Amoeba Sisters Video Recap: Dihybrid Crosses (Mendelian Inheritance) Vocabulary practicel You probably have had enough of cats with our video. On to peast in pea plants, yellow peas (coded for by a dominant allele Y) are dominant to green peas requiring two recessive alleles yl. Round peas (coded for by a dominant allele R) are dominant to wrinkly peas (requiring two recessive ralleles. These are actual pea plant traits, by the way! For the following, please write in the genotype or phenotype. Some are filled in for you. Genotype Phenotype YYRR Yellow, round 1. Green, Wrinkled YRT 2 VYRR 3. VRE S. Yellow, wrinkled 6. Green, round 7. An allele is a form of a gene. In the cross HhSs x hhss, how many alleles does a kitten inherit from the mother? 8. How many alleles does a kitten inherit from the father? Step 2 HS Hssans hs hsl hs hs Har Gene HhSs Sink Gene hs 9. Gametes, which are se cells, carry the alleles. Why must a gamete carry one allele represented by a letter) from each gene? Meaning, why can’t a gamete carry an “hh” instead of an “hor anh” instead of a “H57”
The Correct Answer and Explanation is :
Correct Answers:
- Green, Wrinkled: Genotype – yyrr
- YyRR: Phenotype – Yellow, Round
- YyRr: Phenotype – Yellow, Round
- yyRr: Phenotype – Green, Round
- Yellow, Wrinkled: Genotype – YYrr
- Green, Round: Genotype – yyRr
Inheritance of Alleles from Parents:
- How many alleles does a kitten inherit from the mother? – A kitten inherits 1 allele per gene from the mother. Since there are 2 genes (H and S), the kitten inherits 2 alleles in total from the mother.
- How many alleles does a kitten inherit from the father? – Similarly, a kitten inherits 2 alleles in total from the father.
Explanation for Gamete Alleles:
- Why must a gamete carry one allele from each gene?
A gamete must carry one allele from each gene because of the process of meiosis, which ensures genetic diversity and proper inheritance. During meiosis, homologous chromosomes (pairs of chromosomes containing the same genes) separate so that each gamete receives only one chromosome from each pair. This is called the Law of Segregation, which Gregor Mendel discovered.
If gametes carried both alleles (e.g., “HH” or “hh”), this would violate the natural balance of inheritance. When fertilization occurs, the offspring would end up with more than two alleles per gene, which is not viable in sexually reproducing organisms like pea plants. Additionally, the Law of Independent Assortment states that alleles for different traits (e.g., “H” for height and “S” for seed shape) segregate independently during gamete formation. This ensures a random combination of traits in the offspring.
Carrying one allele per gene allows gametes to combine during fertilization, restoring the diploid number of chromosomes in the offspring while preserving genetic variation. This system is essential for Mendelian inheritance and maintaining stable genetic patterns across generations.