The central dogma of molecular biology is key to understanding the relationship
between genotype and phenotype, although it remains a challenging concept to
teach and learn. We describe an activity sequence that engages high school
students directly in modeling the major processes of protein synthesis using the
major components of translation. Students use a simple system of codes to
generate paper chains, allowing them to learn why codons are three nucleotides
in length, the purpose of start and stop codons, the importance of the promoter
region, and how to use the genetic code. Furthermore, students actively derive
solutions to the problems that cells face during translation, make connections
between genotype and phenotype, and begin to recognize the results of mutations.
This introductory activity can be used as an interactive means to support
students as they learn the details of translation and molecular genetics.
Key Words: Translation; molecular genetics; genetic code; mutations.
Research has shown that students often have difficulty understanding molecular genetics. Connecting the concepts of genes with their
protein product and the protein product to phenotype has been
shown to be particularly challenging for them (Rotbain et al.,
2008; Reinagel et al., 2016). Reasons for such difficulty include that
genetics concepts extend across multiple organizational levels
(Marbach-Ad, 2001) and require students to understand that physical structures can “contain” information (Duncan & Reiser, 2007).
In order to understand the concepts associated with the central
dogma of molecular biology (DNA → RNA → protein) and eventually genetics, students first need to understand the relationship
between DNA, mRNA, and proteins, and subsequently that between
protein function and disease. It is critical they understand why the
genetic code uses three consecutive nucleotides for each codon,
why start and stop codons are required, the purpose of promoter
regions, and how genetic mutations affect phenotype, can cause disease, and form the basis for variation (Speth et al., 2014). However,
these concepts remain difficult for students to grasp.
To date, there have been a variety of suggestions for how to
effectively support students’ learning of molecular genetics. Many
of these interventions have utilized student-centered teaching strategies, whereby learners take a more active role in the learning process. For example, some activities have involved students using
computer animations to manipulate various molecular components
and processes (e.g., Marbach-Ad et al., 2008; Rotbain et al., 2008)
while others have engaged students in physically modeling the processes under study (e.g., Takemura & Kurabayashi, 2014; Marshall,
2017). Takemura and Kurabayashi (2014) involved students in a
role-playing activity with physical props to teach transcription
and translation, while Marshall (2017) engaged undergraduate
genetics students in a paper-modeling activity to simulate molecular processes. These authors have contended that students should
interact with the molecular entities as much as possible to best
learn the complex material. “Clearly interactivity, a factor known
to facilitate learning, can help overcome the difficulties of perception and comprehension” (Marbach-Ad et al., 2008, p. 287; Rotbain et al., 2008).
The activity sequence described here contributes to the growing
body of interactive instructional activities to help teach the central
dogma. It provides an inquiry-based, hands-on, tangible, dry-lab platform by which students can consider and learn the concepts of molecular biology such as codons, promoters, and the genetic code. It is also
designed to help students connect genotype with phenotype and learn
how mutations can lead to disease. This four-part activity sequence, in
its entirety, helps meet two high school NGSS life standards (NGSS
Lead States, 2013):
• HS-LS3-1. Ask questions to clarify relationships about the role
of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring.
• HS-LS3-2. Make and defend a claim based on evidence that
inheritable genetic variations may result from (1) new genetic
combinations through meiosis, (2) viable errors occurring during
replication, and/or (3) mutations caused by environmental factors.
The American Biology Teacher, Vol. 81, No. 3, pp. 202–209, ISSN 0002-7685, electronic ISSN 1938-4211. © 2019 National Association of Biology Teachers. All rights
reserved. Please direct all requests for permission to photocopy or reproduce article content through the University of California Press’s Reprints and Permissions web page,
www.ucpress.edu/journals.php?p=reprints. DOI: https://doi.org/10.1525/abt.2019.81.3.202.
Using Shapes & Codes to Teach
the Central Dogma of Molecular
Biology: A Hands-On Inquiry-Based
• MICHAEL I. DORRELL, JENNIFER E.