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gene expression/epi
genetics exam 2
| Question | Answer |
|---|---|
| What is the default of a gene? | turned off |
| what are the three process that cross talk? | methylation, histone remodeling, mRNAi |
| methylation | addition or removal of methyl groups to or from bases in DNA |
| What is methylation associated with? | decreased gene expression |
| How can methylation repress transcription? | by binding to transcription factors of DNA |
| What type of relationship is there between degree of methylation and degree of expression? | inverse |
| X chromosome in female cells are... | heavily methylated= not expressed |
| Methylation patterns are tissue specific and once established are... | inevitable for all cells of that tissue |
| What are proper methylation patterns essential for? | mammalian development, important in long-term silencing of genes |
| What is methylation involved in the development of? | heterochromatin and in binding proteins that modify histones |
| Where does DNA methylation occur frequenctly | on the cytosine of CG islands |
| What type of changes are histone remodeling? | epigenetic changes that occur on the histone tails |
| components of histone remodeling | HATS and HDACs |
| histone remodeling | modification of chromatin structure that controls how tightly or loosely DNA is wrapped around histones |
| RNAi | RNA interference, post transcriptional regulatory mechanism |
| What is RNAi regulated by? | siRNAs and miRNAs |
| what is the main function of a micro RNA? | coordinated reduction in gene expression |
| RISC | interfering micro RNA causes degradation stopping protein production |
| RITS | interfering micro RNAs causing silencing of mRNA stopping protein production |
| What does DICER enzyme do? | cuts interfering DNA into a single strand |
| What does DICER enzyme cleave precursors into? | siRNAs and miRNAs |
| What did early prenatal exposure from the dutch famine associate with? | hypomethylation of IGF2 |
| IGF2 | growth factor key in human growth, maternally imprinted with paternal gene expressed |
| HATS (histone acetyltransferase enzyme) | catalyzes histone acetylation |
| What is HATS associated with? | increased transcription, opens chromatin |
| HDACS (histone deactylation enzymes) | result in tight coiling and a closed chromatin structure |
| imprinting | only inherit one copy, depending on the gene, either the copy from the mom or dad is epigenetically silenced |
| What does silencing in imprinting usually happen through? | the addition of methyl groups during egg or sperm formation |
| What happens if both alleles are expressed, one when is supposed to be implanted? | that cell may develop into a cancer |
| What is Prader Willi caused by? | deletion or inactivation of genes on the paternally inherited chromosome 15 |
| Prader Willi | developmental delay, uncontrollable eating, obesity, poor muscle tone, intellectual disability |
| What is Angelman syndrome caused by? | deletion or inactivation of genes on the maternally inherited chromosome 15, inactivation of maternal UBE3A |
| Angelman syndrome | difficult to diagnose: developmental delay, speech delay, always happy- puppet like laughing always |
Created by:
camrynfoster