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Principles of Disease KR > Mixed Questions > Flashcards

Mixed Questions Flashcards

1
Q

Mutations in what genes can often lead to breast cancer development?

A

BRCA1 and BRCA2 - tumour suppressor genes

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2
Q

Mutation of what gene is the most common cause of Cystic Fibrosis?

A

F508

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3
Q

What kind of mutation is it that occurs on the F508 gene to cause cystic fibrosis?

A

deletion - results in loss of the amino acid phenylalanine at the 508th position on the protein

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4
Q

What is ‘X’ linked inheritance?

A

sex linked inheritance

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5
Q

What are the 4 mechanisms of structural abnormalities of genes (mutations)?

A

deletions
insertions
inversions
translocations

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6
Q

What are the 2 types of translocations?

A

Robertsonian

Reciprocal

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7
Q

What is Robertsonian translocation?

A

fusion of 2 afrocentric chromosomes - unbalanced

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8
Q

What is reciprocal translocation?

A

involves breaks in 2 chromosomes with the formation of two new derivative chromosomes

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9
Q

When is a reciprocal translocation balanced?

A

if the zygote inherits both chromosomes involved in the translocation

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10
Q

What is a ‘silent’ mutation?

A

the right amino acid is still coded for despite change in base

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11
Q

What is a ‘missense’ mutation?

A

change in base leads to change in amino acid coded for

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12
Q

What is a ‘nonsense’ mutation?

A

protein is stunted due to stop amino acid being coded for

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13
Q

What is a ‘frameshift’ mutation?

A

deletion/insertion so every amino acid coded for after that will be wrong

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14
Q

What are the 2 types of point mutations?

A

transitions i.e purine to purine

transversions i.e purine to pyramidine

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15
Q

What does the p53 gene do?

A

codes for proteins that will:

facillitate DNA repair

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16
Q

What are mismatch repair genes?

A

they are ‘spellcheckers’ - they repair base pair mismatches

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17
Q

What happens when mismatch repair genes mutate?

A

can no longer carry out function - DNA changes

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18
Q

What can mismatch repair failure lead to?

A

microsatellite instability

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19
Q

What is meant by micro satellite instability?

A

is the phenotypic evidence that MMR is not working properly

cells with abnormally functioning MMR tend to accumulate errors

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20
Q

What is a trisomy?

A

having an extra copy of a particular chromosome therefore having 3

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21
Q

What 3 syndromes are examples of the consequences of trisomy?

A

Down’s
Edward’s
Patau’s

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22
Q

Which trisomy causes Down’s syndrome?

A

trisomy of chromosome 21

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23
Q

Which trisomy causes Edward’s syndrome?

A

trisomy of chromosome 18

24
Q

Which trisomy causes Patau syndrome?

A

trisomy of chromosome 13

25
Q

What tests can be used to detect trisomies?

A

Fluorescent in situ hybridisation

and karyotyping

26
Q

What is non-disjunction?

A

the failure of homologous chromosomes or sister chromatids to separate properly during cell division

27
Q

Characteristics of Down’s syndrome

A
  1. facial dysmorphology
  2. IQ less than 50
  3. life expectancy of 50-60 years
28
Q

Characteristics of Edward’s syndrome

A

severe developmental problems- most will die within first year and many die within the first month

29
Q

Characteristics of Patau syndrome

A
  1. multiple dysmorphic features and mental retardation

2. about 5% die within the first month

30
Q

What is Turner’s syndrome?

A
  • a sex chromosome aneuploidy syndrome
  • 45, X
  • females of short stature and infertile
  • neck webbing and widely spaced nipples
  • intelligence and lifespan normal
31
Q

What is Kleinfelter syndrome?

A
  • a sex chromosome aneuploidy syndrome
  • 47, XXY
  • males of tall stature with long limbs
  • mild learning difficulties
  • infertile with small testes
32
Q

What are nucleosomes?

A

DNA is packaged with histones to form chromatin
DNA backbone is negative and histones are positive and so the DNA wraps itself around a core of 8 histones like beads on a string
these units of chromatin wrapped up are called nucleosomes

33
Q

How many chromosomes are there in each human cell?

A

46

34
Q

What is Fluorescence In Situ Hybridisation?

A

a laboratory technique for locating a specific DNA sequence on a chromosome - may be a gene
expose chromosomes to a small DNA sequence called a probe that has a fluorescent molecule attached to it

35
Q

What are centromeric probes useful for?

A

determining chromosome number

36
Q

What are telomeric probes useful for?

A

useful for detecting subtelometric rearrangements

37
Q

What are whole chromosome probes useful for?

A

detecting translocations and rearrangements

38
Q

What happens in meiosis?

A 
diploid cells (in ovaries and testes) divide to form haploid cells
chromosomes are passed on as recombined copies which creates genetic diversity
39
Q

Meiosis occurs in two phases to form 4 haploid cells. Describe what happens in each phase.

A

1st phase - when cells are lined up at the equator of the cell, homologous pairs of chromosomes cross over and exchange genetic information - forms 2 haploid cells
2nd phase - ordinary mitotic divisions which results in 4 haploid cells

40
Q

What is meant by ‘X linkage activation’?

A

in females there are 2 X chromosomes - in early embryo, there will be random inactivation of an X chromosome in each of the cells

41
Q

What kind of mutation is said to have occurred if there is no previous family history of cancer?

A

somatic

42
Q

What is ‘triploidy’?

A

when a zygote has a whole extra set of chromosomes (69 chromosomes)
this can be due to a number of factors but to give an example:
egg fertilised by 2 sperm therefore has 2 sets of father’s chromosomes and 1 set of mother’s
these zygotes do not tend to make it to full term

43
Q

What makes up a nucleotide?

A

ribose sugar, phosphate group, and base

44
Q

What is a nucleoside?

A

a nucleotide minus phosphate group

45
Q

Thymine is a…

A

pyramidine

46
Q

Adenine is a….

A

purine

47
Q

Guanine is a….

A

purine

48
Q

Cytosine is a…

A

pyramidine

49
Q

What is an oral contrast agent for CT?

A

dilute iodine based contrast to outline gastrointestinal tract

50
Q

What is an intravenous contrast agent for CT?

A

iodine based contrast - demonstrate blood vessels or vascularly different tissues

51
Q

What does MRI stand for?

A

Magnetic Resonance Imaging

52
Q

How does MRI work?

A
  • H+ atoms are randomly spinning but when a magnetic field is applied the atoms align themselves in the direction of the field
  • the H+ atoms will sign up so that they are either directed at the patient’s head or feet
  • there are some that will not arrange themselves in either way
  • a radiofrequency pulse is applied to the area of interest
  • non cancelled out H+ atoms will absorb the energy and start spinning again in a different direction
  • when radio frequency us turned off, the extra atoms will gradually return to normal position, emitting energy
  • energy turned into signal for computer which is covered to an image
53
Q

Advantages of MRI Imaging

A
  1. excellent bone/ soft tissue detailing

2. vessels can be demonstrated

54
Q

Disadvantages of MRI

A
  1. claustrophobic and noisy
  2. if you move, image can be ruined therefore lung imaging difficult
  3. cannot image patients with pacemakers or aneurysm clips
55
Q

What is the name of an MRI contrasting agent?

A

Gadolinium DTPA - IV contrast medium

56
Q

What does the use of Gadolinium DTPA make more easily seen in MRI?

A

vascular lesions and some tumours

Principles of Disease KR (4 decks)

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