Chapter 16 - Gene Regulation in Eukaryotes II: Epigenetics Flashcards
The study of mechanisms that lead to change in gene expression that are passed from cell to cell and are reversible but don not involve a change in the DNA sequence
Epigenetics
Examples of epigenetics
X-chromosome inactivation and genomic imprinting
Types of molecular changes that underlie epigenetic regulation
DNA methylation, chromatin remodeling, histone modification, localization of histone variants, feedback loops
Epigenetic changes that are maintained at a specific site
Cis changes
Epigenetic changes that are maintained by diffusible factors
Trans changes
How can Cis and Trans changes be observed?
Cell fusion experiments
What are the two categories of epigenetic gene regulation?
Programmed developmental change and environmental agents of change
Regions of chromatin that are not stained during interphase, transcriptionally active, and occupy a central position in the nucleus
Euchromatin
Regions of chromatin that are stained throughout the cell cycle, have a high level of compaction, inhibit gene expression, and are localized along the periphery of the nucleus
Heterochromatin
Roles of heterochromatin
Gene silencing, prevention of transposable element movement, and prevention of viral proliferation
Heterochromatin that is heterochromatic at the same location in all cell types
Constitutive heterochromatin
Heterochromatin that is heterochromatic at varying locations among different cell types
Facultative heterochromatin
The addition of PTMs
Writer domains
The removal of PTMs
Eraser domains
Phases of formation of facultative and constitutive chromatin
Nucleation, spreading, and barrier
How can abnormalities in heterochromatin formation affect humans?
Diseases like ICF and Roberts syndrome
Much of development is regulated by epigenetic regulation, true or false
True
A form of gene regulation in which an offspring expresses the copy of a gene from one parent but not both
Genomic imprinting
Trithorax group (TrG)
involved with gene activation
Polycomb group (PcG)
involved with gene repression
PRC1 may inhibit transcription in three different ways
Chromatin compaction, covalent modification of histones, direct interaction with a transcription factor
Allele with the capacity to induce changes in others at a single locus
Paramutagenic
Allele that has been altered by another allele at the same locus
Paramutable
Effects of paramutation variation
The likelihood that the paramutagenic allele will alter the paramutable allele, and the stability of the paramutagenic allele over generations
Epigenetic changes that are transmitted from parent to offspring are called…
Paramutations
Can the environment cause epigenetic changes?
Yes
Honeybee example
Bees that eat royal jelly into adulthood become queens later in life
