Which part of the living system did you change?
Labs / Biology
Meiosis & Crossing Over
A pair of homologous chromosomes has replicated and lined up. Green segments came from one parent, orange from the other. Grab a crossover knob between the two inner chromatids and slide it — then watch the cell divide twice into four gametes, each with its own mix of alleles.
Labs / Biology / Meiosis & Crossing Over
Meiosis & Crossing Over
A pair of homologous chromosomes has replicated and lined up. Green segments came from one parent, orange from the other. Grab a crossover knob between the two inner chromatids and slide it — then watch the cell divide twice into four gametes, each with its own mix of alleles.
Why it matters
Why explore this?
Living systems are connected and constantly changing. This model makes one biological process visible so you can test how its parts affect one another.
Explore
Try the model
types 2/4crossovers 1recomb 2/4
Investigate
Questions to test
Predict first, try it in the model, then use what you observe to answer.
What to try
- With no crossover, how many genetically different gametes can one cell make?
- Add a single crossover and drag it. Which alleles end up swapped, and which two gametes become recombinant?
- Set a double crossover and slide the two knobs close together. Why can a second crossover undo the first?
- Flip "Alt. assortment" without touching the crossovers. How can gametes change when no segments were swapped?
- What combination of crossovers and assortment produces four completely different gametes?
Explain
Make sense of what happened
Explain the process as a chain: a change happens, the system responds, and that response affects what happens next. Use an observation from the model as evidence.
Check
Before you leave
How did the system respond?
How would you explain that response?
If you can answer all three using evidence from the model, you understand the main idea. If not, return to Explore and change one setting at a time.