occasionally three polar bodies are found clinging to the mature ovum. one came from an unequal division of the ovum, but from where did the other two arise?

How are viruses and bacteria different?

As a small change in a person's dna can cause a genetic disorder

The human genome project is devoted to mapping the general dna sequence of our species. this could lead to the development of new medicines, as well as the possibility of using gene therapy to treat certain diseases. however, there are some ethical issues surrounding the mapping of individual genomes. one concern is a) that your genes may change over time, making the project useless. b) that insurance companies could discriminate based on genetic make-up. c) that since this has never been done before, we should probably not do it now. d) that sequencing our individual genomes is so expensive, it is a counter-productive strategy.