Epigenetics Flashcards
Define epigenetic traits
phenotype that results from changes in gene expression without alterations in the D N A sequence
Genome is modified in diverse cell types during lifetime of organism to produce many epigenomes
What does methylation do? How does it relate to CPG Islands
methylation occurs on cytosine bases adjacent to guanine, which are clustered in regions called CpG islands.
CpG islands by essential genes are unmethylated and available for transcription.
What does acetylation do?
Opens up chromatin structure to allow for transcription
What are long non coding rnas
similar to mRNAs but don’t code for amino acids, regulates gene expression and chromatin modification by binding to chromatin modifying enzymes
What is Monoallelic expression and What are examples of mono allelic expression
Only one allele is transcribed, while the other allele is transcriptionally silent.
parental imprinting of only one allele, inactivation of x chromosome, random monoallelic expression
Describe epigenetic heritability -
Rats that were fed a reduced protein diet had offspring with a variable expression of yellow phenotype, mice raised with low maternal nurturing don’t adapt well to stress as adults, differences in glucocorticoid receptor levels
What mechanisms do epigenetic changes occur
Methylation, Histone modification and chromatin remodeling, noncoding rna
What catalyzes methylation
methyltransferase groups
What do added methyl groups do?
They occupy the major groove of DNA and silence genes by blocking the binding of transcription factors and other proteins needed to form transcription complexes.
What does heterochromatic methylation do>
maintains chromosome stability by preventing translocations and other chromosomal abnormalities
What is chromatin composed of
DNA wound around an Octamer of histone proteins to form nucleosomes\
What is the histone code
sum of complex patterns and interactions of histone modifications that change chromatin organization and gene expression
What is miRNA and what does it do
Small noncoding RNA that participates in epigenetic regulation of gene regulation and associates with protein complexes to form RNA induced silencing complexes
What are the four classes of lncRNA loci
Antisense, intronic, bidirectional, intergenic
What can lncrna function as
Decoy, adapter, guide, enhancer
What produces allele specific imprinting and subsequent gene silencing
Differential methylation of CpG rich regions
What is true about imprinting?
Its reprogrammed in every generation by changing the methylation pattern
What is true about Prader-Willi syndrome, Angelman syndrome, and Beckwith-Weidemenn syndrome
These Imprinting disorders have their origins during fetal growth and development.
Why are children born after IVF at risk of very low birth weight
External factors that disturb imprinting cause phenotypic consequences.
What is true about epigenetic mechanisms in cancer
They can replace mutations as a way of silencing individual tumor suppressor genes or activating oncogenes
What is true about stress induced behavior.
It can cause epigenetic changes that influence behavior
