Name: ______Date: ______Period: ______

Biology activity: Modeling Recombinant DNA

Background vocabulary (use notes and /or glossary)

Plasmid:

Restriction enzyme:

Sticky end:

Recombinant DNA:

Materials

White paperClear tape (masking is okay, but harder to work with.)

ScissorsColored pencils—red and green (or any contrasting colors)

Procedure

  1. Cut two strips from the white piece of paper; one 2.5 cm wide by 10 cm long and the other 2.5 cm wide by about 28 cm long. Color the shorter piece greento represent a bacterial plasmid and the longer piece red, representing the new gene being added to the plasmid.
  1. Write the following sequence on the shorter piece of paper neatly. Evenly space the letters and make them large enough to fill the whole strip as shown.
  1. Use the short piece as a template and copy the sequence on each end of the longer piece. Match the size and spacing of the sequence on the short piece. There should be about 8 cm of empty space in the middle of the long piece when you are finished, representing the location of the gene to be introduced.
  1. Tape the ends of the short piece together with minimal overlap to create a ring. Do not tape the large piece into a ring.
  1. Cut the ring as the BamH1restriction enzyme would (a staircase cut between the GG and across to the next GG), leaving single-stranded sticky ends 4 bases long.
  1. Cut each sequence of the long strip in the same staggered manner as the ring, leaving a sticky end on each end of the long strip. Two small L-shaped pieces will be left over and can be discarded.
  1. If you have cut all pieces correctly, you should now be able to splice the red strip into the green strip. Tape the pieces together forming a large ring. Flatten and then staple the completed ring to this paper.

Fill in the table below with what each term is represented by in this activity.

Term / Represented in model by:
Plasmid
Target (“foreign”) gene
Restriction enzyme
Recombinant DNA

Analysis Questions

  1. In what way(s) does the paper model of a plasmid resemble a real bacterial plasmid?
  1. What is the importance of sticky ends for gene splicing?
  1. What are some critical characteristics for a scientist to consider when choosing a restriction enzyme (out of the 400 or so different restriction enzymes that are known) to successfully create recombinant DNA? (Hint: where should the enzyme cut and where should it not cut?)
  1. The majority of restriction enzymes known were not created by scientists; they were isolated from within the cells of living organisms, mostly bacteria. What might be the role of restriction enzymes in a living organism?
  1. Using your textbook or notes as reference, list at least one current use of recombinant DNA.