Gene expression Flashcards
What are stem cells
Undifferentiated cells that become specialised
Totipotent
Can become any type of body cell
From early stage embryos
Pluripotent
Can become most cells
Taken from embryos
Used for human disorders
Multi and unipotent
Can become a small amount of cells
From mature mammals
Induced pluripotent
Produced from adult somatic cells using TFs
Genes switched off to make specialised cells are switched back on
Control of transcription
Transcription factors bind to genes turning them on and beginning transcription
What is oestrogen and what does it do
Steroid hormone
Binds to receptor on TFs
Changes its shape making it complementary to DNA
What is epigenetics
Heritable change in gene function without changing base sequence
Caused by environmental changes
Methylation of DNA
Increased methylation -attach to cytosine base -prevents TF from binding -attracts proteins to condense histones -preventing transcription Heterochromatin
Acetylation of DNA
Decreased acetylation of histones inhibits transcription
-acetyl groups removed, histones become more positive
-become more attracted to phosphate groups on DNA
-DNA and histones become more strongly associated
Euchromatin
RNA interference
RNA gets destroyed before translation
SiRNA fuses with enzyme
Binds to mRNA via complementary bases
Cuts up mRNA
Benign tumours
Grow large and slowly
Non-cancerous because of adhesive molecules and capsule, prevents it spreading
Localised effect so can be removed as a whole
Malignant tumour
Cancerous, grow large and fast Nucleus grows large and becomes unspecialised Metastasis - tumour breaks and spreads Can develop its own blood supply Recurrence is likely
Oncogenes
Mutated proto-oncogenes
Proteins involved in initiation of DNA replication
Become permanently active
Tumour suppressor genes
Slow cell division, produces proteins causing cell death
Mutations cause these proteins not to be produced
Uncontrolled cell division
