New Study Breaks the Mendel’s Law of Inheritance

Syllabus: GS3/Science and Technology

Context

• Researchers have found that several inherited traits in the mouse genome break the rules Gregor Mendel laid down in the 19th century about how genes work.

Outcomes of the Study

• Genome-wide association studies, studies that look for the genetic variants linked to diseases — may be missing a significant fraction of heritable variation because that variation is not in the sequence. 
• Allele-specific epigenome-wide association studies, which trace methylation patterns rather than sequence variants, could find parts of the genome associated with diseases that conventional methods miss.
  • DNA methylation is an epigenetic mechanism involving the transfer of a methyl group onto the C5 position of the cytosine to form 5-methylcytosine. 
  • It regulates gene expression by recruiting proteins involved in gene repression or by inhibiting the binding of transcription factor(s) to DNA.
• The study may have implications on human health, and be able to explain conditions that have long resisted genetic analysis.

About Mendel’s Law of Inheritance

• Mendel is known as the father of genetics because of his ground-breaking work on inheritance in pea plants 150 years ago.
• Law of Segregation: Each individual has two alleles for a trait, but only one allele is passed on to the offspring during gamete formation. Traits are determined by pairs of alleles.
  • During meiosis, the two alleles segregate (separate), so each gamete receives only one allele.
• Law of Independent Assortment: Genes for different traits assort independently of one another during gamete formation.
  • The inheritance of one trait (e.g., plant height) does not affect the inheritance of another trait (e.g., seed color), assuming the genes are on different chromosomes. This explains the variety in traits among offspring.
• Law of Dominance: When two different alleles are present in a pair, one (the dominant allele) masks the expression of the other (the recessive allele).
  • In a heterozygous condition (e.g., Tt), the dominant trait (tallness) is expressed, and the recessive trait (shortness) is hidden.
• Significance: Mendel’s principles are the basis for classical genetics, helping us understand how traits are passed from one generation to another.

Source: TH