Epigenetics

Question 1

What is Epigenetics?

Answer 1

pattern of inheritance in which a gene or chromosome is modified temporarily. changes the gene expression, function or regulate the DNA, Protein or RNA molecules WITHOUT changing the primary sequence.

Question 2

Are the changes Stable or Dynamic?

Answer 2

they can be both but they are not permanent. the resulting gene expression is not permanent.

Question 3

where do these changes occur in?

Answer 3

can be during oogenesis, spermatogenesis or early stages of embryonic development. Can be removed too!

Question 4

What are the examples of Epigenetic Regulations?

Answer 4

1. Twins - Genome are identical
2. embryogenesis in female mammals
3. Epigenetic inactive X chromosome that female inherit from parents.

Question 5

what is the reason behind chromosome inactivation?

Answer 5

nobody knows its still not yet understood but according to research it says mammals cell only allow X chromosome to stay active and deactivate the rest

Question 6

what happens to inactive ones?

Answer 6

they form barr body

Question 7

what is genome imprinting?

Answer 7

• another form of epigenetic inheritance where the gene is depended on parent sex.
• non mandelian inheritance
• permanent in somatic cells but marking of allele can be changed from generation.

Question 8

can offspring express both maternally/paternally?

Answer 8

no only one
either maternally or paternally inherited allele
(monoallelic Expression)

Question 9

what is DNA Methylation?

Answer 9

Common Epigenetic Modification
a chemical marking process that is important for genomic imprinting.

Question 10

Imprinting + DNA Methylation Process

Answer 10

A methyl group CH3 is added onto the cytosine based in DNA in the regions required for gene regulation and expression. Results in Inhibition of gene expression aka silencing gene :)

Question 11

where does Imprinting+DNA Methylation takes place?

Answer 11

either in sperm or oocyte but never in both.

Question 12

what are classical genetics controlled by?

Answer 12

Promoters
Enhancers
Protein binding sites (present in DNA sequence)

Question 13

what is an example of this regulation ? (classic genetics, genetic regulation)

Answer 13

control of expression of a cellular oncogene in cancer.

Question 14

explain what happens in control of expression of cellular oncogene?

Answer 14

normally in cells this gene is not expressed but in cancer cells it causes a mutation which changes the DNA sequence. allows the oncogene to be expressed and starts developing cancer.

Question 15

can epigenetic mechanism regulate other cellular processes too?

Answer 15

yes

Question 16

what are the difference between genetic and epigenetic regulation

Answer 16

Epigenetics dont change the DNA sequence while genetic mechanism changes the primary DNA sequence or Mutations to this sequence.
epigenetics are the changes after the regulation of genetic mechanisms.

Question 17

What are the models of Epigenetic Research?

Answer 17

1. Budding Yeast Saccharomyces Cerevisiae
2. Protozoan Tetrahymena Therophila
3. Drosophila Melanogaster - classic model
4. Arabidopsis Thaliana - plant model with considerable epigenetic mech as mammals
5. Mice - similar to human - used for embryology.

Question 18

epigenetic biological applications

Answer 18

• controls the expression of embryonic development genes
• X-chromosome inactivation
• Development of stem cells
• Differentiation of somatic cells
• Making of differentiated cells from adult stem cells and specific cell type
• Erasure + reestablishment of DNA methylation.

Question 19

Cancer related applications

Answer 19

1. age related DNA methylation biomarkers are linked with diseases.
2. Many DNA methylation biomarkers have been found to be linked with Cancer
3. many tumour suppressor genes show hypermethylation and in other cancers it shows hypomethylation.

Question 20

how exactly are epigenetic mechanisms applied in types of Cancer ?

Answer 20

1. Silencing of tumour supressor
   2 Activation of oncogenes
2. histone modifications

Question 21

what class of drugs used in Cancer Treatment?

Answer 21

Some examples -
1. DNA Methyl-transferase inhibitors
2. Histone De-acetylase inhibitors

Question 22

how does the treatment work tho?

Answer 22

Epigenetic markers linked with specific diseases.
new tools to diagnose and assess the severity of disease
therapeutic epigenetics

Question 23

Chemotherapy Drugs

Answer 23

1. Azacitidine (Vidaza)
2. Decitabine (Dacogen)
3. Vorinostat (Zolinza)
4. Romidepsin (Istodax)

Question 24

What is the mode of action of Azacitidine?

Answer 24

make genes fight cancerous cells when given at VERY low doses. also found effective for lung cancer.

Question 25

Mode of action of Decitabine?

Answer 25

treats Myelodysplasia a condition affecting the production of blood cells in bone marrow and leukaemia.

Question 26

Vorinostat

Answer 26

approved drug for treatment of immune system cancer - Cutaneous T-cell lymphoma

Question 27

Romidepsin

Answer 27

epigenetic injection like vorinostat, romidepsin

approved to treat peripheral T-cell lymphoma in patients who have received atleast one prior therapy.

Question 28

Causes of Cancer?

Answer 28

Heredity
Immunology
Hormones (internal factors)
External factors - chemicals, viruses, diet and radiation.
Environmental factors - chemicals like air pollutants, asbestos.
Lifestyle factors - diet, smoke, alcohol, direct sun exposure.
Dietary factors - 35% of all human cancer.
Cigarette smoke - 30%

Question 29

What are Carcinogens

Answer 29

Molecular process by which cancer develops. agents.
classified as genotoxic or nongenotic (epigenetic)

Certain viruses can also act like carcinogens by interacting with DNA