Name: _________________________________  SS#____________________________

 

Biol 325 Advanced Genetics Worksheet 1: Due 01/28/05

Remember:  The "For Credit" Problems are due in class.  No Late Worksheets will be accepted.  The recommended text problems are for your benefit only.

 

Recommended Text Problems:  Chap. 9: 1, 9-14, 17-19, 29, 32 web problem 1; Chap. 10: 19-22, 25; Chap. 11: 7-9; Chap. 13: 2, 4, 9, 11, 12, 13, 14, 29, 30, 32, 33

 

For Credit Problems:

 

  1. A single base pair (1 bp) of a DNA double helix weighs about 1 x 10-21g.  The human body contains approximately 0.5g of DNA. 
    1. How many nucleotide base pairs of DNA are in the human body? (0.5 pts.)

 

 

 

 

    1. If you assume that all the DNA in human cells is in the B-DNA form, how far would the DNA reach if stretched from end to end? (answer in kilometers) (0.5 pts.)

 

 

 

 

  1. Suppose a B-DNA molecule has 1 million base pairs.
    1. How many complete turns are there in this molecule? (1 pt.)

 

 

 

 

    1. If this same molecule were in the Z-DNA configuration, how many complete turns would it have? (1 pt.)

 

 

 

 

 

  1. A diploid human cell contains a total of approximately 6 billion base pairs of DNA.
    1. How many nucleosomes are present in such a cell? (Assume that the linker DNA encompasses 40bp) (1 pt.).

 

 

 

 

           

 

 

 

 

    1. How many histone proteins are complexed to this DNA? (1 pt.)

 

 

 

 

 

 

  1.  

a,  Which of the following two molecules of DNA has the lower melting temperature (Tm)? Why? (1 pt.)

           

 

 

b. Consider the Cot curve shown below.  What fractions of the DNA are unique sequences?  Highly repetitive units?  Middlle repetitive units? (1 pt.).

 

 

 

 

 

 

 

 

 

 

 

 

 

           

 

 

  1. A diagram of a linear chromosome is shown here.  The end of each strand is labeled A, B, C, and D.  Which ends cannot be replicated by DNA polymerase?  Why not? (1 pt.)

 

 

                       

 

 

  1. Some viruses contain RNA as their genetic material.  Certain RNA viruses can exist as a provirus in which the viral genetic material has been inserted into the chromosomal DNA of the host cell.  For this to happen, the viral RNA must be copied into a strand of DNA.  An enzyme called reverse transcriptase, encoded by the viral genome, copies the viral DNA into a complementary strand of DNA.  This strand of DNA is then used as a template by DNA polymerase to make a double stranded DNA molecule.  This double stranded DNA molecule is then inserted into the chromosomal DNA, where it may exist as a provirus for a long period of time. 
    1. How is the function of reverse transcriptase similar to the function of telomerase? (1 pt.)

 

 

 

 

 

    1. Unlike DNA polymerase, reverse transcriptase does not have a proofreading function.  How might this affect the proliferation of the virus? (1 pt.)