Bio - Epigenetics

Question 1

DNA

Answer 1

Info used to create proteins.

Question 2

Gene

Answer 2

Section of DNA that enables a specific function.

Question 3

Transcription

Answer 3

Reading of info in DNA/genes by enzymes.

Question 4

Histones

Answer 4

Protein that forms ‘bundles’.

Question 5

Methylation

Answer 5

A methyl group suppresses gene expression by closing the histone structure.

Question 6

Acetylation

Answer 6

A acetyl group promotes gene expression by opening the histone structure.

Question 7

Reader

Answer 7

Proteins that stimulate/change activity by binding (neurotransmitters).

Question 8

Writer

Answer 8

Enzymes that add methyl or acetyl groups.

Question 9

Eraser

Answer 9

Enzymes that remove methyl or acetyl groups.

Question 10

Genotype

Answer 10

The info present in DNA.

Question 11

Phenotype

Answer 11

The result of the expression of your DNA in the environment.

Question 12

Diathesis-stress

Answer 12

A model of disease that sees nature and nurture as interacting forces.

Question 13

Describe how DNA is read

Answer 13

• Each part codes for its own proteins and a single string can have many outcomes depending on what parts are selected.
• The DNA is read (transcribed) by specialised enzymes in the same order every time, but parts we don’t need right now are ‘skipped over’.
• The result is RNA - this is then translated into proteins.
• The DNA must open up in order for enzymes to ‘read’ the code.
• This allows the RNA to be put together, mimicking the info in the DNA strand (gene) before being capped at both ends.
• DNA that’s able to open and be read in this way allows normal functioning.

Question 14

The extent to which the genes are accessible (whether the DNA is ‘open’) is controlled by what?

Answer 14

Methyl groups - methylated genes cannot be read - this chemical causes genes to be ‘skipped’ when surrounding genes are transcribed.

Question 15

What is the DNA coiled around?

Answer 15

Structures called histones.

Question 16

What is caused as a result of the fact that methylated genes cannot be read?

Answer 16

This chemical causes genes to be ‘skipped’ when surrounding genes are transcribed.

Question 17

What is epigenetics?

Answer 17

The study of gene replication by methyl modifications.

Question 18

What do methyl groups do?

Answer 18

Modify the transcription of DNA without changing it.

Question 19

What can cause methyl groups to be added to genes?

Answer 19

Environmental influences (e.g. environmental stress, dietary choices, UV light, drugs, chemical exposure, exercise or lack of exercise).

Question 20

What environmental influences can cause methyl groups to be added to genes?

Answer 20

E.g. environmental stress, dietary choices, UV light, drugs, chemical exposure, exercise or lack of exercise.

Question 21

What are applications showing that environmental influences can cause methyl groups to be added to genes, causing them to become risk genes?

Answer 21

`We see ‘risk genes for psychiatric disorder but the concordance rate is never 100%.

• E.g. dysfunctional COMT or SERT are risk genes for OCD, but we all have these genes.
• Even if you have two parents with OCD, you might not get it - this will depend on the environment you grow up in, which will modify the genes you inherit.

Question 22

What proteins/enzymes will cause modifications to genes?

Answer 22

Writers, readers and erasers.

Question 23

What health issues are linked to the process of gene modification caused by writers, readers and erasers?

Answer 23

E.g. cancer, autoimmune diseases, mental disorders and diabetes.

Question 24

Is nature or nurture the cause of the development of illnesses?

Answer 24

Genes and the environment both contribute to the development of illnesses.

Question 25

What does the environment do to our genes?

Answer 25

It changes the expression of genes to produce a phenotype that is different from the genotype.

Many environmental factors can contribute to this.