Epigenetics Exam I Flashcards
Epigenetics was first defined by whom?
Conrad Waddington in 1942 as a branch of biology which studies the casual interactions between genes and their products which bring the phenotype into being
Gene Regulation describes what?
How genes are controlled
How do they know what tissue they are in
How do they know what type of cell they are
How do you maintain cell identity and function
Current definition of Epigenetics
Study of changes in gene function that are mitotically and or meiotically heritable and that do not entail a change in the DNA sequence
The change in gene function without change in DNA sequence
Changes in phwnotype not caused by changes in DNA
Heredity
transmission of traits from parents to offspring
Heritability
genetic variance / phenotype variance
How does epigenetics work?
control gene expression acheived through semi reversible covalent modification of DNA bases and the proteins that package DNA and the proteins in the surrounding area of the of the nucleus
Major theoretical challenge
inheritance of acquired characters
Gene Regulatory Network
hard wired
genetic relationships between DNA sequences and their products
Attractors
in dynamic system, a set of physical properties toward which a system tends to evolve regardless of starting conditions of the system.
Chromatin Structure
DNA interaction with histones and non histone proteins produces suffiecient level of compaction to fit into a cell nucleus
Chromatin
generic term for any complex of DNA and protein found in a nucleus of a cell
Chromosomes
separate pieces of chromatin that behave as a unit during cell division. Versatile, modular strucutre for packaging DNA that supports flexibilty of form and funciton
Nucleosome
Basic unit of chromatin DNA, histones, non histone protein Package , hold DNA Where a particular locus is in 3D inside the nucleus Formed from a histone octamer and DNA
Histones
Proteins
H1,H2,H2B,H3,H4
Like stacked blocks
H1 holds end of DNA after it has wrapped around octamer
Major types of Chromatin Structure
Heterochromatin
Euchromatin
Heterochromatin
highly condensed, usually inactive transcriptionally
Types of heterochromatin
constituitive and falcutative
Constitutive
condensed in all cells
Facultative
Condensed in only some cells and relaxed in other cells
Euchromatin
relaxed, usually active transcriptionally