Monohybrid Cross Lab

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Our class examined many things throughout the Monohybrid/Dihybrid Cross Lab. We examined genetic typical ratios throughout the monohybrid lab and phenotypic ratios throughout the dihybrid lab. We were able to see how traits were being passed on through probability and inheritance through the crossing of alleles.

For the monohybrid cross part we used blue and green colored chips in 2 paper bags. Each bag contained 15 of each color of chip. The bags were labeled male and female, which were the ‘parents’ in the experiment. With my partner we each took one bag and then together drew one chip out of each of our bags at once and looked to see the combination of the two chips. Blue chips represented the dominant allele (B) for blue fur and
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For this lab we used the same 2 bags containing that blue and green chips from before as well as 2 additional bags, each containing 15 yellow chips and 15 red chips. The red chips represented the dominant allele (R) for long fur and the yellow chips represented the recessive allele (r) for short fur. These bags were also labelled male and female. We also created a punnett square for this cross as seen in Figure 3 to see what the possible phenotype combinations for the offspring between the two would be. We concluded that the possible phenotypes were Long Blue Fur, Long White Fur, Short Blue Fur and Short White Fur, with the proportions of the outcomes being 9:3:3:1. With the 4 bags we performed 32 trials of drawing one from each, without looking, and recording the phenotype into a table as seen in Figure 4, and placed the chip back into its corresponding bag. It was important that we returned the chips back to it’s bag and didn’t leave it out because it would have increased the probability to obtain certain results in the lab, not making it an accurate trial. We kept the red and yellow chips separate from the green and blue chips to reinforce Mendel’s idea of the Law of Segregation, the idea that traits/alleles from parents to offspring do not mix or blend, but are separate and discrete from each other. Each offspring/organism receives and or inherits two copies of each gene, one from each parent, that are separate from each other, not blended together. The predicted phenotype ratios were very close in comparison to the actual phenotype ratios in the cross, as the outcome was only off by a select few numbers. In addition to that, the predicted phenotype ratios were also close in number to the actual class totals in the cross, having it be a fairly reliable and good trial to

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