8.2 regulation of gene expression

Cards (35)

  • a stem cell is a cell that can divide an unlimited number of times
  • potency is the ability of a stem cell to differentiate into more specialised cells
  • totipotent stem cells can divide and produce any type of body cell
  • pluripotent stem cell can differentiate into any cell type found in an embryo
  • multipotent stem cells can differentiate into a few different cell types
  • unipotent cell can only differentiate into one type of cell
  • stem cells become specialised because different genes are expressed
  • bone marrow contains stem cells that can become specialised to form any type of blood cell
  • how are induced pluripotent stem cells made?
    by reprogramming specialised adult body cells so that they become pluripotent
  • what is a transcription factor?
    a protein that control the transcription of genes by binding to a specific region of DNA
  • what are the risks of using stem cells?
    Tumour formation, immune rejection, ethical concerns.
  • 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