Identical twins occur when one egg is released and is fertilized by one sperm, and the pre-embryo later splits into two two eggs are released and are fertilized by the same sperm two eggs are released and are fertilized by two different sperm one egg is released and is fertilized by one sperm, and the fetus later splits into two

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.

What enzyme is most important for dna replication and why?

What function does the limb sever in each animal? how are the limb bones of the four animals similar? based on these similarities what can be inferred about the evolution of the four animals.