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ID 16190

Some genes are dominant.

Description:
Cross pure-bred pea plants to identify dominant flower color.
Transcript:
HI! You are using pea flower color as a trait to do plant breeding experiments. You have a pure-bred colored flower plant and a pure-bred white flower plant. What do you do to see which color is dominant? You cross-fertilize the pure-bred colored flower pea plant with the pure-bred white flower pea plant. That is correct. You self-fertilize the pure-bred colored flower plant. No, you have to have both alleles of the flower color gene in one plant to test dominance. You self-fertilize the pure-bred white flower plant. No, you have to have both alleles of the flower color gene in one plant to test dominance. White and colored are two alleles of the flower color gene. When one plant inherits both alleles – white from one parent and colored from another – the dominant allele is expressed. You plant and grow the seeds from the cross-fertilization. What kind of flowers do you expect if colored flower is dominant? All the plants in the F1 generation will have pale colored flowers. No, since colored is dominant, the F1 plants will all be colored. All the plants in the F1 generation will have white flowers. No, since colored is dominant, F1 plants will not have white flowers. All the plants in the F1 generation will have colored flowers. That is correct. There will be plants that have 3 flower colors: white, pale colored and colored flowers. No, all the flowers of one plant will have the same color. In fact, colored is the dominant allele and all the plants in the F1 generation have colored flowers. If we use C for the colored allele and c for the white, what is the genotype of these F1 plants? All the plants are CC. No, this is the genotype of a pure-bred colored flower plant. All the plants are Cc. That is correct All the plants are cc. No, this is the genotype of a pure-bred white flower plant. Some of the plants are CC, some are cc. The numbers are random. No, you've cross-fertilized a pure-bred colored with a pure-bred white. You won't get pure-bred colored and whites in the F1 progeny. In a cross between two plants pure-bred for different flower color alleles (CC and cc), the F1 progeny will be (Cc). Offspring have one copy of each parental allele. When a pure-bred colored flower plant is cross-fertilized with a pure-bred white flower plant, all the F1 plants have colored flowers. Colored is the dominant phenotype. The genotype of the F1 plants is Cc. These F1 plants are: homozygous for the colored flower allele. No, these plants have two different flower color alleles, C and c. homozygous for the white flower gene. No, these plants have two different flower color alleles, C and c. heterozygous for the flower color gene. That is correct. The F1 progeny are all heterozygous for the flower color gene. If you let a plant that is heterozygous for flower color self-fertilize, what will you see in the next generation? All the plants have colored flowers. No, the parent plant is heterozygous; offspring can inherit two white alleles. Most are white flower plants, though some are colored. No, colored is the dominant allele. There will be more CC and Cc plants that are colored than cc plants that are white. Most are colored flower plants, though some are white. That is correct All the plants have white flowers. No, the parent plant is heterozygous; not all offspring will inherit two white alleles. Heterozygous parents can pass on the dominant or the recessive allele. Offspring that inherit both recessive alleles will show the recessive phenotype – in this case white flowers. Offspring that inherit one or two dominant alleles will show the dominant phenotype – in this case colored flowers. Most of the plants will have colored flowers. CONGRATULATIONS! YOU'RE SO SMART!
Keywords:
allele, dominant allele, dominance, cross fertilization, Pure-bred white flowered, pure-bred colored flowered, pea plants, alleles, genotype, gregor mendel, self-fertilize, expressed, F1 generation, progeny, offspring
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Creative Commons License This work by Cold Spring Harbor Laboratory is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.

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