MTM WK5 - GENE EXPRESSION Flashcards
CELL MEMORY
ability for differentiated cell to maintain its morphology & pattern of gene expression
TERMINALLY DIFFERENTIATED CELLS
have specific pattern of gene expression (some genes turned on & some off based on type of cell they choose to become)
GENE PROMOTER REGION
- right in-front of 5-prime region (so known as a 5-prime regulatory protein)
- needed as RNA polymerase can’t recognise transcription start sites so TF’s come in & bind to promoter then recruit RNA polymerase II for transcription
ENHANCERS
control transcription rate as gene regulatory proteins bind to these enhancer regions
HOW GENE REGULATION WORKS
RNA polymerase binds to TF on promoter & just sits there until activated, many TF’s activate RNA polymerase & either start/stop transcription. Each enhancer codes for different protein
HISTONE CODE
layer of info overlaying DNA & involved in turning genes on/off (it is the chemical tags)
HOW RNA POLYMERASE CHANGES CODING SEQUENCE
identical sequence as before but it just swaps all the T’s in template strand for U’s
ACETYLATION
- acetylate by histone acetyl transferases in nucleosomes
- de-acetylated by histone de-acetylases
- decreased acetylation = increased histone charge = stronger association between DNA & histones = DNA not accessible to TF)
METHYLATION
increased methylation = tighter DNA-histone complex = inaccessible to TF
DOSAGE COMPENSATION
every human has 22 copies of each chromosome (2 alleles of each) but men have XY instead of XX. Overcome as in females, one X is inactivated early in development so effect of 2X instead of one X one Y is diminished (X-inactivation is random (Maternal or Paternal)
LESS DENSE VS MORE DENSE IN IMAGINE
- more dense shows up as light (as absorbs more as is calcified)
- soft tissue/ less dense is dark
