Frequently Asked Questions

Answers to common questions about Allele & Slide and the genetics behind its calculators.

Is Allele & Slide free?

Yes. Every calculator and guide is free, with no account or download. The site is supported by advertising.

Is my data stored?

No. Everything you enter is processed in your browser and never sent to our servers. See the Privacy Policy.

Can I use the calculators for homework?

Yes, to check your working. Each tool shows the steps, and the guides explain how to do the calculation by hand, which is what exams test.

How many genes can the Punnett square handle?

Up to three, a trihybrid cross with an 8 × 8 square of 64 cells. Larger crosses are easier to solve with the product rule.

Why is my dihybrid ratio not 9:3:3:1?

That ratio needs both parents heterozygous for both genes. Other parents give other ratios, such as 3:3:1:1 or 1:1:1:1.

What does 2pq mean?

The frequency of heterozygotes in Hardy-Weinberg equilibrium, the carriers of a recessive allele.

Can the Hardy-Weinberg tool tell me my risk of having an affected child?

No. It shows population averages. Personal risk depends on family history and testing; please speak to a genetic counsellor.

Can a blood type rule out a father?

Not reliably. Rare variants and errors can make true relationships look impossible. Parentage needs DNA testing.

What p-value means my cross fits the ratio?

By convention, p of 0.05 or more means the data are consistent with the ratio. It is not proof that the ratio is correct.

Why are expected counts under 5 a problem?

The chi-square approximation becomes unreliable. Combine classes or collect more data.

Which Tm should I trust?

For short primers, the Wallace rule; for longer ones, the salt-adjusted formula or a nearest-neighbour tool. Compare primers using the same method.

Does the doubling time calculator work for cancer cells or populations?

It works for anything growing exponentially, but only during the exponential phase. Real populations slow down as resources run out.

Why does the Punnett square assume genes assort independently?

Because that is Mendel's second law, which holds for genes on different chromosomes or far apart on one. Linked genes break it: parental combinations appear more often than the square predicts, and the excess is used to map the genes.

How many degrees of freedom should I use?

The number of classes minus one for a ratio from theory: 1 for 3:1, 2 for 1:2:1 and 3 for 9:3:3:1. A Hardy-Weinberg test with two alleles has 1, because the allele frequency is estimated from the data.

What is the difference between genotype and phenotype ratios?

A genotype ratio counts allele combinations, such as 1 AA : 2 Aa : 1 aa. A phenotype ratio counts visible traits; with complete dominance, AA and Aa look the same, giving 3 : 1.

Do you plan to add linkage maps?

Possibly. Tell us through the contact page if a recombination frequency or map distance tool would help your course.