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Dentistry Module 4 > Biochem > Flashcards

Biochem Flashcards

1
Q

What are the 5 levels of gene expression?

A
  1. Genome
  2. Transcription
  3. RNA processing and nuclear export
  4. Translation
  5. Post translation
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2
Q

DNA and protein are complexed together to form what?

A

Chromatin

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3
Q

Modifications of DNA that switch specific gene expression on/off

A

Epigenetic mechanisms

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4
Q

What is the fundamental reaction in RNA synthesis?

A

Formation of phosphodiester bonds

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5
Q

How does RNA synthesis majorly differ from DNA synthesis?

A

RNA synthesis does not require a primer

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6
Q

What are promotors?

A

DNA sequences upstream ( in front ) of the coding sequence

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7
Q

What are non-coding RNA’s also known as?

A

RNA interference RNAi

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8
Q

What does the term “cancer-critical” refer to?

A

All genes whose alteration contributes to, causing or evolution of, cancer by driving tumour development

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9
Q

The study of how behaviour and environment cause changes affecting the way genes work

A

Epigenetics

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10
Q

The development of secondary malignant tumour at a distant site from primary cancer origin

A

Metastasis

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11
Q

What are the two main classes of cancer-critical genes?

A
  1. Proto-oncogenes
  2. Tumour-suppressor Genes
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12
Q

What mutation drives proto-oncogenes towards cancer?

A

A gain-of-function mutation

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13
Q

Mutant, overactive or over-expressed forms of proto-oncogenes are known as?

A

Oncogenes

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14
Q

What mutation drives tumour-suppressor genes towards cancer?

A

Loss of function mutation

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15
Q

Give an example of a tumour suppressor gene

A

TP53

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16
Q

Define loss of function

A

Generally refers to the tumour suppressor genes, where loss of function leads towards cancer development

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17
Q

Define gain of function

A

Generally referees to a situation where gain of function leads towards cancer development. For example, oncogenes.

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18
Q

What three key pathways are often found to be damaged in tumours?

A
  1. P53
  2. Rb
  3. RTK/Ras/PI3K
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19
Q

What is the role of the p53 pathway?

A

Genes within the pathway regulate responses to stress and DNA damage

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20
Q

What is the role of the Rb pathway?

A

Involved in initiation of the cell division cycle

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21
Q

What is the role of the RTK/Ras/PI3K pathway?

A

Transmits signals for cell growth and division from the outside of the cell into the cell

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22
Q

What type of gene is p53?

A

Tumour suppressor gene

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23
Q

What gene encodes p53?

A

TP53

24
Q

What are the key functions of p53?

A
  • activation can result in cell cycle arrest, loss of cell power/growth and apoptosis
25
Q

What enzyme targets p53 for degradation?

A

E3

26
Q

What is the protein TAG that is attached to proteins, which are targeted for degradation?

A

Ubiquitin

27
Q

A rare childhood tumour in the neural precursor cells of the retina?

A

Retinoblastoma

28
Q

What type of mutation, on what chromosomes, results in retinoblastoma?

A

Deletion at specific region of chromosome 13

29
Q

What is the role of the Rb gene?

A

Encodes the Rb protein

30
Q

Define oncogenes

A

Genes that encode proteins that have the ability to cause cellular transformation

31
Q

What is the result of this over activity:

  • deletion or point mutation in coding sequence
A

Normal amounts of hyperactive protein

32
Q

What is the result of this over activity:

  • mutation in the regulatory region of the gene
A

Normal protein overproduced

33
Q

What is the result of this over activity:

  • gene amplification
A

Normal protein greatly overproduced

34
Q

What are the results of this over activity:

  • chromosome rearrangement
A

Changes to regulatory region that result in:

normal protein overproduced
OR
alters the protein coding region causing transcribed gene (hyperactive protein)

35
Q

What is the function of the Ras protein?

A

Transmit signals from cell surface receptors into the cell

36
Q

What is the type of mutation associated with Ras oncogenes?

A

Point mutation

37
Q

What pathway is critical for cell growth control?

A

PI3/Akt/mTOR

38
Q

How can the complete DNA sequence of cancer cell genome be easily obtained?

A

Exome analysis

39
Q

What are the two ways that cells communicate with each other?

A

Electrical or chemical communication

40
Q

Which type of cell communication is very fast and depends upon the presence of gap junctions for information to pass from one cell to another?

A

Electrical communication

41
Q

Which type of cell communication is the major form of information transfer between cells, where one cell releases a stimulus which alters the activity of another cell?

A

Chemical communication

42
Q

In order to trigger a response, where must cell signals be transmitted?

A

Across the cell membrane

43
Q

Name five types of signalling molecules

A
  1. Growth factors
  2. Hormones
  3. Extracellular matrix molecules
  4. Drugs
  5. Chemicals
44
Q

Through what mechanism do most receptors relay information in cell signalling?

A

Phosphorylation

45
Q

What group of enzymes are responsible for phosphorylation?

A

Kinases

46
Q

When cell communication goes wrong, what is the result?

A

Disease

47
Q

Give an example of a disease resulting from loss of a signal

A

Type 1 diabetes- pancreatic cells that produce insulin are lost

48
Q

Give an example of a disease resulting from an inability for signal to reach target

A

Multiple sclerosis -protective wrappings around nerve cells in CNS are destroyed, effected nerve cells can no longer transmit signals

49
Q

Give an example of of a disease resulting from a target ignoring the signal

A

Type 2 diabetes- cells lose ability to respond to insulin

50
Q

Give an example of a disease resulting from too much signal being transmitted

A

Brain damage by excitotoxicity- occurs after stroke due to high concentrations of glutamate being released by dying cells

51
Q

Give an example of a disease resulting from multiple breakdown of signals

A

Cancer

52
Q

What do many disease treatments rely on?

A

Cell signalling

53
Q

What are the six hallmarks of cancer?

A
  1. Sustaining proliferative signalling
  2. Evading growth suppressors
  3. Activating invasion and metastasis
  4. Enabling replicative immortality
  5. Inducing angiogenesis
  6. Resisting cell death
54
Q

What are the two most common growth factors in oral cancer?

A
  1. Epidermal growth factor (EGF)
  2. Transforming growth factor alpha (TGF- alpha)
55
Q

Which growth factor is most overexpressed (80-90%) in oral cancer?

A

Epidermal growth factor (EGF)

56
Q

What growth factor family plays an important role in angiogenesis?

A

Vascular endothelial growth factor (VEGF)

57
Q

What process is absolutely necessary for the proliferation and metastasis of solid tumours?

A

Angiogenesis

Dentistry Module 4 (20 decks)

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