Lecture 7- Epigenetics: link between genes and environment Flashcards
What are the genes and epigenetics in the music analogy?
- Genes = instruments
- Musicians = epigenetics
What makes identical twins different?
- Identical DNA, different personalities
- Difference = epigenetics
- “above genetics”
What makes cells different?
- Identical DNA, different cell types
- Difference = epigenetics “above genetics”
What do epigenetisc do?
- Epigenetics changes the activity of genes in response to environment
- e.g. Queen Bee= so different eventough only difference is the royal jelly bath during development
- e.g. plants= flower better if cold winter= people also different depending on when born (weather, season)
What is epigenetics?
- Epigenetic ‘marks’ can act as:
- A volume control for genes
- A way to organise our the 2 metres of DNA in every cell.
- A way to develop different cells with the same DNA
- A way for you to adapt to your environment
What is an epigenetic mark?
- A small molecule:
- Methyl
- Acetyl (COCH3)
Where do the marks go?
• Onto DNA (CpG methylation)
• Onto the proteins that package DNA
(histones)
-DNA methylation can go onto DNA, associated with reduction in gene activation, methyl group onto histone tails (that is how they can attach)
How do the marks get there?
- Sequence-specific recruiting factors • Protein transcription factors
- Non-coding RNA
What is the epigenetic code?
-the four ‘R’s: Recruiters, wRiters, Readers and eRasers
1• Sequence-specific factors (recruiters) bind to DNA(= • Transcription factors (proteins)
• Non-coding RNAs)
2.• Epigenetic modifiers (writers) recruited 3. Epigenetic marks (re-)written
4.Epigenetic marks bound (“read”) by complexes of proteins.
5.• Epigenetic marks erased
How does chromatin control gene activity?
1.• Loose chromatin structure • Less DNA methylation
• “Active” histone marks
• Genes turned up
2.• Tight chromatin structure • More DNA methylation
• “inactive” histone marks
• Genes turned down
- it is a reversible process= the epigenetic process(previous slide)
- combination of loss of methylation = more active gene expression
- combination of a specific mark and physical structure (active marks= cause chromatin to be loose, inactive marks= tight)
What is the importance of histones in the genetic code?
histone (protein) wrapped by DNA, chemcial tags and tail
= epigenome
=shapes teh physical structure of the genome
-if tight= not read, not atcive gene
-loose= active
-epigenetic is flexible
What is the lick a rat study?
compare rats= licked and groomed offspring and the ones neglected= grew to be nervous
- stress pathway affected, a GR gene (glucocorticoid gene)
- there is evidence that a similar thing happens in humans= when abused as children
- also PTSD
- also those in womb
- when smoking= babies have less methylation
- plastic after birth and in the womb, we never lose the sensitivity completely
Can epigenetics be reversed?
- yes, by diet or drugs
- can still be affected by the environment= can reverse the effect of an early environment, possibly
- yoga, mindfulness, meditation= change genes too!
What in our environment can change epigenetics?
1.The good • B group vitamins • Soy • Broccoli • Tea • “Good” bugs
2.The bad
• Stress
• Fungicides & pesticides • Fire retardants
• Plasticisers (BPA) • “bad” bugs
- broccoli= contains many epigenetic molecules, the same case with most vegetables and fruit
- about 1.5 kg= of bacteria in our body, we feed them through breast milk= short chain oligosaccharides for the bacteria
How did the mice fathers influence the offspring?
- Male rats fed a high fat diet fathered obese sons.
- Male mice fed a low protein diet had offspring with lower levels of cholesterol.
- Male pigs fed an “epigenetic diet” had leaner grandchildren.
- All were accompanies by epigenetic changes
