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Molecules to Medicine > Environmental Effects & Epigenetics > Flashcards

Environmental Effects & Epigenetics Flashcards

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Organic Chemistry 101 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
Q

What are enhancers

A

DNA sequences up and downstream of a gene which recruit transcription factors to bind to them

26
Q

What decides whether mRNA will be produced or not

A

Bound transcription factors (gene regulatory proteins), by deciding if RNA polymerase is active or not

27
Q

What kind of factors do transcriptional factors respond to and give examples

A

Environmental signals, e.g. Hormones, stress, nutritional signals

28
Q

What are nucleosomes

A

Basic units of eukaryotic chromosome structure. Globular in shape with a total of 140bp of DNA wrapped around it twice.

29
Q

What are nucleosomes made up of

A

8 histones (histone octamer), 2 of each of H2A, H2B, H3 & H4

30
Q

What in a nucleosome neutralises the negative charge of the DNA

A

High numbers of arginine and lysine amino acids

31
Q

What are histone tails made of and what do they have on them

A

Histone tails are made up of amino acids, the tails also have chemical tags on them

32
Q

What catalyses the addition of chemical tags to histone tails and when does this occur

A

The addition is catalysed by enzymes, this happens after translation when the amino acid sequence has been produced

33
Q

Give examples of chemical tags on histone tails

A

Acetyl, methyl

34
Q

What can chemical modifications to histone tails also act as

A

regulatory information which determines if genes attached to them should be on or off

35
Q

What will a simple mutation in the sequence of histone tails result in

A

Cell death as the tails are highly conserved

36
Q

Give an example of how enzyme families might modify histone tails

A

One enzyme will add tags whilst the other removes them. For example, Histone Acetyl Transferases and Histone De-acetylases

37
Q

Give examples of how environmental factors can determine if histone tails are acylated or not

A

Diet and medication can act as enzyme inhibitors,

38
Q

What is epigenetic therapy

A

Using drugs that modify enzymes that are involved in modifying histone tails to control whether genes are on or off

39
Q

How can open confirmation allow RNA polymerase to have easy access to genes

A

Acetyl histones will not be able to pack closely together, transcription factors will be able to bind more easily to enhancers

40
Q

What causes heterochromatin formation

A

Silencing of genes

41
Q

What types of cancers can epigenetic therapy treat

A

Haematological cancers

42
Q

Give a random (non-environmentally caused) example of epigenetics

A

X-inactivation - Females have 2 X chromosomes
Males have one X and a small gene-poor Y

43
Q

What is dosage compensation

A

Biology equalising the amount of gene product that comes whether you have one or two copies of the X chromosome

44
Q

How does dosage compensation happen in female mammals

A

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
Q

State 3 facts about X inactivation

A
  • It is random
  • It occurs in the inner cell mass of the blastocyst
  • It is an example of heritable epigenetic state
46
Q

What is an example of long-term chromosome silencing

A

X inactivation

47
Q

What are the 2 ways that gene activity can be affected by environmental factors

A
  • Gene specific transcription factors
  • Epigenetic mechanisms

Molecules to Medicine (6 decks)

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