Grades 6-8

Cell biology, scientific method

Teacher Resources

The DNA Extraction lab is an activity developed to help student explore the scientific method. Students will extract DNA from a plant to determine whether or not it’s fruit is biotic.

All living things are made of cells. Most cells contain deoxyribonucleic acid, or DNA, the blue print of all living things. In prokaryotes (single-celled organisms such as bacteria), the DNA is floating freely in the cytoplasm of the cell. In eukaryotes (multi-celled organisms), the DNA is enclosed within a nucleus. DNA contains the genetic code needed to synthesize proteins.

Learning Objectives

Students will be able to

  • Differentiate between biotic and abiotic factors
  • Identify the different components of a eukaryotic cell
  • Illustrate the different components of DNA
  • Extract DNA from a fruit
  • Outline the steps of the scientific method
Standards Alignments + Connections

TEKS Alignment

Middle School

  • 112.18.(b)(12)(A)
  • 112.19.(b)(12)(D)
  • 112.19.(b)(14)(C)

High School

  • BIOL.1A
  • BIOL.2A
  • BIOL.2F
  • BIOL.2H
  • BIOL.6A
  • BIOL.6B
  • BIOL.6H
  • BIOTECH130.403.10.D

Activities to Gather Evidence

Pre-Laboratory Engagement

Pre-Laboratory Engagement

Prepare Students for the use of the scientific method and various lab equipment (i.e., micropipettes, microcentrifuge tubes)

Pre-lab Questions

  • What are the steps of the scientific method?
  • How can you tell whether something is biotic or abiotic?
  • How will extracting DNA from fruit help us come to a conclusion in this experiment?
  • What is the basic structure of a nucleotide?

Activity

Download Student Handout

Laboratory Activity

Today, you will perform a DNA extraction to determine whether or not the fruit of a plant is biotic (i.e., whether it is living or produced by a living entity). In order to get to the DNA in eukaryotic cells, we must first get into the nucleus of the cell. In animal cells, the DNA is contained within two phospholipid bilayers, the nuclear envelope and the cellular membrane. Plant cells also contain a rigid structure called a cell wall, located just outside of the cellular membrane. In addition to these layers, both plant and animal cells contain organelles made of proteins and carbohydrate.

Post-Laboratory Extension

Post-Laboratory Extension

Post Lab Questions/Afterthoughts

  • What are the differences between DNA/RNA?
  • What effect does not having a control experiment have on your final results and conclusion?
Additional Resources

NIH
General information on DNA provided by the National Institutes of Health

Dolan DNA Learning Center
An animation of the 3-D structure of DNA