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1
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2
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- A tool to predict the probability of certain traits in offspring that
shows the different ways alleles can combine
- A way to show phenotype & genotype
- A chart that shows all the possible combinations of alleles that can
result when genes are crossed
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3
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- Letters stand for dominant and recessive alleles
- An uppercase letter stands for a dominant allele
- Lowercase letters stand for recessive alleles
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4
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- To set up a Punnett square, draw a large square, and then divide it into
4 equal sections (also squares). It should look something like this:
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5
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- Now you need two parents to mate, ones with a known genotype
- For example, a red flower (genotype Rr) and a white
flower (genotype rr). Rr x rr
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6
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- Place one of the parents on top, and one on the left. You should get a
something similar to this:
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7
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- Finally, take each letter in each column and combine it with each letter
from each row in the corresponding square. You should now have a picture
close to this:
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8
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- The two-letter combinations are the possible genotypes of offspring
- They are: Rr, Rr, rr, and rr genotypes
- From this it is possible to determine the probability (chance) that a
flower will have a red phenotype (2/4 or 50%) or a white phenotype (2/4
or 50%)
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9
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- http://www.borg.com/~lubehawk/psquare.htm
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Notes
