Amoeba Sisters is a popular YouTube channel that provides educational content on biology and genetics. One of their popular videos is the “Dihybrid Crosses (Mendelian Inheritance)” video, which explains how dihybrid crosses work and how to solve them. This article will provide a recap of the video and the answer key to the dihybrid crosses problems.
What is Mendelian Inheritance?
Mendelian inheritance is the basic principles of genetics discovered by Gregor Mendel in the 19th century. Mendel studied the inheritance of traits in pea plants and discovered that traits are passed down from parents to offspring in a predictable manner. He also discovered the laws of segregation and independent assortment, which are the basis for understanding dihybrid crosses.
What are Dihybrid Crosses?
Dihybrid crosses are crosses between two individuals that differ in two traits. For example, a cross between a plant with round yellow seeds (RRYY) and a plant with wrinkled green seeds (rryy) would be a dihybrid cross because it involves two traits: seed shape and seed color. A dihybrid cross can be solved using the principles of Mendelian inheritance and the Punnett square.
How to Solve Dihybrid Crosses?
To solve a dihybrid cross, you first need to determine the genotype of the parents. For example, if you have a plant with round yellow seeds (RRYY), you know that it is homozygous dominant for both traits. If you have a plant with wrinkled green seeds (rryy), you know that it is homozygous recessive for both traits.
Next, you need to create a Punnett square to determine the genotype and phenotype of the offspring. The Punnett square is a grid that shows all possible combinations of alleles from the parents. The genotype of the offspring can be determined by filling in the Punnett square with the alleles from each parent.
Answer Key to Dihybrid Crosses Problems
The Amoeba Sisters video on dihybrid crosses provides several examples of problems that involve dihybrid crosses. Here are the answer keys to those problems:
Problem 1:
Parents: RrYy x RrYy
Punnett square:
Offspring: 9/16 round yellow, 3/16 round green, 3/16 wrinkled yellow, 1/16 wrinkled green
Problem 2:
Parents: RrYy x rryy
Punnett square:
Offspring: 1/4 round yellow, 1/4 wrinkled yellow, 1/4 round green, 1/4 wrinkled green
Problem 3:
Parents: RrYy x Rryy
Punnett square:
Offspring: 3/8 round yellow, 3/8 wrinkled yellow, 1/8 round green, 1/8 wrinkled green
Conclusion
Understanding dihybrid crosses and Mendelian inheritance is an important part of genetics. By watching the Amoeba Sisters video on dihybrid crosses and using the answer key provided in this article, you can improve your understanding of this topic and be better prepared for genetics exams and assignments.
