John Hay
John Hay Biomedical
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Genetics of Disease (Medical Interventions)
Unit 2: Unit 2.1 Gene ExpressionMI 2.1Biotechnology Research and Experiments

Compute Fold Change

Use molecular-test evidence to compute fold change accurately.

Builds on (2 levels back)inferred · high confidence
  • Control logic: Molecular results need positive and negative controls.
  • Signal interpretation: Bands, colors, curves, and E-values must be compared to a rule.

Prerequisites are inferred: pending teacher review.

Re-learn the skill with worked practice and clear examples.

Use molecular-test evidence to compute fold change accurately.

Step 1: Learn the key
Read the control , compare the sample signal to the , and report the result with one .
GeneControlTreatedFold
X62424/6 = 4
Y1055/10 = 0.5
Fold-change table
Step 2: Use the model
Read the figure, table, control, range, or protocol before choosing an answer.
Step 3: Name the limit
Say what the evidence can support and what it cannot prove yet.
Practice

Use the molecular figure/table. Which interpretation is best supported?

Reviewed
GeneControlTreatedFold
X62424/6 = 4
Y1055/10 = 0.5
Fold-change table
  1. A.The controls can be ignored once the sample has a signal
  2. B.The sample should be compared to the controls or cutoff before making a call
  3. C.Any color or band on the figure means the same thing
  4. D.The sample result can be read off the figure title without checking the controls
Show the worked solution ▾

Answer: B. The sample should be compared to the controls or cutoff before making a call

  1. Step 1: Use controls/cutoff: The figure/table gives the comparison needed.
  2. Step 2: Make a careful call: A molecular result needs comparison before interpretation.

Why it's right: Controls or cutoffs give the sample signal meaning.

Why the others miss:
  • A: Controls are required.
  • C: Different signals can mean different things.
  • D: Titles do not determine results.

Aligned to Biotechnology Research and Experiments · reading level ~grade 9

Where you'd see this
  • In Unit 2.1 Gene Expression, this skill turns class evidence into a result another person can check.
Careers that use this
Molecular Technologist: Uses compute fold change to make a decision from evidence without overclaiming.
Video library
Watch: Compute Fold Change
RPKM, FPKM and TPM, Clearly Explained!!!
StatQuest with Josh Starmer · ~10 min
Guided notes

Fill these in as you work through the lesson.

Big idea: Use molecular-test evidence to compute fold change accurately.
Key terms: write the meaning
  • Control (known check for a test):  
  • Signal (visible or measured output):  
  • Threshold (cutoff for making a call):  
  • Validity (whether the result can be trusted):  
The rule

Read the control  , compare the sample signal to the  , and report the result with one  .

Check yourself
  1. Did positive and negative controls work? 
  2. What signal did the unknown show? 
  3. Is the result inside the reliable range? 
Work one example

Use the molecular-test figure to practice compute fold change and write one valid result call.