1. A mamalian cell typically has 1.2 meters (when completely outstretched) of double stranded DNA.The total time to duplicate the DNA is 5 hours. How many origins of replication are there if the rate of duplication is 16µmeters/min ?   250   15000   1   500   Hint Half-n-half Clue   2. The enzyme responsible for initiating the unwinding of double-stranded DNA (eliminating supercoiling) by nicking a single strand of the DNA molecule is :   Gyrase   Topoisomerase   Helicase   Ligase   Half-n-half Clue   3. The enzyme (made of proteins and RNA) that elongates chromosomes by adding TTAGGG sequences to the end of existing chromosomes is :   Telomerase   Exonuclease   Endonuclease   Amylase   Half-n-half Clue   4. An enzyme (used by all retroviruses) that transcribes genetic information of the virus from RNA into DNA, is :   Reverse transcriptase   RNA polymerase   Restriction nuclease   Methylase   Half-n-half Clue   5. An enzyme that recognizes and cuts DNA only at a particular sequence of nucleotides is often called :   Restriction endonuclease   RNA polymerase   Photolyase   DNA glycosylase   Half-n-half Clue   6. Because DNA polymerase III can only act from 5' to 3', continuous strand growth can be achieved only along one of the template strands (Leading strand) and strand growth along the other strand must occur discontinuously resulting in the production of a series of short sections of new DNA called :   Replicon fragments   Okazaki fragments   Klenow fragments   None of the above   Half-n-half Clue   7. The enzyme that replaces the nucleotides of the RNA primer with the appropriate DNA nucleotides is :   DNA Polymerase II   RNA Polymerase   DNA Ligase   DNA Gyrase   Half-n-half Clue