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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
What tests can be used to detect trisomies?
Fluorescent in situ hybridisation | and karyotyping
26
What is non-disjunction?
the failure of homologous chromosomes or sister chromatids to separate properly during cell division
27
Characteristics of Down's syndrome
1. facial dysmorphology 2. IQ less than 50 3. life expectancy of 50-60 years
28
Characteristics of Edward's syndrome
severe developmental problems- most will die within first year and many die within the first month
29
Characteristics of Patau syndrome
1. multiple dysmorphic features and mental retardation | 2. about 5% die within the first month
30
What is Turner's syndrome?
- a sex chromosome aneuploidy syndrome - 45, X - females of short stature and infertile - neck webbing and widely spaced nipples - intelligence and lifespan normal
31
What is Kleinfelter syndrome?
- a sex chromosome aneuploidy syndrome - 47, XXY - males of tall stature with long limbs - mild learning difficulties - infertile with small testes
32
What are nucleosomes?
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
How many chromosomes are there in each human cell?
46
34
What is Fluorescence In Situ Hybridisation?
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
What are centromeric probes useful for?
determining chromosome number
36
What are telomeric probes useful for?
useful for detecting subtelometric rearrangements
37
What are whole chromosome probes useful for?
detecting translocations and rearrangements
38
What happens in meiosis?
``` diploid cells (in ovaries and testes) divide to form haploid cells chromosomes are passed on as recombined copies which creates genetic diversity ```
39
Meiosis occurs in two phases to form 4 haploid cells. Describe what happens in each phase.
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
What is meant by 'X linkage activation'?
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
What kind of mutation is said to have occurred if there is no previous family history of cancer?
somatic
42
What is 'triploidy'?
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
What makes up a nucleotide?
ribose sugar, phosphate group, and base
44
What is a nucleoside?
a nucleotide minus phosphate group
45
Thymine is a...
pyramidine
46
Adenine is a....
purine
47
Guanine is a....
purine
48
Cytosine is a...
pyramidine
49
What is an oral contrast agent for CT?
dilute iodine based contrast to outline gastrointestinal tract
50
What is an intravenous contrast agent for CT?
iodine based contrast - demonstrate blood vessels or vascularly different tissues
51
What does MRI stand for?
Magnetic Resonance Imaging
52
How does MRI work?
- 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
Advantages of MRI Imaging
1. excellent bone/ soft tissue detailing | 2. vessels can be demonstrated
54
Disadvantages of MRI
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
What is the name of an MRI contrasting agent?
Gadolinium DTPA - IV contrast medium
56
What does the use of Gadolinium DTPA make more easily seen in MRI?
vascular lesions and some tumours

Principles of Disease KR (4 decks)

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