DNA PROBLEM SOLVING

Read the background information on about VNTR's. Then answer the questions from the autoradiograph below.
PART A Obtained from: www.pbs.org/wgbh/aso/resources/guide/earthappenact3.html
In this hypothetical paternity case, four autoradiographs show DNA "fingerprints" taken from three individuals: a mother, her child, and the child's alleged father. Each autoradiograph compares equivalent DNA segments from the three individuals. The two dark bands in each column represent one individual's DNA segments -- one inherited from that individual's biological mother and the other from the biological father. These segments differ in length from person to person; for this reason they are used as genetic markers. Here, each length is designated by a letter, A through O. The two letters associated with each segment indicate the individual's genotype.

Answer of the following on your own paper and turn it in to the teacher:

  1. Give the genotypes of the three individuals based on the genes shown in the autoradiograph.
  2. Which "letters" must the child have inherited from its mother?
  3. Which did the father "donate"?
  4. Why was the DNA run four times?
  5. Based on this information, could the alleged father actually be this child's father? Explain your reasoning.
B. Does the child (C) belong to father (F1),father (F2), or neither? Explain your reasoning. C. In the audioradiograph to the right determine which sets of twins are identical and which are fraternal based on their DNA.

D. A mother gives birth to a set of twins and the husband (dad 1) suspects that the babies are not his. DNA samples run on two different alleles are shown above. From the information given answer the following questions;

  1. Are the twins identical or fraternal? How do you know?
  2. Who is the father of twin 1? Discuss your reasoning.
  3. Who is the father of twin 2? Discuss your reasoning.
  4. How can this situation be true?
  5. How many similarities will these twins share? Discuss your reasoning.

Click here for a picture of the twins. Note anything unusual??

E. Mitochondrial DNA

  1. What is this diagram showing?
  2. How is mitochondrial DNA different from nucleic?
  3. How is this typing performed?
  4. Give the pros and cons of this typing.
  5. Under what condition would mitochondrial testing be better than nucleic?

Useful links:

FBI
Mitotyping Technologies (go to mtDNA background)

Of the 3 billion base pairs in the human DNA, 16,569 are in the mitochondria. The other 99.9995% of the human DNA is nuclear and is found in the chromosomes.

F. THE ROMANOVs--Summary it up!!

Summarize the Romanov story. This will involve reading all sections of:

  1. the Romanov family
  2. The Mystery of Anna Anderson
  3. Science Solves a Mystery

Your summary should include the story of the Romanovs, the involvement of Anna Anderson, and the conclusions with explanation of how DNA testing was used.

(Hint: When on the DNA Interactive site, click on applications, then Recovering the Romanovs. Read all sections.)

G. EXTRA! EXTRA! READ ALL ABOUT IT!!

  1. Who was one of the first to be exonerated using mitochondrial DNA?
    (Look up first mitochondial DNA on www.google.com and print the first page of the article from which you got your information.)
  2. How does Jesse James fit into a discussion of mitochondrial DNA?

US News
Michael Finnegan

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