TITLE WATER QSI*: THE DNA OF CRYPTOSPORIDIUM WATER QSI*: The DNA of CRYPTOSPORIDIUM [*Water Quality Science Investigation] Metropolitan Water District has a state‐of‐the‐
art water quality lab and conducts thousands of tests annually to ensure that the water quality is in compliance with local and federal guidelines. At the treatment plants, most of the harmful microorganisms can be eliminated with chlorine and/or ozone. However, some bacteria, such as cryptosporidium, can only be identified with special DNA tests. Cryptosporidium can be harmful to people with low immune systems, such as elderly people, infants, pregnant women and persons with the AIDS virus. Important to know: A genetic primer A gene is made up of DNA and has a specific and unique sequence of the four base parts. If your unique sequence matches one of the five patterns below, then the cryptosporidium parasite has contaminated your water supply. A & T ALWAYS BIND TOGETHER T – RED A = GREEN C & G ALWAYS BIND TOGETHER G = YELLOW C = ORANGE What you need: 1. Box of gumdrops (with large amounts red, green, yellow and orange) 2. 20 toothpicks 3. Blank sheet of paper for note taking 4. Instruction Sheet Get Started: 1. You will be creating five different strands of DNA. 2. Each strand will get 10 – 15 gumdrops and 10 – 15 toothpicks. Break each toothpick in half. 3. Select one of the strands and form the DNA sequence with the toothpicks and gumdrops. Continue the same process with the other four strands. Metropolitan Water District
bewaterwise.com STRAND 1: C – C – C – T – C – A –T – G – G – C—
C –A—A STRAND 2: T – A – C – T – T – T – G – G – G – T –
T—T—G STRAND 3: G – G – A – A – T – C – G – A – T – C—G—G—A STRAND 4: T – A – A – A – C – T – A – G – G – T—A—A—C STRAND 5: T—T—A—A—T—A—C—C—C—A –
G—G—C When you are done “building” your DNA strands, you must “match” the DNA strands. When two strands are perfect complements, they will “attach.” Every time “A” appears on one strand, “T” should appear on the other strand. Every time “G” appears on one strand, “C” should appear on the other strand. Find out which of the five strands had the “shock gene” or contaminated DNA by trying to match it up to the “shock gene” or contaminated cryptosporidium probe. Which strand is the contaminated water “sample?” By isolating or identifying the contaminated DNA, microbiologists can target it for eradication or killing the infectious organism. •
What did you learn? •
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The importance of DNA sequencing in identifying harmful and infectious organisms A genetic code for non‐infectious and infectious microorganisms allows water quality experts to identify and get rid of harmful bacteria. Making sure that harmful organisms are never present in our drinking water is of the highest priority for water agencies Metropolitan Water District
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