Introduction to DNA/RNA

1.   The Hershey-Chase experiment was a series of experiments conducted in 1953 by Alfred Hershey and Martha Chase that confirmed DNA’s preeminent role in inheritance. In their first experiment, bacteria were infected with T2 phage containing radioactive 32P-labeled DNA. In a second experiment, a separate batch of bacteria were infected with T2 phage containing radioactive 35S-labeled protein. Bacteria were then separated from the phage coats by blending followed by centrifugation. In the first experiment, most radioactivity was found in the infected bacteria, while in the second experiment most radioactivity was found in the phage coat. These experiments demonstrated that DNA is the genetic material of phage and that protein does not transmit genetic information. Could this same experiment be carried out with 35S and 14C? Explain? [2 marks]

2. If 15% of the DNA in a guinea pig cell is adenine, what percentage is cytosine? Explain your answer. [2 marks]


3.    Given your understanding of transcription and translation, fill in the blanks below and indicate the 5` and 
        3` ends of each nucleotide sequence. Again, assume no RNA processing occurs. [4 marks]

      Template strand of DNA:   _    _  T  _  _  _  _  _  _  _  _  _  _  _  _  _   _
   
      Nontemplate strand of DNA:    5`   C  A  T  A  A  T  G  T  A  C  A  T  G  C  C  3`
   
   mRNA:   _    _  A  _  _  _  U  _   _  _   _  _  _  _  _  _   _
    
   tRNA:   _   _  _  _ / _  _  _ / _  _  _  / _  _  _ / _  _  _ / _


4.   As the genetic material, DNA has two very important functions. List them. [2 marks]

5.    List two types of RNA and their roles [2 marks].