lec 26

Reading Assignments

  • Chapters 9 & 12

Suggested Practice Problems

  • Chapter 9: 3, 4, 5, 7, 8, 10, 16

  • Chapter 12: 4, 9

Terminology

  • Maternal effect

  • Chromatin (condensed vs. open)

  • Nucleosome

  • Histone

Learning Objectives

  • LO51: Understand organelles' phenotypes and their lineage from nuclear and organelle DNA. Explain complex inheritance in mitochondrial diseases.

  • LO52: Explore ways maternal effects shape offspring phenotypes.

  • LO53: Compare DNA compaction in bacteria vs. eukaryotes.

  • LO54: Understand dynamic chromatin states and how they influence gene expression.

Mitochondrial Function

  • Mitochondria import proteins from both nuclear genome and mtDNA.

  • Mutations in nuclear or mtDNA components can cause diseases.

  • mtDNA mutations are inherited maternally.

Myoclonic Epilepsy & MERRF

  • Symptoms consistent with myoclonic epilepsy and ragged-red fiber disease (MERRF).

  • Pedigree construction to reflect mitochondrial inheritance patterns.

  • Understanding of probabilities associated with MERRF inheritance.

Complex Mitochondrial Inheritance

  • Mitochondrial defects lead to various disorders including neuropathies and cancers.

  • Heteroplasmy: presence of multiple mtDNAs in individuals.

  • Variable penetrance and effects of tissue sensitivity.

Mitochondrial Replacement Therapy

  • Three-parent babies technique to prevent mtDNA mutations (approved only for certain circumstances).

Maternal Effect Genes

  • Offspring phenotype affected by the mother’s genotype.

  • Example: D allele in Drosophila affecting embryonic coiling.

Infectious Heredity

  • Inheritance through symbiotic or parasitic microorganisms in host cell cytoplasm.

Chromatin Structure

  • Eukaryotic cells utilize chromatin to compact DNA.

  • Nucleosomes are fundamental units consisting of histones and wrapped DNA.

  • Chromatin state varies across cell types and developmental stages, influencing gene expression.

Chromatin Modifications

  • Reversible covalent modifications (e.g., methylation, acetylation) to histone tails affecting chromatin state and domain structure.