Monohybrid Cross Explained

Nicole Lantz
13 Apr 202002:45

Summary

TLDRThis video explains the concept of a monohybrid cross, where two heterozygous parents are crossed to predict offspring genotypes and phenotypes for a single gene. Using pea plants as an example, it highlights how yellow is dominant and green is recessive. The video walks through a Punnett square to show that the offspring will have a 1:2:1 genotype ratio and a 3:1 phenotype ratio, with about 75% producing yellow peas and 25% producing green peas. This is a fundamental example of Mendelian genetics.

Takeaways

  • 🌱 A monohybrid cross involves two heterozygous parents with respect to a single gene.
  • 🧬 Each parent in a monohybrid cross carries two different alleles for the gene.
  • 🍀 'Mono' refers to one gene, while 'hybrid' refers to the mixing of different alleles.
  • 🌿 Pea plants are a classic example for explaining monohybrid crosses, where pea color (yellow or green) is determined by two alleles.
  • 💛 The yellow pea color is dominant, while the green pea color is recessive.
  • ⚖️ The offspring's genotype ratio in a monohybrid cross is typically 1:2:1 (homozygous dominant : heterozygous : homozygous recessive).
  • 🌻 The phenotype ratio in a monohybrid cross is typically 3:1, with yellow peas being more common than green peas.
  • 🧪 If you complete a monohybrid cross with 100 offspring, approximately 75 will have yellow peas, and 25 will have green peas.
  • 📊 The 3:1 phenotype ratio indicates that both parents are heterozygous.
  • 🔍 The script introduces fundamental principles of Mendelian genetics and suggests exploring further topics like dihybrid and test crosses.

Q & A

  • What is a monohybrid cross?

    -A monohybrid cross is a mating event between two parents that are heterozygous for a single gene, meaning each parent carries two different alleles for that gene.

  • What does 'mono' and 'hybrid' mean in the context of a monohybrid cross?

    -'Mono' refers to the single gene being considered, and 'hybrid' refers to the fact that each parent has two different alleles for that gene.

  • Can you provide an example of a monohybrid cross using pea plants?

    -Yes, a classic example is using pea plants with two possible pea colors: yellow (dominant) and green (recessive). The cross involves heterozygous plants for these traits.

  • What are the possible genotypes for the offspring of a monohybrid cross?

    -The possible genotypes for the offspring are homozygous dominant, heterozygous, and homozygous recessive.

  • How can you predict the genotypes and phenotypes of the offspring in a monohybrid cross?

    -By setting up a Punnett square, you can predict the genotypes and phenotypes of the offspring, showing a 1:2:1 ratio for genotypes and a 3:1 ratio for phenotypes.

  • What is the expected phenotype ratio for the offspring of a monohybrid cross involving pea plants?

    -The expected phenotype ratio is 3:1, with 3/4 of the offspring having the dominant phenotype (yellow peas) and 1/4 having the recessive phenotype (green peas).

  • If you were to create 100 offspring from a monohybrid cross, what would be the expected numbers of each phenotype?

    -You would expect around 75 yellow pea-producing plants and 25 green pea-producing plants.

  • Why might you not get the exact expected numbers in a real monohybrid cross experiment?

    -Variability in the actual breeding process and random chance can lead to deviations from the expected numbers, although the ratios should still hold true over a large number of offspring.

  • What does a 3:1 offspring phenotype ratio suggest about the parents in a monohybrid cross?

    -A 3:1 phenotype ratio suggests that both parents are heterozygous for the gene in question.

  • Can you provide more information on dihybrid crosses and test crosses?

    -Yes, dihybrid crosses involve two genes, and test crosses are used to determine the genotype of an individual when its phenotype is known, which can be explored in further videos.

  • What is the significance of the 1:2:1 genotype ratio in a monohybrid cross?

    -The 1:2:1 genotype ratio is significant because it reflects the expected distribution of genotypes in the offspring when two heterozygous parents are crossed, following Mendel's laws of inheritance.

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関連タグ
GeneticsMendelianCrossbreedingPea PlantsAllelesDominantRecessivePunnett SquareHeterozygousPhenotype
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