Epigenetics

Question 1

what is the definition of epigenetics?

Answer 1

-the study of heritable modifications of the genome that do not involve changes to the DNA sequence

Question 2

how do epigenetics work?

Answer 2

-affects gene activity without changes to the DNA sequence
-it can enhance the gene or it can shut it down

Question 3

what are the two ways that epigenetic modifications can occur?

Answer 3

-DNA methylation
-histone modification

Question 4

how does DNA methylation occur?

Answer 4

-chemical group methyl is added to the base cytosine when the base C is immediately followed by the base G
-this creates a CpG sequence
-if a large enough number of these CpG sequences are methylated transcription cannot occur
-the gene is switched off

Question 5

in terms of epigenetics why are liver cells only produced in the liver and not in the skin?

Answer 5

-proteins that are associated with the liver are only produced in the liver
-this is because DNA methylation switches off the genes that code for liver proteins everywhere else in the body

Question 6

is DNA methylation permanent and what does this mean for future cells?

Answer 6

-yes
-mitosis means that these modifications can be passed from cell to cell

Question 7

how does histone modification occur? is it more or less complex that methylation and why?

Answer 7

-DNA is wrapped around 8 histone proteins
-histones can be modified through the addition of chemical groups
-it is more complex than methylation as it can occur in many different ways
-it can affect the likelihood of transcription

Question 8

is histone modification long or short term?

Answer 8

-short term