Origins of Life from Chemical Inventory Overview
While there are many high school labs that are designed to help students understand the
process of natural selection, sexual selection and the significance of mutation on
evolution, few exist that allow students to investigate life’s chemical origins. This
inquiry-based lab series is designed to allow students to develop and utilize the same set
of lab skills while providing teachers with a foundation to incorporate pre-biotic
chemistry throughout both the Biology and the Chemistry curriculum.
Lab one: Synthesis of Adenine Lab
Overview: In the final lab of the series, students will conduct an experiment where they
create adenine, one of the nitrogenous bases found in DNA using chemicals that were
available to a primitive earth. This will demonstrate a plausible pre-biotic mechanism for
the chemical formation of adenine, one of the components of life’s most essential
macromolecules.
Biology Objectives: Students will understand that chemical processes can create the
macromolecules that comprise living things, and investigate how the building blocks of
DNA can be synthesized, using only chemicals readily available in primitive Earth.
Further, students can compare that the chemically generated adenine is identical in nature
to the biotic adenine extracted in the upcoming labs.
Biology Curriculum Link: Evolution Unit
Biology GPS Standards: SCSh2, SCSh3, SCSh4, SCSh5, SB5
Chemistry Objective: Students will perform a synthesis reaction where they will generate
adenine, using only chemicals readily available in primitive earth. Students will
understand that chemical processes are responsible for creating biotic material. This lab
can also be used in higher-level chemistry classes to provide an example or extension for
investigating Organic chemistry.
Chemistry Curriculum Link: Types of Chemical Reactions Unit/Organic Chemistry Unit
(Advanced Classes)
Chemistry GPS Standards: SCSh2, SCSh3, SCSh4, SCSh5, SC1,
Duration: This lab takes one class period, depending on the availability of an oven or
sand bath capable of reaching 180C or 220C, respectively.
Lab Two: Introduction to Thin Layer Chromatography (TLC)
Overview: This lab challenges students to identify the composition of unknown
nitrogenous bases. Students are introduced to TLC, which will be used in each of the
following labs in the series.
Biology Objective: Students will become familiar with the nitrogenous bases that are
found in DNA and proficient with spotting, developing and analyzing TLC plates.
Biology Curriculum Link: Chemistry/macromolecule unit
Biology GPS Standards: SCSh2, SCSh3, SCSh4, SCSh5, SB1,SB2
Chemistry Objective: Students will investigate one of the methods used for the separation
of mixtures, by becoming proficient with spotting, developing and analyzing TLC plates.
Chemistry Curriculum Link: Properties of Matter Unit
Chemistry GPS Standards: SCSh2, SCSh3, SCSh4, SCSh5, SC1
Duration: A 45-60 min class period is sufficient to run the lab. Additional class time may
be spent teaching students how to calculate the Rf values.
Lab Three and Four: DNA Extraction and Hydrolysis
Overview: This three-part lab takes a routine DNA extraction a step farther, by allowing
students to perform a DNA hydrolysis reaction in which one of its nitrogenous bases is
released. Students will use the TLC skills developed in the previous lab to determine the
identity of the unknown nitrogenous base.
Biology Objectives: Students will understand that DNA is a major molecule found in all
living things, and that the nitrogenous bases are a fundamental element of DNA. In
addition, students will understand that DNA is a chemical structure that can be broken
apart through hydrolysis reactions to release its individual components.
Biology Curriculum Link: DNA Structure/Function Unit
Biology GPS Standards: SCSh2, SCSh3, SCSh4, SCSh5, SB1, SB2
Chemistry Objective: Students will understand that DNA is a chemical structure and
perform a decomposition reaction through DNA hydrolysis to investigate one of the types
of chemical reactions.
Chemistry Curriculum Link: Types of Chemical Reactions Unit
Chemistry GPS Standards: SCSh2, SCSh3, SCSh4, SCSh5, SC1, SC2
Duration: This lab consists of three parts, each of which will take an entire class period.
It is not essential that Part 1 is performed consecutively with Parts 2 and 3; it can be
separated by up to two weeks. However, Part 2 and Part 3 must be performed on
consecutive days.
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