IGEM Outreach:DNA Necklaces

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DNA Necklaces

  • Cornell iGEM 2011
  • Adapted from protocol developed by the Cornell Institute for Biology Teachers
  • Suitable for: all ages

Figure 1.1: DNA necklace: 1.5mL culture tube filled with wheat germ DNA on a string of yarn

Introduction

A major topic in modern biology research is DNA. The Human Genome Project, DNA fingerprinting, evolution studies, genetic diseases and tests, and bio-production are just a few applications that society has heard of for DNA. All of these techniques require a technician to remove DNA from a cell. (Remember, eukaryotes require an extra step—removing DNA from the nucleus.) In this activity, you will be the lab technician removing the DNA! Each step in the isolation process exists because of the characteristics of DNA.

Materials per person

  • Fresh raw wheat germ
  • Meat tenderizer
  • Hot water (shower temp)
  • Wooden skewer
  • Transfer pipette
  • Detergent in wash bottle (can be shared in a group)
  • Plastic tube, such as 10 mL culture tube
  • One 1.5mL microcentrifuge tube
  • Ice-cold 100% ethanol in wash bottle (leave on ice until needed, can be shared in a group)
  • Small cup or beaker
  • One string of yarn

Procedure

  1. Mix 50mL hot water and 1.5 g wheat germ in a small cup or beaker.
  2. Stir with wooden skewer.
  3. Add 2 squirts of detergent. (Detergent dissolves the lipid cell membranes.)
  4. Add 1.5g of meat tenderizer. (The tenderizer contains papain enzyme, which breaks down protein. This removes the histone proteins from DNA.)
  5. Stir for 2 minutes.
  6. Let the mixture sit for 2 minutes.
  7. Pour the liquid part of the solution into a plastic tube—leave most of the wheat germ in the cup. (The DNA should be in the solution.) Fill the tube halfway.
  8. Pour ice-cold ethanol down the inside edge of the tube you filled in step 7. Fill the tube almost to the top. (The ethanol helps the DNA come out of solution.)
    Figure 1.2: DNA precipitating from wheat germ in 10 mL plastic culture tube
  9. DNA strands will begin to precipitate and form! Suck up the DNA in the transfer pipette.
  10. Place the DNA in the 1.5mL microcentrifuge tube, and fill it with ethanol.
  11. String the yarn where the cap of the 1.5mL tube connects to its body and seal the cap on the tube.
  12. Enjoy your DNA necklace!

Experience

  • Step 1: water doesn't have to be hot in order for this activity to work, but it seems like warmer water produces better results. Cornell iGEM 2011
  • Step #11: consider hot-gluing the tube closed if you're helping young children. (They'll want to pop the cap off.) Cornell iGEM 2011


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