I need help with this lab. Part 1: Monohybrid Crosses – Simulation…
I need help with this lab. Part 1: Monohybrid Crosses – Simulation of Mendel’s Work
When a individual copulate of alleles is involved in one trait, such as green peas, Mendel found that crossing individuals with heterozygous genotypes ( Gg x Gg ) would result in both dominant allele ( chicken pea color ) and recessive ( green pea color ) phenotypes among the young. Crosses such as these, where ONLY one allele match and its result phenotypes are investigated are called monohybrid crosses. Mendel studied seven different traits in pea plants and saw that each time he conducted monohybrid crosses he could expect a phenotypical ratio of 3:1. Three offspring having the dominant phenotype and 1 having the recessionary. Data collected from counting 1000s of offspring produced by monohybrid crosses allowed Mendel to determine the law of segregation, which states that each trait should have at least two inheritable alleles, these alleles should segregate during gamete constitution and at fertilization organisms again have two alleles one from each parent. In this experiment you will be simulating a monohybrid cross using any 2 bilateral ( fair ) coins that you have. Since each coin has 1-heads and 1-tails it will represent a heterozygous parent ( Hh ). You will use two coins at the lapp time, then your intersect is Hh x Hh, a monohybrid cross. Question: When simulating a monohybrid cross does Mendel ‘s conclusion that Hh x Hh results in 3:1 phenotypical and 1:2:1 genotypic proportion hold true ? Hypothesis: Materials:
- (2) Any two-sided fair coin (heads on one side, tails on the other)
- You will pick up 2 coins. Each side represents one allele of the same gene, Heads (H) and tails (h), respectively. Since each coin has 1-heads and 1-tails it will represent a heterozygous parent. Since you will use two coins at the same time your cross is Hh x Hh.
- To simulate a monohybrid cross, you will toss TWO coins, SIMULTANEOUSLY, each coin represents one of the heterozygous parents (Hh x Hh).
- Record the resulting genotype from the tossed coins, which side lands face up for each coin. The only possibilities that can be made from this toss are: HH (homozygous heads), Hh (heterozygous heads), or hh (homozygous tails). Mark the resulting genotype and phenotype in the data table.
- Pick up your two coins and conduct the same process (steps 1-3) 14 more times (15 total trials). Record your data in Table 1.
Results: Table 1: Monohybrid Cross Simulation – 2 bilateral coin flip
|Trial||Offspring Genotype||Offspring Phenotype|
Total number of offspring with:
- Homozygous dominant genotype:
- Heterozygous genotype:
- Homozygous recessive genotype:
- Calculate the genotypic ratio of your data:
Total number of offspring with:
- Dominant Phenotype:
- Recessive Phenotype:
- Calculate the phenotypic ratio of your data:
- What is the dominant trait and how do you know it is dominant?
- What is the recessive trait?
- What are the genotypes of the parents?
- What are the phenotypes of the parents?
- Fill in Punnett Square on the right using the parents given in the procedure
male __________ x Female __________
- Looking at your Punnett square, what is the genotypic ratio?
- Does your genotypic ratio from the coin toss match the ratio of your Punnett square? (You calculated this in the results section) Why or why not?
- Looking at your Punnett square, what is the phenotypic ratio?
- Does your phenotypic ratio from the coin toss match the ratio of your Punnett square? (You calculated this in the results section) Why or why not?
- In Mendel’s paper he provided data for 1000s of monohybrid crosses. How did having this large amount of data allow Mendel to arrive at his final conclusion of a phenotypic ratio of 3:1 and a genotypic ratio of 1:2:1 for monohybrid crosses?
- Was your hypothesis supported by your data? Why or why not?
- Is there anything you could have changed about this experiment so that your hypothesis was better tested?