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Punnett Square


A tool that helps to show all possible allelic combinations of gametes in a cross of parents with known genotypes in order to predict the probability of their offspring possessing certain sets of alleles.


It makes use of a grid and letters, i.e. capital letters to represent dominant alleles and lower case letters to recessive alleles. With this tool, the known genotypes of each parent are shown to help predict the possible genotypes of their offspring. It shows how alleles are inherited or passed on to offspring from parents.

It is typically applied in monohybrid crossess and dihybrid crosses in which the theoretical outcomes are based on the assumptions of segregation and independent assortment of alleles (according to Mendelian inheritance).

Deviations from the expected outcomes are observed in the following conditions:

Word origin: named after Reginald Punnett British geneticist, who developed it.

Also called: checkerboard.

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genotype ratio and phenotype ratio in X linked allege

... the genotype and phenotype for a X link recessive gene when after the punnett square the two females are not effect and the two males are effected?

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by greenchicken
Wed Mar 18, 2015 8:57 pm
Forum: Genetics
Topic: genotype ratio and phenotype ratio in X linked allege
Replies: 0
Views: 59

Double heterozygous cross HELP

... Gene A fl/+; Gene B Cre/+ 25% Gene B Cre/+ ??? or I need to do the 16 square Punnett for this dihybrid cross? if so what would be the possibilities? Thank you in advance ...

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by Suzie8
Thu Jan 29, 2015 11:46 pm
Forum: Genetics
Topic: Double heterozygous cross HELP
Replies: 0
Views: 292

Have I understood this punnet square question ?

... on different chromosomes and therefore inherited independently. Using a Punnett square, predict all the possible F1 genotypes. ( please imagine them in a square) SY Sy sY ...

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by girlslovebarbie
Sat Feb 01, 2014 2:55 pm
Forum: Genetics
Topic: Have I understood this punnet square question ?
Replies: 1
Views: 2665

I Need Help understanding gametes, genotypes and phenotypes

... about offspring, it's just about gametes. You don't need to draw a punnett square until the second question. You're doing more work than it is asking you to do. Post ...

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by wildfunguy
Tue Oct 29, 2013 3:25 pm
Forum: Genetics
Topic: I Need Help understanding gametes, genotypes and phenotypes
Replies: 5
Views: 6631

Re: I need help with Punnett Square

The fly been double homozygous the wild type most likely would have had a ratio of around 3:1 for the offspring. No. All of the offspring would have been wild type. The rest of your answer is correct. F0: cross female (Female: BW) x (Male: E) = female bbEE x male BBee F1: All offspring: wild type =...

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by Cat
Sat Oct 05, 2013 1:11 pm
Forum: Genetics
Topic: I need help with Punnett Square
Replies: 1
Views: 4725
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