"Make the Right Call!" Lab

Guiding Question: How can you predict the results of genetic crosses?

Hypothesis:
I believe that the best way of prediction genetic crosses, and the inheritance of specific traits is through Punnett Squares. Punnett Squares combine the two different, either dominant or recessive alleles, of both of the parents, to see what the different genotypes of their offspring could be. However, I also do think that Punnett Squares are not always 100% accurate, hence the word "probability in genetics". Sometimes, the offspring may have a completely different genotype for a certain trait then you expected him/her to.

Data Collected:

Data Table 1:

Trial	Allele from Bag 1 (female)	Allele from Bag 2 (male)	Offspring’s alleles
1	B	b	Bb
2	B	b	Bb
3	B	b	Bb
4	B	b	Bb
5	B	b	Bb
6	B	b	Bb
7	B	b	Bb
8	B	b	Bb
9	B	b	Bb
10	B	b	Bb

Data Table 2:

Trial	Allele from Bag 1 (female)	Allele from Bag 2 (male)	Offspring’s alleles
1	B	B	BB
2	B	B	BB
3	B	B	BB
4	B	B	BB
5	B	b	Bb
6	B	B	BB
7	B	b	Bb
8	B	B	BB
9	B	B	BB
10	B	B	BB

Data Table 3:

Trial	Allele from Bag 1 (female)	Allele from Bag 2 (male)	Offspring’s alleles
1	B	b	Bb
2	b	b	bb
3	B	b	Bb
4	B	B	BB
5	B	B	BB
6	B	B	BB
7	b	B	Bb
8	b	b	bb
9	B	B	BB
10	B	b	Bb

Questions/Data Analysis:

1) Make a punnett square for each of the crosses you modeled in Part 1, Part 2 and Part 3.

                         

              

2) According to your results in Part 1, how many diffrent kinds of offspring are possible when the homozygous parents(BB and bb) are crossed? Do the results you obtained using the marble model agree with the results shown by a Punnett square?

According to the results, as well as the Punnett Square, if the parents are homozygous, meaning that both of their alleles are either dominant or recessive, their offpsring will show the dominant trait. However, since one of their parents carry a genotype for the recessive trait (bb), the children will be carriers of the recessive trait. Their genotype would be heterozygous, or Bb. The results that we obtained do show that all of the offspring would have the allele combination of Bb. In this case, the Punnett Square was 100% correct.

3) According to your results in Part 2, what percentage of offspring are likely to be homozygous when a homozygous parent (BB) and a heterozygous parent (Bb) are crossed? What percentage of offspring are likely to be heterozygous? Does the model agree with the results shown by a Punnett square?

When looking at the results that we gathered for Part 2 (the crossing of a heterozygous and homozygous parents), I can gather that they are not quite similar to the results that the Punnett Squares have shown. The Punnett Squares show that the probability of the offspring being heterozygous is 50%. However, in our results, only 20% of the overall picks ended up with both blue and white marbles.The other 50% on the Punnett Square were supposed to be homozygous, or BB. However, in our results showed that the majority of the outcome had the BB combination of alleles (80%). This shows that the more complex the genotype of the parents is, the less reliable the Punnett Square will be.

4) According to your results in Part 3, what diffrent kinds of offspring are possible when two heterozygous parents (BbxBb) are crossed? What percentage of each type of offspring are likely to be produced? Does the model agree with the results of a Punnett square?

When two heterozygous parents are crossed, there are three possible outcomes that could happen. According to the Punnett Squares, if two heterozygous parents are crossed, the outcome would be as follows: 25% of the offspring would have the genotype of BB, 25% would be bb, and finally, 50% of the offspring would inherit exactly the same alleles for a trait as their parents, which is Bb. However, again, the results that I got from the model are quite different from the ones shown in the Punnett Square. It turned out that 40% of the outcomes were Bb, 20% were bb, and the final 40% were BB.

5) For Part 3, if you did 100 trails instead of 10 trails, would your results be closer to the results shown in a punnett square? Explain.

I don't know whether the results would be closer to the ones shown by the Punnett Squares, but I do believe that the data gathered from 100 picks would be more reliable then the one where only 10 picks were made. If 100 picks were made, the data would probably be more accurate, and more statistics would be proved.

6) In a paragraph, explain how the marble model compares with a Punnett square. How are the two methods alike? How are they different?

The two methods are quite similar in a sense that both of them can be used to predict the probability of the offspring inherting certain traits from their parents. However, they do have a major difference. While the Punnett Square is mostly used for predicting what the possible outcome for the genotypes could be, the marble model is a sort of a test for the Punnett Square, showing how reliable the results from the Punnet Square can really be, when applying them to real-life situations.