epigenetics Flashcards
what is epigenetics idea
that environmental factors can cause heritable changes in gene function without affecting the base sequence
what is dna wrapped around
dna is wrapped around histones forming a dna histone complex
what is also added to the complex
tags which cover the complex which form an epigenome and determine the shape o dna complex
how does it determine the shape of the complex
keeps inactive gene tightly packed arrangement so that they cannot be read or Tran scripted - epigenetic silencing and those that are active are unwrapped so can be accessed by transciption factors and transcribes
how does the dna and epigenome differ
dna is fixed wheras epigenome is flexible
why is epigenome flexible
the chemical tags respond to environmental change such as diet, stress cuasing it to wrap or unwrap
what happens in early development
signals come from within the cells of the featus and nutrition is provided by the mother so form epigenome
what happens after birth
environmental factors affect the genome including hormone s
what does the environmental signal do
cause the epigenome to activatre or inhibit specific set of genes
what happens when there is an environmental signal
enviromental signal stimulates protiens to carry its message into the cell from where it is passed into the nucleas and passed in to specific protein which attahches to a specific sequence of base on dna
once attached to dan what effects can occur
acetylation of histones leading to activation or inhibition of a gene
or methylation of DNA by attracting enzymes that can add or remove methyl groups
WHAT HAPPENS WHEN THE DNA HISTONE COMPLEX IS WEAK
THE DNA IS LESS CONDENSED AND LOOSELY PACKED
What does this mean for the dna
it is more exposed so can be easily accessible by transcription factors, switch gene on and produce mrna
what happens if the dna histone is more stronger
the dna histone complex is more strong and compacted
what does this mnean for the dna
it is less accessible for the transcriptional factors so cannot innitate mrna so gene is switched off
