Lab 10: Exploring GMOs

Transcription

1 Lab 10: Exploring GMOs

2 Notebook Lab Objectives To understand how genetic engineering supplements traditional methods of plant breeding to generate new traits in crop plants To understand how changing the genome of an organism can affect its ability to survive in different environments

3 Notebook Procedure Overview Part 1: Extraction of DNA from food samples Part 2: Set up PCR reactions Part 3: Electrophoresis of PCR products Part 4: Analysis of results

4 Background Information First genetically modified (GM) crop was released in the US in 1994 GM crops are controversial due to potential health and environmental risks Foreign genetic material from another plant or from other species Inserted gene codes for a protein that gives the plant an advantage over similar crop plants

5 Why genetically modify? Pest resistance Herbicide tolerance Delayed fruit ripening Improved fruit yield Increased nutrient content

6 GM Crops Arctic Apple resists browning Golden Rice biosynthesize beta carotene Bt Corn produces an endotoxin that is lethal to the European corn borer Vistive Gold Round Up resistant soy bean Papaya Resistant to papaya ring spot virus

7 How do you genetically modify a crop? Identify a trait (protein) that has the potential to improve a crop Isolate (clone) the gene that codes for the protein Engineer the gene so that the crop plant s cells will read it correctly and manufacture the protein of interest Introduce the engineered gene into the plant Backcross the GM crop into the highestyielding crop in the field

8

9 GMO-Associated Sequences 35S promoter of the cauliflower mosaic virus (CaMV 35S) Terminator of the nopaline synthase (NOS) gene of Agrobacterium tumefaciens Both sequences are present in ~85% of GM crops around the world

10 For or Against GMOs? Reduce use of herbicides and pesticides Preserve land Improve nutritional value of food Drought tolerance Salinity tolerance Longer shelf life Potential for superweeds or superbugs Possible allergens Not enough research Unpredictable changes to an ecosystem Antibiotic resistance

11 Recommended Foods to Test Processed food such as cheese-flavored puffed corn snacks (GM corn) Inexpensive meat products that contain soy fillers (GM soy) Nonorganic foods Papaya products AVOID fresh corn or soy

12 GM Food Labeling Legislation United States: Food is labeled GM Free if the food is < 5% GM European Union: Food is labeled GM if the food is > 1% GM Japan: Food is labeled GM if the food is > 5% GM

13 Test Foods Notebook

14 Part 1: Extraction of DNA from Food Samples Two microcentrifuge tubes label as follows: Non-GMO (with group initials) Test Food (with group initials) Notebook Prepare 50 µl of Non-GMO ground slurry and 50 µl of Test Food ground slurry Prepare the non-gmo sample first to avoid contamination!

15 Part 2: PCR Workstation Ice bath GMM: GMO Master Mix with primer (ice) PMM: Plant Master Mix with primer (ice) GMO +: GMO Positive Control DNA (ice) Test Food DNA Non-GMO Food Control DNA (oats) 6 PCR tubes and 6 PCR Adaptors 2-20 µl micropipette with tips

16 Notebook Part 2: Set Up PCR Reactions Plant primers (PMM) Used to determine if DNA was extracted from the plant material Targets a 455 bp region of a chloroplast gene GMO primers (GMM) Used to determine if the food contains GMOs Targets a 203 bp fragment of the CAMV 35S promoter and a 225 bp fragment of the NOS terminator

17 Notebook Part 2: Set Up PCR Reactions Number the tubes #1-6 Label clearly with group initials

18 Purpose of Each PCR Reaction Notebook

19 Part 3: Gel Electrophoresis of PCR Products First, add 10 µl of Orange G loading dye to each PCR sample (use a fresh tip each time) gently tap the tubes to mix Load 20 µl of each sample into the wells according to the chart provided Load 20 µl of the molecular weight ruler (MWR) into Lane 7 Notebook

20 Part 3: Gel Electrophoresis of PCR Products Use a 3 % gel for electrophoresis of PCR products Run at 100 volts for minutes Record a picture of your gel using UV light Notebook

21 Notebook Part 4: Analysis of Results Draw the results of gel electrophoresis into your lab notebook Be sure to label each well on the gel picture Label the base pair size for each fragment of the ladder (molecular weight ruler) Write a conclusion based on the results of your test food Discuss any sources of error that may have affected your results

22 Analysis of Results