DNA

The experiment should take approximately one hour to complete in full. It was initially created for 11–14 year-old learners but can be adapted when teaching genetics to other age groups. 

Use in a sequence of timetabled lessons, science clubs or as part of an activity day. 

Learning objectives

• Describe the role of DNA in living things.
• Describe the main processes involved in extracting DNA from plant cells.

Guidance notes

Introduce DNA using slides 3–5 of the PowerPoint. Ask the learners what they already know about DNA and link this to the inheritance of genes and why we have similarities in our appearance to our parents and siblings.

Demonstrate the method for extracting DNA from strawberries. Use the PowerPoint to introduce the demonstration and draw learners’ attention to the main steps in the method. 

Discuss why they think we use detergent, water and salt in the extraction solution. The learners will answer this question in their student workbooks later in the session. The detergent breaks down the fatty cell membrane to release the DNA, and the salt makes the strands of DNA bind together so they become visible.

In Activity 1, learners will use the same method used in the demonstration to extract DNA from kiwi fruit. They can work individually or in pairs depending on the availability of resources. If you have time, learners should follow the methods in the student workbook so they all do the practical twice – once without using pineapple juice and once using pineapple juice.

This resource was developed as part of the Chemistry for All project. The project was set up to explore and address barriers to participation in UK chemistry undergraduate study through a longitudinal project. Read the findings relevant to teachers, outreach providers, education policymakers and parents in the summary report, or download the full research report.

While learners are engaged in the practical, look for good examples to highlight at the start of the discussion. Use the hook to demonstrate pulling out stands of DNA from samples.

Give learners five minutes to answer the questions in their student workbook before going through the answers (available in the teacher notes and on the slides) as a class discussion.

Health and safety

Read our health and safety guidance and carry out a risk assessment before running any live practical.

The safety equipment suggested is in line with CLEAPSS requirements. For non-hazardous substances, wearing lab coats can help to protect clothes. The safety rules might be different where you live so it is worth checking local and school guidance.

Be aware of any allergies before carrying out the experiment.

Careers

The Chemistry for All project found that recognising the value and importance of chemistry, and appreciating how chemistry can lead to interesting and well-paid jobs strongly related to learners’ future aspirations. Discover how chemistry can prepare learners to pursue apprenticeships, university courses and vocational routes, or browse job profiles and try our career options game from A Future in Chemistry.

Introduce learners to Jason, a senior director of chip research at Oxford Nanopore Technologies by watching his video hob profile on slide 6. He works with other scientists to sequence DNA during viral outbreaks or during the discoveries of new species. Between the demonstration and Activity 1, highlight careers that use chemistry knowledge and other transferable skills, such as an executive editor in scientific publishing. Katie works with scientists to promote and publish their findings in leading scientific journals to make a difference around the world. 

Find more activities like this, plus longer projects suitable for off-timetable days, science lessons or clubs on our Outreach resources hub.