1. A genetic mutation causes a disease when the the DNA encodes is altered
such that it no longer functions properly.
2 Errors during __ _ can cause genetic problems with the resulting germ cells.
3. Down syndrome is caused by three copies of chromosome 21, also known as
21.
4. A silent mutation is a change in the DNA that does not change the encoded
and has no phenotypic effect.

The hershey and chase experiments involved the preparation of two different types of radioactively labeled phage. which of the following best explains why two preparations were required? a. the bacteriophage used in the experiments was a t2 phage. b. it was necessary that each of the two phage components, dna and protein, be identifiable upon recovery at the end of the experiment. c. each scientist had his own method for labeling phage, so each conducted the same experiment using a different isotope. d. establishing the identity of the genetic material required observation of two phage generations.