BMS3020 L7 Introduction to Epigenetics 5/11/18
BMS3020 CHRONIC DISEASE
LECTURE 7 – Introduction to Epigenetics
Epigenetics Definition:
“On top of, in addition to, genetics. Heritable changes in gene expression that are
not a consequence of changes in the DNA sequence.”
- When and when not to express genes like a set of instructions, which produces a
multicellular organism.
- This is not genetics as in the genetic code itself, but rather the study of biological
mechanisms that modify gene expression, causing changes in an organism.
- Inheritance through cell generations: Two daughter cells produced when one parent cell
divides (mitosis) will have the same epigenetic pattern as parent cell which allows
maintenance of the same cell type e.g. B lymphocytes
- No inheritance through people generations: Epigenetics isn’t
passed on through people generations i.e. changes in person’s
epigenetics are not passed onto to offspring’s genome as
epigenetic system is reset during early development (rare
exceptions discussed later)
- Therefore, epigenetics can affect chronic disease in a sustained
cell type but does not affect
inherited diseases which is passed down generations as it isn’t
inherited through germline
- Epigenetics is much more easily changed than the genome –
it can be modified, environmentally (exposure, diet etc.) and
pharmacologically through drugs
- May have a role in chronic disease as it influences likelihood of
getting chronic disease and also as a way of treating/preventing the disease as you can
change the epigenetics back to the original
What are the Epigenetic Markers?
1. DNA methylation – covalent modification of the DNA itself
2. Histone modifications – histones are globular proteins around which DNA is wound, they
have tails with amino acids that can be modified in variety of ways – changing the
functioning of that DNA
3. miRNA – are not epigenetic markers, nothing inheritable about micro-RNA
DNA Methylation
Only commonly occurring covalent modification of DNA and occurs only at cytosine bases,
specifically at the 5 position of the cytosine ring
- 5-methylcytosine can also be
known as the fifth base of
DNA – just over 1% of
genome is made up of it
1
BMS3020 CHRONIC DISEASE
LECTURE 7 – Introduction to Epigenetics
Epigenetics Definition:
“On top of, in addition to, genetics. Heritable changes in gene expression that are
not a consequence of changes in the DNA sequence.”
- When and when not to express genes like a set of instructions, which produces a
multicellular organism.
- This is not genetics as in the genetic code itself, but rather the study of biological
mechanisms that modify gene expression, causing changes in an organism.
- Inheritance through cell generations: Two daughter cells produced when one parent cell
divides (mitosis) will have the same epigenetic pattern as parent cell which allows
maintenance of the same cell type e.g. B lymphocytes
- No inheritance through people generations: Epigenetics isn’t
passed on through people generations i.e. changes in person’s
epigenetics are not passed onto to offspring’s genome as
epigenetic system is reset during early development (rare
exceptions discussed later)
- Therefore, epigenetics can affect chronic disease in a sustained
cell type but does not affect
inherited diseases which is passed down generations as it isn’t
inherited through germline
- Epigenetics is much more easily changed than the genome –
it can be modified, environmentally (exposure, diet etc.) and
pharmacologically through drugs
- May have a role in chronic disease as it influences likelihood of
getting chronic disease and also as a way of treating/preventing the disease as you can
change the epigenetics back to the original
What are the Epigenetic Markers?
1. DNA methylation – covalent modification of the DNA itself
2. Histone modifications – histones are globular proteins around which DNA is wound, they
have tails with amino acids that can be modified in variety of ways – changing the
functioning of that DNA
3. miRNA – are not epigenetic markers, nothing inheritable about micro-RNA
DNA Methylation
Only commonly occurring covalent modification of DNA and occurs only at cytosine bases,
specifically at the 5 position of the cytosine ring
- 5-methylcytosine can also be
known as the fifth base of
DNA – just over 1% of
genome is made up of it
1
