Mendel's Law of Inheritance

Mendel's Law of Inheritance

Segregation

• Definition: The law of segregation states that during the formation of gametes, the alleles for a gene separate from each other.
• Key Points:
  • Each parent contributes one allele for each trait.
  • This results in offspring that inherit one allele from each parent.
  • Demonstrated through monohybrid crosses (e.g., TT x tt producing Tt and tt individuals).

Independent Assortment

• Definition: The law of independent assortment states that alleles of different genes assort independently of one another during gamete formation.
• Key Points:
  • Applies to genes located on different chromosomes or far apart on the same chromosome.
  • Demonstrated through dihybrid crosses (e.g., AaBb parents producing AB, Ab, aB, ab offspring).
  • Results in a variety of genetic combinations in offspring.

Dominance

• Definition: The principle of dominance indicates that some alleles are dominant over others and can mask the presence of recessive alleles.
• Key Points:
  • Dominant allele: Expressed in the phenotype even if only one copy is present (e.g., T in Tt).
  • Recessive allele: Only expressed in the phenotype when two copies are present (e.g., t in tt).
  • Complete dominance (dominant completely masks recessive) vs. incomplete dominance (both alleles influence the phenotype) and codominance (both alleles expressed, e.g., AB blood type).

Mendel's Law of Segregation

• Alleles for a gene separate during gamete formation
• Each parent contributes one allele
• Demonstrated with monohybrid crosses: TT x tt producing Tt and tt individuals

Mendel's Law of Independent Assortment

• Alleles of different genes sort independently during gamete formation
• Applies to genes on different chromosomes or far apart on the same chromosome
• Demonstrated with dihybrid crosses: AaBb parents producing AB, Ab, aB, ab offspring

Principle of Dominance

• Some alleles are dominant, masking recessive alleles
• Dominant allele: expressed even with one copy (e.g., T allele in Tt)
• Recessive allele: only expressed with two copies (e.g., t allele in tt)
• There are different types of dominance:
  • Complete dominance: dominant completely masks recessive
  • Incomplete dominance: both alleles influence the phenotype
  • Codominance: both alleles are expressed (e.g., AB blood type)

Explore Mendel's key principles of inheritance, including the laws of segregation, independent assortment, and dominance. Understand how these concepts contribute to genetic variation in offspring through specific examples like monohybrid and dihybrid crosses.