofthis gene, which one of the following PCR primer sets will work for him/her? (A). 5'-cggccaggATGccg-3'/5'-ttctcatttTAAggcaggttctta-3 (B). 5'-gccggtcCTAcggc -3'/5'-ttctcatttTAAggcaggttctta-3 (C). 5'-cggccaggATGccg-3'/5'-taagaacctgccTTAaaatgagaa -3 (D). 5'-gccggtcCTAcggc -3'/ 5'-aaaATTccgtccaagaat -3

9. Attenuation of Trp operon is performed by (A) binding of ribosome to 5'-UTR (B) pairing of helices 3/4 of leader peptide (C) pairing of helices 2/3 of leader peptide (D) pairing of 5'-UTR and leader peptide

10. Okazaki fragments can be found at _____. (A) transating mRNA (B) transcribing rRNA (C) leading strand of replicating DNA(D) laggering strand of replicating DNA