Reasoning in Molecular Genetics: From a Cognitive Model to Instructional Design

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Reasoning in Molecular Genetics From a Cognitive
Model to Instructional Design

• Ravit Golan Duncan
• Northwestern University

Supported by the Center for Curriculum Materials
in Science
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Motivation/Learning Goal

• Because molecular biology will continue into the
  twenty-first century as a major frontier of
  science, students should understand the chemical
  basis of life not only for its own sake, but
  because of the need to take informed positions on
  some of the practical and ethical implications of
  humankind's capacity to manipulate living
  organisms. (NRC, 1996, p. )

Observable Phenomenon phenotype
Gene genotype
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Dissertation Work

• Cognitive research
• What are the challenges to reasoning about
  genetics? C.3.2 Exploratory study of
  high school students
• 2. What domain-specific knowledge types are
  important for generative reasoning in genetics?
  C.3.2
  Study of college level introductory biology
  course
• Design research
• 3. How can we design instruction to promote
  generative and systemic reasoning in genetics?
  C.3.1
  The design and enactment of a high
  school genetics unit

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The Levels of Genetic Phenomena
Informational content (genetic code)
These phenomena are composed of two ontologically
distinct types of levels
ATGCCGTACAGCA
Information level
Physical level
Physical entities in the system that represent or
act on information
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Genetic Phenomena
Organs
Tissues constitute organs
Tissues
Cells constitute tissues
Cells
Proteins are the active agents in cells
Proteins
Genes code for proteins
Genes
Genetic information
DNA molecule
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Study 1 Research Questions

• What does reasoning about genetic phenomena
  entail?
• What is challenging for students?
• What conceptual resources do students posses that
  we can build on?

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Findings

• The majority of the students conceived of genes
  as coding for structures and functions at
  multiple organization levels.
• Students were not aware of the centrality of
  proteins in genetic phenomena.
• Students were able to reason about the
  hierarchical structure of the system they were
  able to explain how changes to one level would
  affect a subsequent level.

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Implications

• Because molecular biology will continue into the
  twenty-first century as a major frontier of
  science, students should understand the chemical
  basis of life not only for its own sake, but
  because of the need to take informed positions on
  some of the practical and ethical implications of
  humankind's capacity to manipulate living
  organisms. (NRC, 1996, p. )

DNA/Gene
Current instruction
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Study 2 Research Questions

• What types of domain-specific knowledge are
  important for generative reasoning in genetics?
• What is the nature of the different knowledge
  types?
• What is their role and contribution to reasoning?
• What are typical interactions between these
  different knowledge types?

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Undergraduate Context

• Bio 210-2Molecular Genetics Introductory
  biology for majors
• Five weeks of instruction, lecture based with
  power point slides
• Topics
• Recombinant DNA technology
• Genomes and DNA structure
• Gene expression and its regulation
• RNA processing and translation
• Applications of molecular genetics

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Domain-Specific Knowledge Types

• Domain-Specific Heuristics
• Genes-code-for-proteins
• Proteins-as-central
• Effects-through-interaction
• Domain-Specific Explanatory Schemas
• Inhibit Catalyze
• Translation Build
• Structure-function Activate
• Allosteric-regulation Transport
• Regulation-of-gene-expression Detect

Define key components and dynamics in the system
Define common mechanisms in the system
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Domain-Specific Heuristics
Define key components and dynamics in the system
Genes-code-for-proteins heuristic
Generative, mid-level of specificity,
principle-like
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Cognitive Model
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Designing the High School Genetics Unit

• Study 3 Research Question
• How can we scaffold generative and systemic
  understandings that will promote scientific
  literacy in genetics?

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Theory-Based Design
Cognitive Obstacles (Study 1)
Cognitive Model (Study 2)
Genes code for everything
Genes-code-for-proteins
Instructional Design (Study 3)
Learning Objectives
Genes code exclusively for proteins
Design Solution
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Design Solution Learning Objectives

• Enduring understandings (Wiggins McTighe,
  1998)
• The genetic information solely specifies the
  structure of proteins
• Proteins are central entities in the system they
  carry out a multitude of functions
• Refine students understandings of
  structure-function correlations at the molecular
  level. The amino acid sequence of a protein
  defines its properties

Domain-specific heuristics and schemas
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Design SolutionLearning Objective 1
Lesson1 What is the additional risk factor?
Organs
Lesson2 Clogged arteries excess LDL in blood
Bootstrap the mapping of information by providing
the molecular mechanism first
Tissues
Lesson 3 Excess LDL in blood no up-take of LDL
by cells receptor for LDL
Cells
malfunctioning abnormal structure abnormal
sequence
Proteins
Lesson 4 Abnormal amino acid sequence mutation
in the gene
Gene for FH
Lesson 5 Complete explanation
Lesson 6 Other examples
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Design Solution Learning Objectives 2 3

• Proteins as central mediators of genetic effects
• Motivated exploration of the molecular
  mechanisms involved in genetic phenomena
• An in depth investigation of one disease
• Contrasting of several cases that differ along
  important dimensions of protein function
• The structure of proteins (amino acids) affects
  their function
• Represent protein as a string that folds onto
  itself
• Comparison of structure-function correlations in
  different patients
• Design a protein activity propose a sequence of
  amino acids that will afford specified functions

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Design Solution Learning Objectives 2 3
Focused investigation of protein structure and
function-comparison across patient cases
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Generative Reasoning about Novel Phenomena
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Thank You
The End