1. 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   Hint Half-n-half Clue   2. A repeating DNA sequence at the end of chromosomes that prevents them from losing base pair sequences at their ends and from fusing together is called :   A Telomere   A Telomerase   A replicon   None of the above.   Half-n-half Clue   3. What does transformation involve in Bacteria ?   the infection of cells by a phage DNA molecule   the creation of a strand of DNA from RNA   the creation of a strand of RNA from DNA   assimilation of external DNA into a cell   Half-n-half Clue   4. 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   Ligase   Helicase   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. 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   7. 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   Half-n-half Clue