1. Epigenetic Inheritance
Heritable modifications to gene expression that don’t involve changes to DNA sequence
DNA methylation:
C’s of CpG doublets
Changes in chromatin structure:
- Covalent modifications of histones:
Acetylation or Methylation of Lysines
- Changes in levels of chromatin compaction
Alters ability of TFs to:
Bind to DNA
Activate txn

2. Humans have 23 pairs of chromosomes
2 Sex chromosomes (X & Y)
22 Autosomes
Dosage Compensation: Female & male cells must express X-linked genes at same levels.

3. highly condensed chromatin
X-inactivation in female mammals
At random, Xist gene from one X is transcribed at higher levels & Xist RNA coats X chromosome in cis.
Heterochromatin:
highly condensed chromatin

4. Calico Cats
Females, heterozygous for alleles of an X-linked coat color gene

5. Parental Imprinting
Expression of alleles of some autosomal genes (rare) is determined by which parent they’re inherited from.
Prader-Willi Syndrome (PWS)
PWS gene is methylated during oogenesis
PWS gene is not methylated during spermatogenesis

6. Txn of genes is regulated by binding of TFs to enhancers/silencers.
Chromatin structure can modulate ability of activators to bind to DNA &/or activate txn.