DNA and Bioethics HERSHEY AND CHASE Virus made

DNA and Bioethics

HERSHEY AND CHASE • Virus -made of DNA and protein • The experiments • a virus with either radioactive DNA or radioactive protein were used to infect bacteria • Either the radioactive proteins or radioactive DNA would be transferred to the bacteria • Identifying which one is transferred would identify the genetic material. • Only the radioactively labeled DNA was transferred.

DNA STRUCTURE • Composed of nucleotides • nitrogen containing base, a five -carbon sugar (deoxyribose), and a phosphate group. • Four possible bases: adenine (A), guanine (G), cytosine (C), or thymine (T)

CHARGAFF’S RULES 1 st: The composition of DNA varied from one species to another. This molecular diversity added evidence that DNA could be the genetic material. 2 nd: the amount of one base always approximately equals the amount of a particular second base. Example: guanines equals the number of cytosines

BASE PAIRING • Purines- Adenine and guanine • two ring structures. • Pyrimidines- Thymine and cytosine • one ring structure. • A purine always combines with a pyrimidine in the DNA double helix!

THE DOUBLE HELIX • Rosalind Franklin • Worked with DNA fibers. • Maurice Wilkins, used x-ray diffraction photographic techniques to analyze the structure of DNA. • In February 1953, Francis Crick and James D. Watson had started to build a model of DNA. • indirectly obtained Franklin's data which had crucial information Crick and Watson then published their double helical model of DNA! (They get most of the credit)

Watson and Crick

RNA DNA Single Stranded Double Stranded Specific Base Uracil Thymine Sugar Ribose Deoxyribose Size Relatively small Big (chromosomes) Location Moves to cytoplasm Stays in Nucleus Types m. RNA, t. RNA, r. RNA DNA

The completion of The Human Genome Project! WOW!!!!! � However, is knowing all of our DNA a good thing?

� Imagine someone analyzes part of your DNA. Who controls that information? � What if your health insurance company found out you were predisposed to develop a devastating genetic disease. Might they decide to cancel your insurance? Privacy issues concerning genetic information is an important issue in this day and age. � ELSI stands for Ethical, Legal and Social Issues.

Who owns genetically modified organisms such as bacteria? � Can such organisms be patented like inventions? � Are genetically modified foods safe to eat? Might they have unknown harmful effects on the people who consume them? � Are genetically engineered crops safe for the environment? � Might they harm other organisms or even entire ecosystems? � Who controls a person’s genetic information? What safeguards ensure that the information is kept private? � How far should we go to ensure that children are free of mutations? Should a pregnancy be ended if the fetus has a mutation for a serious genetic disorder? �

A strain of corn has been created with a gene that encodes a natural pesticide. On the positive side, the transgenic corn is not eaten by insects, so there is more corn for people to eat. The corn also doesn’t need to be sprayed with chemical pesticides, which can harm people and other living things. On the negative side, the transgenic corn has been shown to cross-pollinate nearby milkweed plants. Offspring of the cross-pollinated milkweed plants are now known to be toxic to monarch butterfly caterpillars that depend on them for food. Scientists are concerned that this may threaten the monarch species as well as other species that normally eat monarchs