Curriculum
Module 02 · 35 min
Reading Pathway Diagrams
Arrows, T-bars, dashed lines — what they mean and where they lie.
CoreClinicalResearch
Topics
What this module covers
- 01KEGG vs Reactome vs WikiPathways conventions
- 02Activation vs inhibition vs translocation
- 03Compartment boxes (nucleus, mitochondrion, membrane)
- 04When a diagram hides kinetics
Learning objectives
By the end of this module you will be able to
- L01Decode standard pathway-diagram glyphs from KEGG and Reactome.
- L02Identify what a diagram does NOT tell you (rate, abundance, context).
- L03Translate a textbook arrow into a hypothesis you could test.
Expected takeaways
What you should walk away believing
- →A pathway diagram is a hypothesis, not a measurement.
- →Compartment matters: the same enzyme can act differently in cytosol vs mitochondrion.
- →Most diagrams omit feedback loops — they're there.
Core summary
At the Core level
Pathway diagrams use a small visual vocabulary: arrows for activation, T-bars for inhibition, dashed lines for indirect or hypothesized links. Boxes group compartments. Read them like a map, not a recipe.
Evidence-graded claims
Claims, scored A–F
F
All pathway diagrams represent measured kinetics
Most are qualitative graphs.
A
Reactome covers >2,500 human pathways
Per Reactome v90 statistics.
Quiz
Check your understanding
Q1. What does a T-bar (⊣) typically denote?
Q2. Dashed arrows usually mean…
Flashcards
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Front
T-bar in pathway diagrams?
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Pathway Atlas