• The Nucleus contains genes organized into two parts
  • Each part is called a genome
    • One is sourced from you mother and one from your father
  • Genomes are not the same
• Breaking up the genome into pieces those are called chromosomes
  • Humans have 23
  • Having two genomes makes us 2N
• Each chromosome has a bunch of genes that are divided up into three parts: the promoter (beginning), coding region (middle), and the terminator (end)
  • Each gene has enough information for a protein
  • Each genome has enough information to generate a human

• The epigenome is defined as the collection of DNA, RNA, proteins, and their chemical modifications (generally altering gene expression)
  • Epigenetic modifications are done by adding marks to the tails of histones
    • The addition of an acetyl group causes the tale to relax and release DNA
      • This increases transcription
    • Methyl groups can either increase or decrease that pattern of gene expression depending
      • putting this directly on DNA permanently shut it down
• When the envoirnment of a cell changes it creates epigenetic modifications
  • This is also very useful to cancers as more than half of known cancers contain mutations involved in regulation

### DNA Packaging

• Packaging DNA starts with the assembly of a nucleosome via eight separate histone protein sub units attaching to the DNA
  • This creates a tight loop called the nucleosome
• Multiple nucleosomes are coiled together and stacked on top of eachother creating what is known as chromatin
  • These are then looped and further packaged
• These make tightly formed structures called chromosomes
• DNA is in usually a less organized form during division