Polymerase Chain Reaction Activity

(PCR)

Alexandra Romero

Gorton High School

Summer Research Program for Science Teachers

August 2006

Subject: Living Environment

Grade Level: 9^th and 10^th

Unit: Genetics, Biotechnology, lab skills

Objective: Students will be able to:

• Explain the importance and function of enzymes
• Describe the effect of temperature on enzymatic reactions
• Compare the process of DNA Replication and PCR
• List the steps involved in the PCR process
• Become familiar with the following terms:

denaturation, primers, replication, template, polymerase, PCR

Prior Knowledge: Teacher discussion on DNA replication, protein synthesis and the function and structure of the DNA molecule.

Introduction: To study genes scientists need a large quantity of DNA. PCR is a biotechnology technique that can produce many copies of a targeted DNA sequence. The process will replicate a small quantity of DNA in just a few hours. What are the ingredients to do a PCR? All you need is a targeted DNA strand, primers, enzymes and three different temperature chambers.

a)       The target DNA strand is heated (about 94ºC). DNA paired strands are separated and become single strands.

b)       Primers, short segments of DNA, are added and bound to the targeted single strands by complementary base pairing. This reaction occurs at a cooler temperature (about 50-65ºC).

c)       An enzyme, Taq polymerase, is added to the reaction at a higher temperature (about 72ºC). It binds at the primer site and copies the sequence of that strand. Within a short period of time it replicates the targeted DNA strand.

d)       This completes the first cycle and the above steps are repeated until you have many copies of the desired gene.

Materials:

Making a model of DNA handout

DNA review worksheet

Internet

Scissors

Colored pencils

Transparent tape

Poster board

Time: Three class periods-45 minutes

Procedure:

Day One – construct a DNA template

1. Have students construct a DNA template. They can decide how long they want the template to be (ex. 10 base pair or 15 base pair…) See DNA handout.

Day Two

1. Have each student complete a DNA review worksheet.
2. After completion of the worksheet students will view a PCR animation at http://www.dnai.org/b/index.html.
3. Assign students to read an article on PCR as a homework assignment. Have students generate questions from what they read.  You can select an article from the following web sites:

      http://sunsite.berkeley.edu/PCR/whatisPCR.html

      http://people.ku.edu/~jbrown/pcr.html

      http://www.swbic.org/links/6.1.1.2.php

      http://www.genome.gov/10000207

      http://www.uq.edu.au/vdu/PDU_PCR.htm

      http://lifesciences.asu.edu/resources/mamajis/pcr/pcr.html

Day Three – PCR Activity

1. Go over reading assignment. Explain the PCR process.
2. Now that the students are familiar with PCR, have them illustrate the process on a poster board. They can use the DNA template from the previous activity or draw it out. They should be able to illustrate the process so that anyone can look and understand the technique.
3. Further assessment - have students write how they would use the PCR process and explain why it is important.

New York State Science Standards

Standard 1 Key Idea 1-performance indicator 1.1b

                  Key Idea 2-performance indicator 2.2a

Standard 4 Key Idea 2-performance indicators 2.1a, 2.1b, 2.1c, 2.2c, 2.2d, 2.2e 

                  Key Idea 5- performance indicators 5.1f, 5.1g