Disk diffusion and MIC lab
Wed, Sep 30, 2026 · Week 6 · Genetics of Disease (Medical Interventions)
Today's goal: Run a disk-diffusion test and connect zone of inhibition to minimum inhibitory concentration.
This is a model of the work you should turn in today. Use it to check your own: match the structure and the level of detail, do not copy it. Your data and wording should be your own.
Connection to MIC: a larger zone of inhibition means the antibiotic stopped bacterial growth even where it had spread thin and dilute, which points to a lower minimum inhibitory concentration (less drug needed to work).
Comparison, with its limit: C produced the widest zone (22 mm), then A (18 mm), then B (9 mm). Zone width cannot rank different antibiotics against each other, because each drug diffuses through agar at its own rate and each has its own clinical breakpoint, so this ranks the zones, not the drugs.
| Antibiotic | Zone of inhibition (mm) | Effectiveness rank |
|---|---|---|
| Antibiotic C | 22 | 1 (most effective) |
| Antibiotic A | 18 | 2 |
| Antibiotic B | 9 | 3 (least effective) |
This model shows the level of evidence and organization needed to complete: A data table listing each antibiotic, its measured zone of inhibition in millimeters, and an effectiveness ranking, with a sentence connecting zone size to minimum inhibitory concentration.
- Name the variables and include units.
- Enter observations without changing the raw values.
- Check labels, calculations, and patterns before interpreting the data.
Keep the structure. Replace the question, facts, measurements, and evidence. Then recheck units, vocabulary, and whether the conclusion goes beyond the evidence.
Also due today: Bring data table to Thursday's resistance analysis; photograph plate for portfolio.
Turn in: Disk-diffusion data table
Go to Schoology to turn this in.
Submit one PDF. Put your first and last name in the document header. Name the file: FirstName LastName - Assignment Title - YYYY-MM-DD.pdf.
Open Schoology PDF upload helpIf you cannot get in, see Mr. Mendoza. Do not skip the work.
Claim ceiling: Today's evidence supports a classroom claim about today's lesson. It cannot prove causation, diagnose a real patient, or justify action outside this room.
One exam-style question that uses exactly what you practiced today. Try it before you reveal the answer, then read why each choice is right or wrong.
Tap an answer to see the full explanation. Nothing is recorded or graded.
It builds this reusable test skill: Relating zone of inhibition to antibiotic effectiveness and MIC.
- Name the concept or data pattern being tested.
- Cross out choices that violate that rule or the evidence.
- Justify the best remaining choice before checking the answer.