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year 1 > principles genetics > Flashcards

principles genetics Flashcards

1
Q

what is a missense mutation

A

change of amino acid sequence

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2
Q

what is a nonsense mutation

A

new termination code

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3
Q

what is a silent mutation

A

no change of the amino acid sequence

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4
Q

what is a frameshift mutation

A

addition or deletion of a base

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5
Q

what kind of mutation is sickle cell anaemia

A

missense

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6
Q

what type of inheritance is sickle cell anaemia

A

co-dominant

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7
Q

what is klienfelters syndrome

A

3 sex chromosomes (47 XXY)

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8
Q

what is haemophilia A a genetic deficiency of

A

clotting factor VIII

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9
Q

what kind of inheritance is haemophilia A

A

X linked recessive but can be spontaneous mutation

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10
Q

are histones positively or negatively charged

A

positive

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11
Q

what is the DNA cycle

A

G1 - S - G2 - M - G1

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12
Q

what does mitosis produce

A

2 identical diploid daughter cells

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13
Q

what does meiosis produce

A

4 nonidentical haploid daughter cells

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14
Q

where does variation in meiosis come from

A

crossing over

independent assortment of homologous chromosomes

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15
Q

what occurs in G1

A

cell growth

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16
Q

when can mutation occur in the cell cycle

A

between G2 + M and GI + S

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17
Q

what / when is G0

A

between G1 and S

when cell functions normally and doesn’t replicate - most of life

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18
Q

when does DNA synthesis and replication occur

A

S phase

S for synthesis

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19
Q

what occurs during G2

A

DNA replication checked

2nd growth phase - involving proteins etc

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20
Q

what occurs during M

A

mitosis

m for mitosis

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21
Q

what can you see with Karyotyping

A

deletions of >5 million base pairings

looks at chromosomes as a whole

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22
Q

what is transcription

A

DNA to RNA

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23
Q

what is translation

A

RNA to protein

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24
Q

what are SNPs

A

single nucleotide polymorphisms

sequence changes in DNA between genes

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25
Q

what is a polymorphism

A

any variation in a human genome which has a population frequency of >1%
doesn’t cause disease in its own right but may predispose to a common disease

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26
Q

what is a mutation

A

DNA variant that causes or predisposes to a specific disease

any inheritable change in the human genome

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27
Q

what is a multifactorial disease

A

multiple polymorphisms cause a risk of disease - combine with environmental factors to cause disease
genes involved will have low penetrance

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28
Q

what is balanced chromosome rearrangement

A

translocation - usually normal

same amount of genetic information swapped - all chromosomal material is present

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29
Q

what is unbalanced chromosome rearrangement

A

translocation
extra or missing chromosomal material
usually 1 or 3 copies of some of the genome

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30
Q

what happens to the child if a parent has balanced chromosome arrangement

A

child inherits normal 2 copies + balanced = 3 copies

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31
Q

what is an acrocentric chromosome

A

centromere located very near the end of the chromosome

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32
Q

what is a telocentric chromosome

A

centromere located at terminal end of chromosome

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33
Q

what is epigenic variation

A

functional modifications to the genome that don’t involve a change in nucleotide sequence

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34
Q

what is aneuploidy

A

whole extra or missing chromosome

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35
Q

what is translocation

A

rearrangement of chromosomes

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36
Q

what is reciprocal translocation

A

segments from 2 different chromosomes have been exchanged

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37
Q

what is monosomy

A

missing chromosome from a pair

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38
Q

what is trisomy

A

extra chromosome in a pair

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39
Q

what is down syndrome

A

trisomy 21
47 XY
3 copies of 21

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40
Q

what can trisomy 14 cause

A

miscarriage

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41
Q

what is edward syndrome

A

trisomy 18

42
Q

what is turner syndrome

A

one sex chromosome

45 X

43
Q

what is robertsonian translocation

A

2 accrocentric chromosomes attach at centromere

only occurs with 13 14 15 21 22

44
Q

what is the most sensitive technique for looking for chromosomal imbalance (absent or duplicated material)

A

microarray CGH
can also find polymorphisms
if patient has extra DNA - predominantly red

45
Q

what is the best technique for looking for point mutations

A

PCR

46
Q

what is the best technique for looking at lots of genes

A

Next generation sequencing

47
Q

what is the best method for detection of plasma viral load in HIV patient

A

PCR

48
Q

what is the best method for measurement of T lymphocytes in blood

A

immunophenotyping

49
Q

what is the term to describe the presence of 2+ populations of cells with different phenotypes in one individual

A

mosaicism

50
Q

what is gonadal mosaicism

A

2 populations of cells in gonads one with a DNA mutation or chromosome anomaly

51
Q

what is somatic mosaicism

A

it is within the body cells so not passed on to children

post-zygotic mutation

52
Q

what genes stop cells dividing when switched on

A

tumour suppressors

53
Q

what genes start cells dividing when switched on

A

oncogenes

54
Q

what is cancer

A

mutations in a cell cause damage to control genes that allow cell to divide in uncontrolled fashion
normally atleast 3 different groups of cell with different phenotypes

55
Q

what is penetrance

A

the likelihood of having a disease if you have a gene mutation

56
Q

what is the term to describe variation in disease severity if you have the mutation

A

expression

57
Q

what are the mutations in CF

A

CFTR mutation

  • F508 deletion
  • G551D mutation
58
Q

what is the carrier frequency of CF

A

1/24 / 1/25

59
Q

what is the function of the CFTR gene

A

channel across membranes that produce mucus, sweat, saliva, tears, digestive enzymes
transports chloride ions out of the cell which indirectly controls the water movement allowing for thin free flowing mucus

60
Q

what happens when there are mutations in the CFTR gene

A

sodium is not pumped out into lumen/digestive/respiratory passages so mucus is think as water doesn’t enter areas

61
Q

what do mutations in the promoter and splice sequences cause

A

stop transcription or cause abnormal splicing

62
Q

what do base changing mutations cause

A

change in amino acid sequence
change in protein sequence
may / may not reduce protein function

63
Q

what is a mendelian disorder

A

a disease that is caused by a change in a single gene

64
Q

what diseases are considered mendelian

A 
autosomal dominant
autosomal recessive
X links
X inactivation
mitochondrial
65
Q

where is the disease seen in autosomal dominant

A

disease seen in all generations

66
Q

what is the risk of having an affected child in autosomal dominant

A

50%

67
Q

where is the disease seen in autosomal recessive

A

only one generation affected

68
Q 
if both parents are carriers of an AR disease what is the chance a child will be 
unaffected
not carriers and unaffected
affected 
carrier
A

unaffected - 3/4
unaffected and not carriers - 1/4
carrier - 1/2
affected - 1/4

69
Q

what do AR diseases usually cause

A

loss of function

70
Q

are X linked diseases recessive or dominant

A

recessive

71
Q

if a mother is a carrier of an XL disease what are the chances the daughter will also be a carrier

A

50%

72
Q

if a mother is a carrier of an XL disease what are the chances her son will be affected

A

50%

73
Q

what is X-inactivation

A

a cell only requires one working copy of the X chromosome so in females each cell has a random X chromosome inactivated

74
Q

a woman who is a carrier of a X linked haemophilia experiences haemorrhage following surgery
what is the most likely mechanism

A

normal X inactivation

50% of cells will have had normal X deleted so reduced capacity for blood clotting

75
Q 
the following s/s are s/s of what
myopathy
diabetes
deafness
optic atrophy
stroke like episodes
encephalitis
A

mitochondrial disease

76
Q

mitochondrial diseases are inherited almost exclusively maternally
true/false

A

true

77
Q

what is the term for the mutation where there is only one working copy which is not enough

A

haploinsufficiency

78
Q

what is the term for the mutation where an abnormal protein interferes with normal protein

A

dominant negative

79
Q

what is the term for the mutation where it activates a gene

A

gain of function mutation

80
Q

what happens when a polymorphism occurs in the promotor regions

A

less protein

81
Q

mendelian disorders have a high penetrance

true/false

A

true

82
Q

what does DNA methylation lead to

A

modification of histones which strengthens binding and so represses transcription

83
Q

what are 3 examples of non-mendelian inheritance

A

imprinting
angelman syndrome
heteroplasmy

84
Q

what is imprinting

A

differences in gene expression depending on whether a gene is maternally or paternally inherited

85
Q

what causes angel man syndrome

A

chromosome 15 fault

mother’s UBE3A works but fathers is methylated

86
Q

how does angel man syndrome express itself in the phenotype

A 
neuro-genetic disorder
developmental delay
intellectual disability 
ataxia
epilepsy
happy demeanour
frequent laughing and smiling
87
Q

what is heteroplasmy

A

different daughter cells contain different proportions of mutant mitochondria

88
Q

what are 5 characteristics gained by cells on progression to cancer

A 
Evasion of immune response
Acquire a vascular supply
Metastasis
Avoid apoptosis
Proliferation
89
Q

what is Li Fraumeni syndrome

A

mutation in p53 gene resulting in defective p53 protein

90
Q

what stage of the cell cycle may p53 halt in low O2

A

G2

91
Q

give 3 mechanisms of gene activation

A

duplication of the gene
activation of the gene promoter
change in amino acid sequence

92
Q

what does FISH stand for and what is it used for

A

Fluorescence in situ hybridisation
can light up a specific bit of chromosome if you know what bit to look for
can help identify aneuploidy or translocations etc

93
Q

mutations in BRCA1/2 gene cause a small proportion of what cancers

A

familial breast/ovarian cancer

94
Q

what is the BRCA1/2 gene involved in

A

DNA strand repair

95
Q

Philadelphia chromosome can cause leukaemia. what does it involve?

A

9 to 22 translocation

96
Q

the central dogma involves transcription, splicing, translation and post transcriptional modification
true/false

A

true

97
Q

A female patient is short and has mild learning difficulties. She has a lack of monthly periods and is infertile. What condition is most likely?

A

45X

98
Q

what is a metacentric chromosome

A

both arms of the chromosome are the same length

99
Q

what is the correct symbol for the short arm of a chromosome

A

p

100
Q

what disease best fits this phenotype

A female with normal intelligence and infertility

A

Turner’s syndrome

An individual with the normal number of autosomes, but only one X chromosome

101
Q

An individual with a balanced translocation between chromosomes 2 and 7, and two X chromosomes
what would the phenotype be

A

normal female

102
Q

what is progeria

A

a rare genetic condition causing growth retardation in infancy with macrocephaly and fast developing signs of old age caused by a spontaneous mutation

year 1 (45 decks)

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