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Molecules to Medicine > Environmental Effects & Epigenetics > Flashcards

Environmental Effects & Epigenetics Flashcards

1
Q

What is a phenotype

A

The observable characteristics of an individual. Phenotypes are a combination of genotype and environment.

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2
Q

What are alleles

A

Different versions of the same gene

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3
Q

What are housekeeping genes

A

A set of structural genes expressed in all cell types. They are essential for life

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4
Q

Give examples of some proteins that housekeeping genes code for (4 exaples)

A
  • Histones
  • RNA Polymerase
  • Tubulin
  • Pyruvate kinase
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5
Q

What determines cell identity

A

The expression of cell specific genes

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6
Q

What are cell specific genes

A

Genes that are not switched on in all cells. They code for proteins that allow a cell to carry out specialised functions

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7
Q

Give an example of a cell specific gene that is turned on in skeletal muscle

A

Troponin

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8
Q

What is epigenetics

A

Change in gene expression without changing the genetic code itself. It is an environmental mechanism

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9
Q

What does epigenetics allow cells to do

A
  • allows differentiated cells to maintain gene expression pattern throughout their life.
  • Allows multiple phenotypes to be generated from the same genotype.
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10
Q

What are the 6 different levels that gene regulation is controlled at

A
  • Transcriptional control
  • RNA processing control
  • RNA transport and localisation control
  • Translation control
  • mRNA degradation control
  • Protein activity control
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11
Q

What is the most prominent level of gene control (determining what proteins are produced)

A

Level of transcriptional control

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12
Q

What level of gene control splices the DNA by removing introns

A

RNA processing control

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13
Q

What level of gene control requires ATP for active transport

A

RNA transport

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14
Q

At what level of control will the protein not be generated if the mRNA is degraded

A

Translational control

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15
Q

LEVEL OF GENE CONTROL 5 Q

A

LEVEL OF GENE CONTROL 5 A

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16
Q

At what level of control will an active protein be generated and then inactivate or vice versa

A

Protein activity control

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17
Q

What are transcriptional units made of (2 things)

A
  • Structural information
  • Regulatory sequence
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18
Q

What does structural information code for

A

proteins

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19
Q

What do regulatory sequences code for

A

instructions for gene expression

20
Q

What is the tata box and where is it found

A

It’s a gene promoter region, immediately adjacent to the coding region as a 5’ regulatory sequence

21
Q

How is transcription initiated

A

Gene transcription factors are recruited by a gene to bind to the 5’ promoter region which will recruit RNA polymerase II to initiate transcription

22
Q

What indicates where a gene starts as RNA polymerase is unable to recognise this

A

5’ regulatory sequences

23
Q

What can gene transcription factors (GFTs) do

A
  • Allow a basal level of transcription
  • Recruit RNA polymerase II
  • Allow a ‘basal’ level of transcription
24
Q

What 2 factors control rates of transcription

A
  • Enhancers
  • Gene-specific transcription factors
25
What are enhancers
DNA sequences up and downstream of a gene which recruit transcription factors to bind to them
26
What decides whether mRNA will be produced or not
Bound transcription factors (gene regulatory proteins), by deciding if RNA polymerase is active or not
27
What kind of factors do transcriptional factors respond to and give examples
Environmental signals, e.g. Hormones, stress, nutritional signals
28
What are nucleosomes
Basic units of eukaryotic chromosome structure. Globular in shape with a total of 140bp of DNA wrapped around it twice.
29
What are nucleosomes made up of
8 histones (histone octamer), 2 of each of H2A, H2B, H3 & H4
30
What in a nucleosome neutralises the negative charge of the DNA
High numbers of arginine and lysine amino acids
31
What are histone tails made of and what do they have on them
Histone tails are made up of amino acids, the tails also have chemical tags on them
32
What catalyses the addition of chemical tags to histone tails and when does this occur
The addition is catalysed by enzymes, this happens after translation when the amino acid sequence has been produced
33
Give examples of chemical tags on histone tails
Acetyl, methyl
34
What can chemical modifications to histone tails also act as
regulatory information which determines if genes attached to them should be on or off
35
What will a simple mutation in the sequence of histone tails result in
Cell death as the tails are highly conserved
36
Give an example of how enzyme families might modify histone tails
One enzyme will add tags whilst the other removes them. For example, Histone Acetyl Transferases and Histone De-acetylases
37
Give examples of how environmental factors can determine if histone tails are acylated or not
Diet and medication can act as enzyme inhibitors,
38
What is epigenetic therapy
Using drugs that modify enzymes that are involved in modifying histone tails to control whether genes are on or off
39
How can open confirmation allow RNA polymerase to have easy access to genes
Acetyl histones will not be able to pack closely together, transcription factors will be able to bind more easily to enhancers
40
What causes heterochromatin formation
Silencing of genes
41
What types of cancers can epigenetic therapy treat
Haematological cancers
42
Give a random (non-environmentally caused) example of epigenetics
X-inactivation - Females have 2 X chromosomes Males have one X and a small gene-poor Y
43
What is dosage compensation
Biology equalising the amount of gene product that comes whether you have one or two copies of the X chromosome
44
How does dosage compensation happen in female mammals
One of the X chromosomes is silenced in early development. So, both males and females have one active X chromosome. This is known as X inactivation
45
State 3 facts about X inactivation
- It is random - It occurs in the inner cell mass of the blastocyst - It is an example of heritable epigenetic state
46
What is an example of long-term chromosome silencing
X inactivation
47
What are the 2 ways that gene activity can be affected by environmental factors
- Gene specific transcription factors - Epigenetic mechanisms

Molecules to Medicine (6 decks)

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