Unit 2: Genome & DNA Organization Flashcards
What is a nucleosome?
A nucleosome is an octamer of histones around which DNA wraps
What are the role of histone tails?
- Are target of histone modifications
- Mediate inter-nuclesosome connections & changes DNA accessibility
What happens when DNA becomes more condensed?
Higher order chromosome structure: the more DNA is condensed, the less accessible it is which represses gene expression
How is the chromosome structure regulated?
Euchromatin: “open” state, more expression
Heterchromatin: “closed” state, less accessible
How does the number of nucleosomes change DNA?
The more nucleosomes, the less accessible DNA which represses expression
What do chromatin remodeling complexes do?
Eject, Add, or Reposition nucleosomes
What does the H3.3 histone variant do?
Locks chromosome structure into open state
What does CENPA do?
Kinetochore attachment sites
What does H2AX do?
Attracts DNA repair proteins
How can histone tails be modified?
By specialized histone modifying enzymes that can ADD or REMOVE modifications such as methylation or acetylation
What are bromodomain proteins?
Stabilize open state
What are Chromodomain proteins?
Stabilize closed state
