Exploring mendelian genetics
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Exploring Mendelian Genetics. Independent Assortment To determine if the segregation of one pair of alleles affects the segregation of another pair of alleles, Mendel performed a two-factor, dihybrid cross.

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Exploring mendelian genetics

Exploring Mendelian Genetics


  • Independent Assortment

    • To determine if the segregation of one pair of alleles affects the segregation of another pair of alleles, Mendel performed a two-factor, dihybrid cross.



  • The alleles for round ( yellow peas (genotype RRYY) with true-breeding plants that produced wrinkled green peas (genotype R) and yellow (Y) are dominant over the alleles for wrinkled (r) and green (y).


  • Mendel crossed the heterozygous F1 plants ( yellow peas (genotype RRYY) with true-breeding plants that produced wrinkled green peas (genotype RrYy) with each other to determine if the alleles would segregate from each other in the F2 generation.

    RrYy × RrYy

The Punnett square predicts a 9 : 3 : 3 :1 ratio in the F2 generation.



  • The principle of for seed color. This principle is known as independent assortment states that genes for different traits can segregate independently during the formation of gametes.

  • Independent assortment helps account for the many genetic variations observed in plants, animals, and other organisms.


A summary of mendel s principles
A Summary of Mendel's Principles for seed color. This principle is known as

  • Genes are passed from parents to their offspring.

  • If two or more forms (alleles) of the gene for a single trait exist, some forms of the gene may be dominant and others may be recessive.

  • In most sexually reproducing organisms, each adult has two copies of each gene. These genes are segregated from each other when gametes are formed.

  • The alleles for different genes usually segregate independently of one another.


Beyond mendel
Beyond Mendel for seed color. This principle is known as

  • Some alleles are neither dominant nor recessive, and many traits are controlled by multiple alleles or multiple genes.


Beyond mendel1
Beyond Mendel for seed color. This principle is known as

  • Incomplete Dominance 

    • When one allele is not completely dominant over another it is called incomplete dominance.

    • In incomplete dominance, the heterozygous phenotype is between the two homozygous phenotypes.


Beyond mendel2
Beyond Mendel for seed color. This principle is known as

  • Codominance

    • both alleles contribute to the phenotype.

    • In certain varieties of chicken, the allele for black feathers is codominant with the allele for white feathers.

    • Heterozygous chickens are speckled with both black and white feathers. The black and white colors do not blend to form a new color, but appear separately.


Beyond mendel3
Beyond Mendel for seed color. This principle is known as

  • Multiple Alleles 

    • Genes that are controlled by more than two alleles

    • An individual can’t have more than two alleles. However, more than two possible alleles can exist in a population.

    • A rabbit's coat color is determined by a single gene that has at least

      four different alleles.


Beyond mendel4
Beyond Mendel for seed color. This principle is known as

  • Polygenic Traits  

    • Traits controlled by two or more genes are said to be polygenic traits.

    • Skin color in humans is a

      polygenic trait controlled

      by more than four

      different genes.


Knowledge check
Knowledge Check for seed color. This principle is known as

What is independent assortment?

What are polygenic traits?

What is codominance?

What is incomplete dominance?


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