Epigenetics Flashcards
What is a genome?
A complete set of inherited genetic information.
What is mosaicism?
The property or state of being composed of cells of two genetically different types.
What are single cell genomics?
Map the transcriptomics of the whole body.
What is a phenotype?
Genes interacting with the environment for presenting characteristics?
Why do the genotype and the phenotype differ?
Because the genome can be read differently to give a different phenotype.
What makes a genome more complex?
Introns
What is the phenotype controlled by?
Gene regulation
What is the regulatory DNA?
Nucleic acid sequence capable of either increasing or decreasing expression of a gene
What is the role of regulatory DNA?
Operate as ‘post codes’ for the assembly of protein complexes that control the rate of transcription
How is a regulatory complex formed?
Chromatin loops over to joining enhancers and promoters
What happens when you replace the DNA in a fibroblast?
When MYOD is inserted it becomes a muscle cell.
Why does inserting MYOD into a fibroblast change it’s cell type?
Activates a present but not functional Transcription factor allowing for new information to be transcribed.
What are epigenetics?
Heritable changes in phenotype or gene expression caused by mechanisms other then changes in the underlying DNA sequence
What are the 2 types of chromatin?
Heterochromatin
Euchromatin
What is heterochromatin?
Closed chromatin conformation , no transcription
What is eurochromatin?
Open chromatin conformation, transcription occurs
How does chromatin open?
Histone Lysine Acetylation Relaxes (Opens) Chromatin
Why does transcription stop when chromatin is deacetylated?
Tails stick out and can be seen by enzymes.
How does acetylation change chromatin position?
Positive-charged lysines are attracted to negative-charge DNA
Acetylation masks the negative charge which repels DNA to “open” chromatin.
What else can histone lysine acetylation do?
Write
Erase
Read
How is histone lysine acetylation used to read DNA?
Binds to the acetyl group epigenetic markers allowing for the enzyme to attach.
What happens to histone acetylation in cancer and why is that important?
Becomes dysregulated, and this allows for it to be a target for drugs.
How is lysine methylation a gene regulator/
Doesn’t turn the gene off completely however but can speed up or slow down DNA replication or expression.
What is HMT?
Histone methyltransferase
What is HDM?
Histone demethylase
What is the problem with jumping genes?
Must be switched off because they replicate like crazy
What are CpG regions?
Promotor regions which can be used as an epigenetic platform.
What happen when aberrant methylation occurs at CpG islands?
Cancer
What is the role of DNA methyltransferases (DNMTs)?
Writers
What is the role of Ten-eleven translocation (Tet) proteins?
Erasers
What is the role of Methyl-Domain binding (MBDs) proteins?
Readers
What is the role of CG binding proteins?
Readers
What is the agouti mouse?
Has unmethylated DNA which leads to the mouse being yellow and obese and later gets cancer and dies much younger.
What vitamin is used for methylating DNA?
Folic acid
What reduces the methylation in DNA?
Bisphenol A
What is somatic cell divsion?
Daughter cells inherit their DNA methylome.
What is somatic cell division regulated by?
The maintenance enzyme DNMT1.
What is the advantage of somatic cell divison?
Enables the regeneration of specific cell types
What is the germ-plasm or Weismann Barrier theory?
Somatic cells do not function as agents of heredity.
The flow of genetic information is one-way from ger plasm to soma, this cannot be reversed.
What kind of epigenetic inheritance is there?
Intergenerational transmission
Multigenerational transmission
Transgenerational transmission
What is intergenerational transmission?
Exposure leads to change in phenotype in children.
What is multigenerational transmission?
Exposure leads to changes in phenotype in children and grandchildren.
What is transgenerational transmission?
Exposure leads to changes in phenotype in children, grandchildren, and subsequent generations to exposed to initial insult.
Does the epigenetic transmission of phenotypes change the gene sequence?
NO
What are the developmental epigenetic barriers?
Two developmental phases where DNA methylation is “erased” and reprogrammed
What are the 2 developmental phases where DNA methylation is “erased” and reprogrammed?
When primordial germ cells are being proliferated and are migrating to become oocytes.
When the zygotes divide after fertilization.
How is DNA methylome analysis carried out?
Laser dissection
gDNA extraction
Bisulphite conversion to reveal mCpGs
Deep sequencing
What is bisulphite sequencing?
Identify and quantify methylated DNA.
