Gel electrophoresis lab
Fri, Oct 23, 2026 · Week 9 · Genetics of Disease (Medical Interventions)
Today's goal: Run or model gel electrophoresis and interpret band positions to compare DNA fragments.
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.
I recorded how far each band traveled from the well and used the size ladder to estimate the unknown bands.
Ranking, largest to smallest: Band 1 traveled the least (largest), then Band 2, then Band 3 traveled the farthest (smallest).
Size estimates: Unknown Band 2 lined up between the 1000 bp and 750 bp ladder bands, so I estimate about 850 bp. Unknown Band 3 lined up near the 500 bp ladder band, so I estimate about 500 bp.
Why smaller fragments travel farther: DNA is negatively charged, so the electric field pulls all fragments toward the positive end. The agarose acts as a sieve, and smaller fragments thread through the gel's pores more easily, so they move farther in the same time.
| Band | Migration distance | Size estimate |
|---|---|---|
| Ladder 1000 bp | 18 mm | 1000 bp (known) |
| Unknown Band 2 | 21 mm | ~850 bp |
| Ladder 500 bp | 30 mm | 500 bp (known) |
| Unknown Band 3 | 30 mm | ~500 bp |
This model shows the level of evidence and organization needed to complete: Completes the gel lab analysis: a banding data table with migration distances, a largest-to-smallest ranking, two size estimates against the ladder, and an explanation of the size-migration relationship.
- State the question and method.
- Present the observations and data with units.
- Explain the result, limitations, and next investigation.
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: Submit your data table and interpretation to Schoology.
Turn in: Gel banding interpretation
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 gel electrophoresis lab. 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 fragment size to migration distance on a gel.
- 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.