Law of Segregation

Definition

The Law of Segregation, also known as Mendel's First Law, is a fundamental principle in genetics that describes how genetic traits are passed from parents to offspring. It states that each inherited trait is determined by genes that come in pairs, and that these gene pairs segregate, or separate, during the formation of reproductive cells.

5 Must Know Facts For Your Next Test

1. The Law of Segregation explains how an organism inherits one allele from each parent, resulting in a pair of alleles for each trait.
2. During gamete formation (meiosis), the two alleles for each trait separate, and each gamete (sperm or egg) receives one of the two alleles.
3. When the gametes fuse during fertilization, the offspring inherits one allele from each parent, resulting in a new combination of alleles.
4. The Law of Segregation applies to all diploid organisms, where each cell contains two copies of each chromosome and, therefore, two copies of each gene.
5. This law is a fundamental concept in understanding patterns of inheritance and the expression of genetic traits in offspring.

Review Questions

• Explain how the Law of Segregation relates to the formation of gametes and the inheritance of traits in offspring.
  • The Law of Segregation states that each organism inherits one allele for a particular trait from each parent, resulting in a pair of alleles. During gamete formation (meiosis), the two alleles for each trait separate, and each gamete (sperm or egg) receives one of the two alleles. When the gametes fuse during fertilization, the offspring inherits one allele from each parent, resulting in a new combination of alleles. This process ensures that the offspring receives a complete set of genetic information from both parents and explains the patterns of inheritance observed in offspring.
• Describe the relationship between the Law of Segregation and the concepts of dominant and recessive traits.
  • The Law of Segregation is closely related to the concepts of dominant and recessive traits. Since each organism inherits a pair of alleles for a particular trait, one allele may be dominant and the other recessive. The dominant allele will be expressed in the phenotype, even if only one copy is present. The recessive allele will only be expressed if two copies are present. This explains why certain traits may skip generations or appear to 'disappear' in some offspring, as the recessive allele is present but not expressed. The Law of Segregation, combined with the understanding of dominant and recessive traits, allows for the prediction of the genotypes and phenotypes of offspring using tools like the Punnett square.
• Analyze how the Law of Segregation contributes to the foundation of evolutionary theory and the understanding of genetic variation within a population.
  • The Law of Segregation is a fundamental principle that underpins our understanding of evolution and genetic variation. By explaining how genetic information is passed from parents to offspring, the Law of Segregation demonstrates the mechanism by which genetic diversity is maintained and can be acted upon by natural selection. The random segregation of alleles during gamete formation and their subsequent recombination during fertilization creates a vast array of possible genotypes and phenotypes within a population. This genetic variation is the raw material for evolution, as natural selection can act on the differences between individuals, favoring those with advantageous traits. The Law of Segregation, therefore, is a crucial component of the foundation of evolutionary theory, as it elucidates the processes that generate the genetic diversity necessary for evolution to occur.

Related terms

Alleles:

Different versions of the same gene that determine a specific trait.

Dominant and Recessive Traits: Dominant traits are expressed when at least one copy of the dominant allele is present, while recessive traits are only expressed when two copies of the recessive allele are present.

Punnett Square: A graphical tool used to predict the possible genotypes and phenotypes of offspring based on the genetic information of the parents.