16. Nucleotides are added at an approximate rate of 50 nucleotides per second in eukaryotic cells. The human genome contains 6.4 billion nucleotides (3.2 billion base pairs), which must be copied. Calculate the length of time in days that it would take to copy the human genome. Show all calculations including units. 17. Why do you think multiple replication bubbles form during the process of DNA replication? DNA Repair Begin the process of DNA replication by feeding the strands of the constructed DNA into the helicase enzyme on the replication mat. Be sure to position the 5' and 3' ends of the DNA appropriately as you place the DNA on the mat. Continue feeding the DNA through the enzyme until you have 11 bases emerging from the helicase. Notice that helicase moves into the replication fork, not away from it. 18. What does the helicase appear to be doing? 19. Identify which type of bond is broken. 20. Why is the helicase able to break these bonds