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 that accomplishes the unwinding of the original double stranded DNA molecule, once supercoiling has been eliminated, by breaking the hydrogen bonds that hold the two strands together is :   Topoisomerase   Helicase   DNA Polymerase II   Primase   Half-n-half Clue   3. The enzyme that (during replication) proceeds along one of the strands of a DNA molecule adding deoxy-nucleotide-triphosphates to hydrogen bond with their appropriate complementary dNTP on the other single strand and to form a covalent phosphodiester bond with the previous nucleotide of the same strand is called :   DNA Polymerase III   Primase   DNA Polymerase I   DNA Polymerase II   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 :   Topoisomerase   Helicase   Gyrase   Ligase   Half-n-half Clue   5. In 1940, Nobel Laureate Barbara McClintock discovered sequences of DNA that can move around to different positions within the genome of a single cell and cause mutations. These sequences (first observed in maize) are called :   Transposons   inverted repeats   direct repeats   sticky ends   Half-n-half Clue   6. DNA Polymerase III is actually an aggregate of several different protein subunits. So it is often called a :   Holoenzyme   Primeosome   replisome   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