12.1

List the conclusions that Griffith and Avery drew from their experiments.

Griffith: Because the ability to cause disease was inherited by the offspring of the transformed bacteria, Griffith concluded that the transforming factor had to be a gene. Avery: DNA was the transforming factor. By observing bacterial transformation, Avery and other scientists discovered that the nucleic acid DNA stores and transmits genetic information from one generation of bacteria to the next.

What role did bacterial viruses play in identifying genetic material?

Hershey and Chase's experiment with bacteriophages confirmed Avery's results, convincing many scientists that DNA was the genetic material found in genes—not just in viruses and bacteria, but in all living cells.

Why did Hershey and Chase grow viruses in cultures that contained both radioactive phosphorus and radioactive sulfur? What might have happened if they had used only one radioactive substance?

1) Hershey and Chase grew viruses in cultured that contained both radioactive phosphorus and radioactive sulfur because proteins contain no phosphorus and DNA contains no suffer. Therefore, these radioactive could be used as markers. 2) If they had only used only one radioactive substance, they would have not been able to tell which molecules actually entered the bacteria

What are the three key roles of DNA?

1) storing information 2) copying information 3) Transmitting information

What clues did bacterial transformation yield about the gene?

By observing bacterial transformation, Avery and other scientists discovered that the nucleic acid DNA stores and transmits genetic information from one generation of bacteria to the next.

Why would the storage of genetic information in genes help explain why chromosomes are separated so carefully during mitosis?

Genes are transmitted from one generation to the next. This is why DNA molecules must be carefully sorted and passed along during cell division (meiosis). The loss of any DNA during meiosis might mean a loss of valuable genetic information from one generation to the next.

transformation

Process in which one strain of bacteria is changed by a gene or genes from another strain of bacteria

What is the role of DNA in heredity?

The DNA that makes up genes must be capable of storing, copying, and transmitting the genetic information in a cell.

bacteriophage

a kind of virus that infects bacteria

What conclusion did Hershey and Chase draw from their experiments?

the genetic material found in genes—not just in viruses and bacteria, but in all living cells

What was the experimental variable that Avery used when he repeated Griffith's work?

the heat-killed bacteria