eukaryotes use transcription factors to control gene expression
what is the promoter of DNA?
a section of DNA upstream of the coding region that is the binding site for proteins that control the expression of the gene
what proteins control the expression of a gene?
RNA polymerase, transcription factors
DNA can be chemically modified by the addition of methyl groups
histone proteins can be chemically modified by the addition of acetyl
what is an organisms epigenome?
all the chemical modification to all the histone proteins and DNA in
epigenetic involves heritable changes in gene function, without changes to the DNA base sequence
changes to the epigenome are caused by changes in the environment
when histones are acetylated, the chromatin is less condensed, so the transcriptional machinery can access the DNA, allowing the genes to be transcribed
when acetyl groups are removed from the histones, the chromatin becomes highly condensed and genes in the DNA can't be accessed by the transcriptional machinery, the genes aren't able to be transcribed
DNA in human tumour cells have changes in DNA methylation and histone acetylation which causes tumour suppressor genes to be silenced and oncogenes to be activated leading the the formation of tumours
what does RNAi stand for?
RNA interference
RNAi is a form of post-translational modification which occurs in the cytoplasm
RNAi is sequence specific silencing of gene expression and therefore can be very precise in silencing certain genes
in eukaryotes translation of the mRNA produced from target genes can be inhibited by RNAi
all tumours can cause harm to the body by?
damaging the organ it's located on, causing blockages or obstructions, damaging organs by exerting pressure
malignant tumours are cancerous
benign tumours are non-cancerous
cancers start when the expression of genes that control cell division become mutated
oncogene is the mutated gene that cause cancer to form
tumour suppressor gene are normal genes that code for proteins that regulate the cell cycles
hypermethylation of DNA causes transcription inhibiting proteins to bind to the DNA
proton-oncogene are normal gene that code for proteins that regulate cell growth and cell differentiation
mutations of proton-oncogenes to produce oncogenes can occur through inversion or translocation mutations