Meiosis and Genetic Recombination

Crossing Over in Meiosis

• Definition: Crossing over during meiosis allows recombination of genes between homologous chromosomes.
• Impact on Linkage: Alters the linkage between genes on the same chromosome.
• Frequency: Occurs frequently during prophase I of meiosis.

Tetrad Formation

• Association: Occurs when homologous chromosomes associate with each other.
• Structure: Forms a tetrad.

Inheritance Without Crossing Over

• Parental Chromosome Alleles:
  • One chromosome has alleles A and B.
  • The other chromosome has alleles a and b.
• Haploid Cell Outcome: Each haploid cell will inherit a chromosome with the same allele combination as one of the parental chromosomes.
• Linked Genes: Arrangement remains unaltered without crossing over.

Inheritance With Crossing Over

• Crossing Over Process:
  • Occurs between two individual chromatids.
  • Results in four different genetic combinations in haploid cells after meiosis.
  • Two chromatids remain unchanged with parental combinations:
    • A and B
    • a and b
  • Two chromatids are recombinant:
    • A and b
    • a and B
• Significance: Crossing over allows for the reassortment of linked genes, introducing genetic diversity.