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Biomorph Challenge #6

DNA BLAST: The Movie

The Biomorphs reveal:

"You'll be surprised to learn who we really are. We have as much DNA as you do, but 3 million base pairs of ours differ 100% from yours."

What do you say? Extra Credit: Who or what are the Biomorphs?

Facts about Genomes. See 20 Facts about the Human Genome

  • There are 100 trillion (1012) cells in your body. Each cell contains DNA double helix totalling three billion (3 x 109) base pairs.
  • If unwound and linked together, the strands of DNA in one cell would stretch almost six feet but would be only 50 trillionths of an inch wide.
  • It would take about 9.5 years to read out loud (without stopping) the 3 billion bases in a person's genome sequence, if you read at a rate of 10 bases per second.
  • If all the DNA in your body was put end to end, it would reach to the sun and back over 600 times (100 trillion times six feet divided by 92 million miles).
  • Human DNA is 98 percent identical to chimpanzee DNA. Human DNA is 30% identical to E. coli DNA.
  • The average amount of genetic difference between any two humans is 0.2 %, or one in 500 bases. Chimpanzees differ by 0.8 %.

Useful Sites


Written assignment -- turn in PRINTOUT to professor

Note: It is HIGHLY RECOMMENDED that you paste these questions into Word and type your answers, presented in the order listed.

Biomorph Challenge #6

You are producing a film called DNA BLAST about a mad scientist who clones genes encoding toxins into E. coli bacteria to infect people, cause mass destruction, and take over the world. One such toxin gene is streptolysin, from a "flesh-eating" strain of Streptococcus.


1. Find the exact portion of Streptococcus DNA sequence that encodes the streptolysin protein. Paste the DNA gene sequence for streptolysin into Webcutter. Generate a restriction enzyme map showing all the enzyme cut sites in the sequence.


2. How can your mad scientist use PCR to make many copies of the DNA? Write a pair of two 20-base primer sequences that could be used to amplify (make copies of) the complete gene encoding streptolysin.


3. How could the scientist make an E. coli strain that would produce streptolysin? What additional kind of DNA would have to be used, and how? What kinds of enzymes would be needed?


4. To make sure the E. coli strain carries the right gene for streptolysin, the mad scientist has to analyze it as demonstrated in Plasmid tutorial. Complete one Plasmid exercise (intermediate level) with zero incorrect submissions, and turn in the printout.


5. Suppose the scientist wants to make other deadly E. coli strains with related but different toxins. One way to find such toxins in related bacteria is to paste the DNA sequence into BLAST. Based on what you find, what genes in which organisms might be promising?


6. Why is it easier to clone an E. coli strain than to clone a dinosaur? (Explain several reasons.)


7. In real life (not your film), would the E. coli strain containing the gene for streptolysin be likely to cause a deadly disease? Why or why not?


8. In the sequel to your film, your mad scientist decides to clone a human race producing an imaginary protein for "super powers." In order to insert the "super power" gene into human DNA, the scientist needs to cut human DNA with a restriction enzyme. For a restriction enzyme of sequence CAATTG, about how many cut sites would you expect in the entire genome? (Note: Use your calculator; no database needed.)