Non-Mendelian Inheritance Patterns

Lecture 8 for Exam 2

What is Mendelian Inheritance?

• Action of genes in organisms that have those genes (genes determine traits)

  • Parental genes determine offspring traits

• Genes pass unaltered

• Law of Segregation (each gamete gets one allele/trait from each parent, reunites during fertilization)

• Law of Independent Assortment (genes aren’t linked which allows for predictable fixed ratios via Punnett Square)

Maternal Effect (contrasts)

• Phenotype depends on genes of mother

  • Contrasts direct influence of traits via gene expression from both parents

Epigenetic Inheritance (contrasts)

• Transient (temporary) chemical modification to DNA

  • Contrasts unaltered gene passing down

    • Ex: env. factors (stress/diet/toxins) will directly affect F1 gen, but not further.

Cytoplasmic Inheritance

• Chromosomes don’t line up neatly on metaphase plate

  • Mitochondria

• Violates LoS

Linkage

• Non-equal probability of inheritance

• Violates LoIA

  • Alleles here can travel together