Revision Flashcards
(32 cards)
define neoplasm
an abnormal mass of tissue the growth of which exceeds and is uncoordinated with that of the normal tissues and persists in the same excessive manner after cessation of the stimuli that evoked the change (at this point growth becomes irreversible)
what is promoter gene methylation associated with
gene silencing - plays important role in maintaining cell types.
what enzymes carry out DNA methylation
DNA methyltransferases (DNMT1, DNMT3 a and b)
where do CPG islands occur
in promoter regions of genes
what do DNMT3 a and b do
cause denovo methylation of DNA allowing cells to differentiate into different cell types during embryo development
what does DNMT 1 do
maintains methylation following differentiation and is active during cell division there after
are cpg islands in promoter regions typically methylated or unmethylated
unmethylated
what so promoter regions of genes contain
regulatory elements that control the transcription of genes
which base does methylation affect
C (adds CH3)
what do TET enzyme
regulate DNA de methylation
what happens to methylation in cancer
is disregulated
get hypermethyation of CPG islands in promoter regions causing tumour suppressor gene inactivation
also get hypomethylation across entire genome deregulating entire epigenomic landscape
=extensive hypomethylation and selective hypermethylation
what does extensive hypomethylation in cancer cause
chromosomal instability
what is the warburg effect
modified metabolism is cancer cells- favour anaerobic glycolysis in the cytoplasm
what are the basic stages of cancer development
normal epithelium hyperplastic/ hyperrpoliferative dysplastic carcinoma metastasis
what are mitogens
growth factors
usually present in cancer cells
how do cancers prevent telomere erosion
reactivate teleomerase
what is ameoboid movement
crawling like movement of cells via temporary cytoplasmic projections (pseudopodia)
required for invasive growth of cancer, give ability to break neighbouring E cadherin connections
what are cadherins
cell adhesion molecules
cadherin E allows cell to cell adhesion in epithelium
cadherin N promotes cell migration
what vascular spaces can cancers invade
perineural lymphatics
lymphatics
vascular
where does cancer that invade veins go
liver and lungs
what does TNm stage for
tumour- size, anatomical boundaries
nodes- number, size and location
mets- present or not
what direction is the coding strand of DNA
5-3
which direction is RNA built up
3-5 but comes out 5-3
what is a motif
a DNA sequence that is a signal to the cell
