8. DNA Replication

In this chapter, we focused on how DNA is organized at the chromosomal level. Along the way, we found many opportunities to consider the methods and reasoning by which much of this information was acquired. From the explanations given in the chapter, what answers would you propose to the following fundamental questions:How do we know that satellite DNA consists of repetitive sequences and has been derived from regions of the centromere?

There is a problem completing the replication of linear chromosomes at their ends.What is the function of telomerase, and how does it operate to synthesize telomeres?

There is a problem completing the replication of linear chromosomes at their ends.Describe the problem and identify why telomeres shorten in each replication cycle.

In 1994, telomerase activity was discovered in human cancer cell lines. Although telomerase is not active in most human adult cells, all cells do contain the genes for telomerase proteins and telomerase RNA. Since inappropriate activation of telomerase may contribute to cancer, why do you think the genes coding for this enzyme have been maintained in the human genome throughout evolution? Are there any types of human body cells where telomerase activation would be advantageous or even necessary? Explain.