Mendel's law of independent assortment states that the alleles of two or more different genes get sorted into gametes independently of one another.* I like to think that this means there are no package deals in genetics. There’s no tall, dark, and handsome package and no red hair and freckles package. In other words, the allele a gamete receives for one gene does not influence the allele received for another gene. Independent assortment of genes and their corresponding traits was first observed by Gregor Mendel in 1865 during his studies in genetics of pea plants. Mendel was performing dihybrid crosses, which looked at the inheritance of two traits. He discovered that the combinations of traits in the offspring of his crosses did not always match the combinations of traits in the parental organisms. Let’s look at Mendel’s pea plants for a minute. If you consider the seed pods in the illustration, you notice that both of the seed pods are heterozygous for pod color and form. Constricted pod is dominant to full and green is dominant to yellow. In his monohybrid crosses, when two heterozygotes were crossed, a 3:1 ratio resulted between dominant and recessive phenotypes. However, in dihybrid crosses between two heterozygous individuals, he found a 9:3:3:1 ratio. This shows that each of the two alleles is inherited independently from the other, with a 3:1 phenotypic ratio for each. Notice that both parent pea pods displayed the green, constricted traits. However, that is only one* of the 4 possible gene combinations of the offspring. During meiosis, the pairs of homologous chromosomes split to form haploid cells, and this separation or segregation, of homologous chromosomes is random. This means that all of the maternal chromosomes will not be separated into one cell, while the all paternal chromosomes are separated into another. Instead, after meiosis occurs, each haploid cell contains a mixture of genes from the organism's mother and father. Along with crossing over, independent assortment increases genetic diversity by producing novel genetic combinations.* Let’s consider this. Suppose you cross a purebred, white cat with a short tail with a pure bred, brown cat with a long tail. In the F1 generation, all of the offspring are brown cats with short tails. If coat color and tail length are controlled by two genes that assort independently, what fraction of the F2 kittens are expected to have white fur and short tails? You would find that 3 out of 16 of F2 kittens would have white fur and short tails if the two traits separated independently of one another.*

Question

Mendel's law of independent assortment states that the alleles of two or more different genes get sorted into gametes independently of one another.* I like to think that this means there are no package deals in genetics. There’s no tall, dark, and handsome package and no red hair and freckles package. In other words, the allele a gamete receives for one gene does not influence the allele received for another gene. Independent assortment of genes and their corresponding traits was first observed by Gregor Mendel in 1865 during his studies in genetics of pea plants. Mendel was performing dihybrid crosses, which looked at the inheritance of two traits. He discovered that the combinations of traits in the offspring of his crosses did not always match the combinations of traits in the parental organisms. Let’s look at Mendel’s pea plants for a minute. If you consider the seed pods in the illustration, you notice that both of the seed pods are heterozygous for pod color and form. Constricted pod is dominant to full and green is dominant to yellow. In his monohybrid crosses, when two heterozygotes were crossed, a 3:1 ratio resulted between dominant and recessive phenotypes. However, in dihybrid crosses between two heterozygous individuals, he found a 9:3:3:1 ratio. This shows that each of the two alleles is inherited independently from the other, with a 3:1 phenotypic ratio for each. Notice that both parent pea pods displayed the green, constricted traits. However, that is only one* of the 4 possible gene combinations of the offspring. During meiosis, the pairs of homologous chromosomes split to form haploid cells, and this separation or segregation, of homologous chromosomes is random. This means that all of the maternal chromosomes will not be separated into one cell, while the all paternal chromosomes are separated into another. Instead, after meiosis occurs, each haploid cell contains a mixture of genes from the organism's mother and father. Along with crossing over, independent assortment increases genetic diversity by producing novel genetic combinations.* Let’s consider this. Suppose you cross a purebred, white cat with a short tail with a pure bred, brown cat with a long tail. In the F1 generation, all of the offspring are brown cats with short tails. If coat color and tail length are controlled by two genes that assort independently, what fraction of the F2 kittens are expected to have white fur and short tails? You would find that 3 out of 16 of F2 kittens would have white fur and short tails if the two traits separated independently of one another.*

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Question 1
Genes for traits are found on _____________.
Responses
A the cell membranethe cell membrane
B chromosomeschromosomes
Question 2
Mendel studied heredity in _______ plants.
Responses
A peapea
B beanbean
Question 3
Mendel noticed that various traits in the plants were passed down ________.
Responses
A independentlyindependently
B randomlyrandomly

Answer 1

Question 1: B) chromosomes

Question 2: A) pea
Question 3: A) independently