genetics Flashcards
1
Q
what are pathological polymorphism
A
mutations
2
Q
what is PCR
A
ability to amplify a small amount of DNA millions of times
3
Q
what is a DNA probe
A
piece of single stranded DNA that can locate and bind to its complementary sequence
4
Q
what is hybridisation
A
when thousands of probes are analysed
5
Q
what is PCR
A
when a primer acts as a starting point for DNA polymerase to build a new DNA chain that is complimentary to the sequence under investigation
6
Q
what do single nucleotide polymorphs consist of
A
two nucleotides at a particular site
7
Q
what chromosome is the cystic fibrosis gene on
A
chromosome 7
8
Q
what is DNA wound around
A
histone proteins
9
Q
what is DNA + histone called
A
nucleosome
10
Q
how many chromosomes in human cell
A
46
23 inherited from each parents
11
Q
what sex chromosome do males have
A
XY
12
Q
what sex chromosome do females have
A
XX
13
Q
what is the middle of chromosome called
A
centrosome
14
Q
what is the short arm
A
p
15
Q
what is the long arm
A
q
16
Q
when can chromosome be stained
A
in metaphase
17
Q
where exactly is the CFTR gene
A
chromosome 7 on band 21
7q21
18
Q
what occurs in mitosis
A
each chromosome divides into 2 daughter cells
19
Q
what happens to the X chromosomes in a female
A
X inactivation that is random
it can affect either X chromosomes
20
Q
what is at the end of a chromosome
A
telomeres contain many repeats of TTAGGG
21
Q
what are the ends of the chromosomes susceptible to
A
single-stranded DNA degradation back to double-stranded DNA
22
Q
what happens to the ends of telomeres when they differentiated
A
they get shorter
23
Q
what happens to germ cells when they replicate
A
they do not shorten as they have telomerase
24
Q
what is telomerase
A
protects against telomere shortening by acting as a template primer
25
what do cancer cells switch on to become immortal
telomerase
26
how many pairs of chromosome in a human
23
27
what is the mitochondrial chromosome
circular DNA
28
what does mitochondria produce
ATP
29
what else do mitochondria have a critical role in
apoptotic cell death
30
where are all mitochondria inherited from
mother
31
is somatic inherited
no
32
what do somatic cell mutation give rise to
tumours
33
what is aneuploidy
whole extra or missing chromosome
34
what is non-dysfunction
chromatid or chromosome fails to separate
35
what is an extra chromosome called
trisomy
36
what is having only one chromosome called
monosomy
37
what is trisomy 21
Down syndrome
38
what abnormalities cause klinefter
XXY
39
what is it called when individual only have one chromosome monosomy X or Y
Turner syndrome
40
what do micro deletions in chromosome 22 give rise to
DiGeorge syndrome
41
what do inversions involve
end to end reversal of a segment within a chromosome
42
example of disease caused by inversion
haemophilia
43
what is translocation
two chromosome regions join together
44
what is a reciprocal translocation
two non-homologous chromosome break simultaneously and rejoin
45
what is robertsonian translocation
two acrocentric chromosome join
short arm is lost
46
what is risk of passing on robertsonian translocation
children may have unbalanced
47
what mutation causes down syndrome
trisomy 21
48
clinical features of Down syndrome
- flat face
- slanting eyes
- small ears
- short and stubby fingers
- learning difficulties
etc
49
what is trisomy 13 cause
patau syndrome
survive few weeks
50
what does trisomy 18 cause
edwards syndrome
51
clinical features of Edwards syndrome
- low set ears
- rocker bottom feet.
- learning difficulties
52
who does turner syndrome affect
women
53
what mutation cause turner syndrome
45 X
54
clinical features of turner syndrome
- infantilism
- short stature
- webbed neck
55
who gets triple X syndrome
women
56
who gets klinefter syndrome
men
57
what mutation cause klinefter syndrome
47 XXY
58
clinical features of klinefter syndrome
- decreased crown pubis
- testicualr atrophy
- infertility
- gynaecomastia
- learning difficulties
59
what are most mitochondrial disease
myopathies and neuropathies
60
what else does mitochondrial disease cause
- retinal degeneration
- diabetes mellitus
- hearing loss
61
what is most common cause of blindness in young men
leber's hereditary optic neuropathy
62
what detects imbalances
array CGH
63
what environmental causes can lead to mutations
- radiation
- ultraviolet light
- chemicals
64
what is point mutations
substitution of one nucleotide for another
65
example of disease caused by point mutation
sickle cell anaemia
66
what is the change in sickle cell anaemia
GAG to GTG
67
when is insertion or deletion more malicious
if the insertion or deletion are a multiple of 3 bases as it causes the sequence to be out of frame
68
what can splicing mutations lead to
alter amino acid composition
69
what is a nonsense mutation
point mutation in a sequence of DNA that results in a premature stop codon
70
what is autosomal dominant disorder
occurs when one of the two copies has a mutation
71
what are the chances of offspring inheriting disease in heterozygotes
50% chance of inheriting the chromosome
72
what are the parents in an autosomal recessive disorder
both unaffected carriers
73
autosomal recessive:
| if carriers marry with are the chances of kids being a carrier or affected
1 in 4
74
X-linked:
| what are the chances an affected mother will pass it on
half the male or female offspring will be affected
75
X-linked:
| what are the chances an affected father will pass it on
all female will be affected
76
example of X-linked recessive disorder
haemophilia A
77
what will the male offspring of a male with haemophilia and a normal female be
male will not have the disease as they do not inherit their X chromosome form their father
78
what is the inheritance of mitochondrial disease
incomplete penetrance maternal inheritance
79
what is the altered gene in Angelman syndrome
UBE3A
80
what are mutations used by multiple genes termed
polygenic
81
what is risk of being affected by chromosomal abnormalities
low
82
what is risk of being affected by mendelian disorder
high
83
when does the risk of down syndrome increase
in mothers over the age of 35
84
what is done at 7-11 weeks for prenatal screening
ultrasound to confirm viability, fatal number and gestation by crown-rump measurement
85
what is done at 11-13 weeks for prenatal screening
- ultrasound to detect major chromosomal abnormalities
| - testing of maternal serum for pregnancy associated plasma protein
86
what test are done at 14-20 weeks for prenatal screening
- testing maternal serum
| - quadruple test is to measure inhibin A
87
what does it mean if inhibin A is high
down syndrome
88
what test are done at 14-22 weeks at prenatal screening
- ultrasound detects structural abnormalities
89
when is best time to detect congenital heart defects
18-22
90
what are the mutations in cystic fibrosis
F508del
91
what does mutation in F508del cause
CFTR protein is misfiled, causing ineffective biosynthesis therefore disrupting the delivery of the protein to the cell surface
92
what other mutation can cause cystic fibrosis
G551D
93
what does mutated G551D cause
the channel to not open properly
94
what is apoptosis
programmed cell death
95
what are the mutation in cancer
somatic
96
what is retinoblastoma cancer
eye tumour in younger children
97
what tumours are likely to develop with eye tumour
osteosarcoma
98
what are 2 major genes that are mutated in breast cancer
BRCA1
| BRCA2
99
what are oncogenes
those that promote cell growth
100
point mutation in KRAS can cause
- colorectal cacner
| - pancreatic cancer
101
point mutation in BRAF can cause
- melanoma
| - thyroid
102
point mutation in ALK can cause
lung cancer
103
DNA amplification of MYC can cause
neuroblastoma
104
DNA amplification of HER2 can cause
breast cancer
105
chromosome translocation between BCR and ABL can cause
- chronic myeloid leukaemia
106
chromosome translocation between PML and RARA can cause
leukaemia
107
chromosome translocation between Bcl2 and IGH can cause
follicular lymphoma
108
chromosome translocation between MYC and IgH can cause
Burkitt's lymphoma
109
examples of where carcinogens can be found
- cigarette smoke
- ionising radiation
- UV light
110
what can carcinogens cause
point mutation in genomic DNA
111
what do tumour suppressor do
restrict undue cell proliferation
112
what can mutation in tumour suppressors cause
uncontrolled cell growth
113
example of tumour suppressor
p53
114
in what tumours have p53 mutations been found
- colorectal
- carcinomas of breast and lung
- brain tumour
- osteosarcoma
- leukaemia
115
Oncogene examples
Ras
| Myc
116
Tumour suppressors
p53
APC
BRCA 1/2
Rb
