GN 1.5.3 Flashcards
What is genomic imprinting?
An epigenetic modification that results in unequal expression of the maternal or paternal alleles of a gene
What is the role of methylation in cancers?
Some promoters of tumor suppressors can become hypermethylated leading to no transcription of the tumor suppressor gene. On the other hand oncogenes can lose methylation and become activated.
What is Beckwith-Wiedmann Syndrome?
Excess paternal or loss of maternal contributions of genes. IGF2 from the father promoting embryonic growth.
What is the epigenetic model of cancer?
What is the role histone modifications in epigenetics?
This leads to acetylation and deacetylation which affects the levels of transcription of certain genes.
What is the role of miRNA in cancers?
They can inhibit tumor causing genes and degradation of the miRNA can lead to activation of tumor causing genes. They can also inhibit a protein that was inhibiting a cancer causing gene leading to cancer
What is the role of DNA methylation in epigenetics?
It is involved in the regulation of genes. It occurs at CpG islands are modified by methylation.
What are the mechanisms for lncRNA function?
flexible scaffolding, enhancer RNAs, Tumor suppressor signaling and RNA processing
What is the mechanism of X-chromosome inactivation?
On the activated strand T six is methylated. The inactive T six is not methylated and works with CTCF which allows Xist to work. XIST, noncoding RNA expressed by the X-chromosome to be inactivated. Binds to nonspecific DNA seq in the center and spreads.
What is the role of acetylation in cancers?
Decreased acetylation of histones can lead to no transcription of needed protein that may act as tumor suppressor
Mammalian promoters contain high levels of what?
CpG islands so they can be turned on and off by methylation
Adding an acetyl group to a histone does what?
Removes the positive charge from the lysine and decreases the affinity of the histone for the DNA
What is the clonal genetic model of cancer?
How is XIST blocked on the active X chromosome?
It is blocked by TSIX which is methylated. The inactive X will have an unmethylated Tsix leading to interaction with CTCF
