Mutation: Thiamine Dimers A. what is a mutagen or cellular process that leads to this mutation? B. If the nucleotide excision repair pathway is not functional, is there another pathway or mechanism for preparing this mutation? if so, what is the pathway/mechanism? C. what is the consequence of this mutation if it is not repaired before DNA is replicated to make the next generation of cells?

Who Owns Your Genome? John Moore, an engineer working on the Alaska oil pipeline, was diagnosed in the mid-1970s with a rare and fatal form of cancer known as hairy cell leukemia. This disease causes overproduction of one type of white blood cell known as a T lymphocyte. Moore went to the UCLA Medical Center for treatment and was examined by Dr. David Golde, who recommended that Moores spleen be removed in an attempt to slow down or stop the cancer. For the next 8 years, John Moore returned to UCLA for checkups. Unknown to Moore, Dr. Golde and his research assistant applied for and received a patent on a cell line and products of that cell line derived from Moores spleen. The cell line, named Mo, produced a protein that stimulates the growth of two types of blood cells that are important in identifying and killing cancer cells. Arrangements were made with Genetics Institute, a small start-up company, and then Sandoz Pharmaceuticals, to develop the cell line and produce the growth-stimulating protein. Moore found out about the cell line and its related patents and filed suit to claim ownership of his cells and asked for a share of the profits derived from the sale of the cells or products from the cells. Eventually, the case went through three courts, and in July 1990n years after the case beganthe California Supreme Court ruled that patients such as John Moore do not have property rights over any cells or tissues removed from their bodies that are used later to develop drugs or other commercial products. This case was the first in the nation to establish a legal precedent for the commercial development and use of human tissue. The National Organ Transplant Act of 1984 prevents the sale of human organs. Current laws allow the sale of human tissues and cells but do not define ownership interests of donors. Questions originally raised in the Moore case remain largely unresolved in laws and public policy. These questions are being raised in many other cases as well. Who owns fetal and adult stem-cell lines established from donors, and who has ownership of and a commercial interest in diagnostic tests developed through cell and tissue donations by affected individuals? Who benefits from new genetic technologies based on molecules, cells, or tissues contributed by patients? Are these financial, medical, and ethical benefits being distributed fairly? What can be done to ensure that risks and benefits are distributed in an equitable manner? Gaps between technology, laws, and public policy developed with the advent of recombinant DNA technology in the 1970s, and in the intervening decades, those gaps have not been closed. These controversies are likely to continue as new developments in technology continue to outpace social consensus about their use. Do you think that donors or patients who provide cells and/or tissues should retain ownership of their body parts or should share in any financial benefits that might derive from their use in research or commercial applications?

Analyzing Cloned Sequences What kind of information can a DNA sequence provide to a researcher studying a disease-causing gene?

Discuss Concepts A forensic scientist obtained a small DNA sample from a crime scene. In order to examine the sample, he increased its quantity by cycling the sample through the polymerase chain reaction. He estimated that there were 50,000 copies of the DNA in his original sample. Derive a simple formula and calculate the number of copies he will have after15 cycles of the PCR.

Human Genome Replication Rate Assume DNA replication proceeds at a rate of 100 base pairs per second in human cells and origins of replication occur every 300 kbp. Assume also that human DNA polymerases are highly processive and only two molecules of DNA polymerase arc needed per replication fork. How long would it take to replicate the entire diploid human genome? How many molecules of DNA polymerase does each cell need to carry out this task?

Multiple Replication Forks in E. coli I Assuming DNA replication proceeds at a rate of 750 base pairs per second, calculate how long it will take to replicate the entire E. coli genome. Under optimal conditions, E. coli cells divide every 20 minutes. What is the minimal number of replication forks per E. coli chromosome in order to sustain such a rate of cell division?

The Enzymatic Activities of DNA Polymerase I (a) What are the respective roles of the 5 -exonudease and 3 -exonuclease activities of DNA polymerase I? (b) What might be a feature of an E. coli strain that lacked DNA polymerase I 3 -exonuclease activity?

What is the consequence of mutation of a mismatch repair enzyme? How will this affect the function of a gene?

Genetically Modified Foods The creation of transgenic crop plants using recombinant DNA methods involves the transfer of just one gene or a small number of genes to the plants, in contrast to classical breeding methods in which hundreds or even thousands of genes are transferred at once. Explain why this is true. If fewer genes are transferred during the creation of transgenic crops, why are some people afraid that they are dangerous?

Our bodies are not defenseless against mutagens that alter our genomic DNA sequences. What mechanisms are used to repair DNA?