independent assortment- genes that segregate (separately) independently do not influence each...
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Independent Assortment- Genes that segregate (separately) independently do not influence each other's inheritance.
The principle of independent assortment states that genes for different traits can segregate independently during the formation of gametes.
Mendel did a two-factor (trait) cross to see if the separation of one pair of alleles affects the separation of another pair of alleles.Instead of crossing a yellow seed with a green
seed; he observed seed color and seed shape together
Seeds that are round (R) and yellow (Y) are dominant to seeds that are wrinkled (r) & green (y)
True-breeding round & yellow (RRYY)seeds were crossed with true breeding wrinkled and green seeds (rryy)
The result: All individuals in the F1 generation were round & yellow
The Two Factor Cross: F2
Heterozygous F1 plants (RrYy) were crossed 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
9 round & yellow: 3 round & green: 3 wrinkled & yellow: 1 wrinkled & green
The results of the experiment:some seeds were round and yellowsome seeds were wrinkled and greensome seeds were round and greensome seeds were wrinkled and yellow
Mendel had discovered the principle of independent assortment
Independent Assortment explains the variation observed in plants, animals, and other organisms
A Summary of Mendel's Principles
Genes are passed from parents to their offspring.
If there are two or more alleles for a gene, some of the alleles 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
Not all traits or dominant or recessive
Some traits are controlled by more than one gene or many alleles
Incomplete Dominance-
One allele is not completely dominant over the other
The heterozygous phenotype is b/w the two homozygous phenotypes
A cross between red (RR) and white (WW) four o’clock plants produces pink-colored flowers (RW).
Codominance-
both alleles contribute to the phenotype.
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.
Multiple Alleles-
Genes that are controlled by more than two alleles
more than two possible alleles can exist in a population
Coat color in rabbits is determined by a single
gene that has at least four different alleles.
C = full color; dominant to all other alleles
Polygenic Traits-
Traits controlled by two or more genes
Skin, hair, & eye color in humans are polygenic traits controlled by more than four different genes
Thomas Hunt Morgan used fruit flies to advance the study of genetics
Morgan and scientist tested Mendel’s principles and learned that they applied to other organisms as well as plants.
Mendel’s principles can be used to study inheritance of human traits and to calculate the probability of certain traits appearing in the next generation
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