DNA Extraction from Kiwi (Requires one 50 minute class period)
Concept or conceptual understanding: DNA is the genetic material in organisms. We can extract DNA from tissue using a simple procedure.
Real world connections (Relevancy): DNA is frequently mentioned in popular culture in relation to forensics, genetic engineering, molecular research, and disease.
AZ standards: (include grade level and text):
Strand 1: Inquiry Process
Concept 2: Scientific Testing (Investigating and Modeling)
Design and conduct controlled investigations.
PO 1. Demonstrate safe behavior and appropriate procedures (e.g., use and care of technology, materials, organisms) in all science inquiry.
PO 4. Perform measurements using appropriate scientific tools (e.g., balances, microscopes, probes, micrometers).
PO 5. Keep a record of observations, notes, sketches, questions, and ideas using tools such as written and/or computer logs.
Incorporation of inquiry:
Students will use scientific processes and techniques to obtain data. Students will think critically about the data obtained and make connections to the real world.
Behavior objectives:
1) Students will predict what types of things have DNA.
2) Students will extract DNA from a fruit.
Prior knowledge necessary:
Students will require knowledge of the scientific process, lab safety protocol, and characteristics of organisms.
Identify possible student preconceptions:
High-tech equipment is necessary to remove DNA from organisms.
Materials:
1 500-mL or larger beaker, or 1 250-mL or larger flask
2 200-mL or larger graduated beakers
1 100-mL graduated cylinder
1 100-mL beaker
a kiwi fruit
knife and fork for cutting and mashing
thermometer
funnel
paper coffee filter to fit in the funnel
2 sauce pans for hot water baths
ice
cold water
hot water
50 mL chilled ethanol
2 g table salt
10 mL detergent
coffee stirrers
waxed paper or paper plate
access to a balance
hot plate (optional)
clock or watch
1 test tube for each group member
test tube rack
medicine dropper
tooth picks
Safety:
The hot plate and knife should be used with care.
Lesson Description:
Students will use a simple procedure to extract DNA from the cells of a kiwi fruit. The full procedure is available at http://www.exploratorium.edu/ti/human_body/dna.pdf.
Assessment:
1) Walk around the room and ask students questions to gauge their progress and comprehension.
2) After the activity, discuss the procedure to see if students understand the reasons for the various steps.
3) Discuss what other types of tissue could be used to obtain DNA. Would the procedure need to be altered? Why or why not?