genetics Flashcards
1
Q
what is a de novo mutation
A
mutation that arises for the first time in an individual
2
Q
what is fitness
A
the ability to pass on genetic information
3
Q
how do mutations effect an individual
A
mostly - neutral
some - deleterious
few - advantageous
4
Q
if you have 1000 people how many ales will you have
A
2000`
5
Q
what is the Hardy–Weinberg equilibrium
A
the relative frequencies of alleles between generations remains constant
unless changes
6
Q
assumptions with the hardy-Weinberg equilibrium
A
- mating is random
- migration is negligible
- no selection pressure
7
Q
what is natural selection
A
reduces reproductive fitness of an organism
8
Q
positive selection
A
increases reproductive fitness
9
Q
what is the founder effect
A
when a small sub set of a population (bottle necks) and forms a new colony with less allele variation
10
Q
what is genetic drift
A
widespread
natural
random by chance
11
Q
what types of non random mutations are there
A
assertive mating (smart with smart/ deaf with deaf)
consanguinity
marriage between close blood relatives
12
Q
how are genetic mutations classed
A
from 5 (being parthenogenic) to 1 being Benin)
13
Q
what are variants of uncertain significance
A
a mutation that cannot be determined to be either neutral or deleterious
14
Q
what is cultural isolation and example of
A
founder effect
15
Q
what is the the of DNA
A
the double helix and complimentary base pairing.
16
Q
what dose each nucleotide contain
A
sugar base and a phosphate
17
Q
where do transcription factors bind
A
on the major group
18
Q
why is the minor group not used
A
the proteins are too big to interact
19
Q
what dose the nucleolus do
A
make ribosomal RNA -
20
Q
what dose DNA wrap around
A
a histone
21
Q
what is a nucleosome
A
8 histones
22
Q
what is chromatin
what is the banding pattern
A
looks like a big bowl of spaghetti
all the DNA, proteins, RNA that make up a chromosome
due to the chromatin
23
Q
how is chromatin made more accessible
A
histones are modified by enzyme
24
Q
what way is replication
A
5’ to 3’ end
25
what bits are coding regions what are non coding
introns don't code
exons do code
26
what happens from dna to protein
```
DNA
transcription
mRNA,tRNA,rRNA
translation
protein
```
27
what is heterochromatin
Condensed structure
| Silenced genes
28
what is Euchromatin
Open structure
| Active genes
29
what are okazaki fragments
the fragments made as part of the lagging strand
30
what makes new DNA
DNApolymease
31
what binds the okazaki fragments
DNAlgase
32
what is the structure of a nucleosome
a solenoid structure
33
what one phat to analysed by photograph chromosomes
a karyotype
34
what is FISH
it is fluorescent in situ hybridisation
a piece of fluorescent probe DNA binds to its complementary section
35
what is Oogenesis
in the end what dose it make
process of egg formation
4 polar bodies and one egg
36
what is Spermatogenesis
what dose it make
process of sperm formation
4 sperm cells
37
what are examples of FISH probes
centromeric - chromosome No.
telomeric
whole chromosome probes - spectral karyotype
38
when dose recombination occur
prophase 1
39
what do two haploid cells form
a diploid - zygote which then becomes a embryo
40
what is maternal inheritance
the inheritance of mitochondrial DNA via the egg
41
what is x inactivation
when a sex linked allele i.e. is not on the y it is the only one expressed
however a female has to inactivate one x chromosome
42
what is autosomal inheritance
what are the two type
a pattern of inheritance that is not on a sex chromosome
dominant
recessive
43
what is sex linked inheritance
related to the sex chromosomes (it is a mutated x chromosome)
44
characteristics of sex linked
examples
no mail to male transmission
skip generations
only men affected
Duchenne muscular dystrophy
45
an arrow on a pedigree model shows
who you are doing this for
46
a line through someone means
deceased
47
a boy is
| and a girl is
square boy
| circle girl
48
what are the characteristic of autosomal dominant
examples
no skipped generations
male to male transmission
50% of inheriting the condition
Huntington's
dwarfism
49
what are the characteristic of autosomal recessive
examples
need both parents to be carriers
carriers can have symptom like presentation
cystic fibrosis
50
what are the 3 types of chromosomal abnormalities
numerical, structural and mutational
51
what are the majority of chromosomal mutations in the trimester and after birth
trisomy
52
what is trisomy
example
an extra chromosome - maternal origin
down syndrome
53
what is monosomy
example
only having one chromosome
turner 45,X
45 chromosomes not 46
lost a bit of x chromosome
54
what is trisomy 21
Down syndrome
1 in 650
Characteristic facial features
IQ less than 50
Average life expectancy (50-60 years)
55
what is trisomy 13
Patau syndrome
Multiple dysmorphic features and mental retardation
About 5% die within first month, very few survive beyond first year
56
what is turners syndrome
short stature infertile
| neck webbing - wide nipples
57
what is Klinefelter syndrome
```
47,XXY
1 in 1000
tall stature, long limbs
mild learning difficulties
small testes
```
58
when do partial trisomy and partial monosomy occur
when there is unbalanced translocation
59
what is Robertsonian translocation
Robert
loss of the short arms of a chromosome
60
what is the outcome of deletions
it depends on what was deleted
| variable outcome
61
what is the outcome of inversions
it depends on where and what genes are expressed on either side of the break
62
what is a unbalanced chromosomal change
when there is a duplicate of come DNA however there is not the full complement
63
what are the genetic mutation tyoes
germline or somatic
gene disruption / disease-associated
polymorphism
64
what are the types of coding mutations
silent - doesn't effect protein
missense - changes protein
nonsense - changes to a stop codon
frame shift - completely changes the outcome
65
what are the two type of point mutation
transitions - purine to purine
A to G
transversions - purine to pyrimidine
A to C
Cto G
66
what are detecting mutations
```
Polymerase chain reaction (PCR)
Gel electrophoresis
RFLP
ARMS
DNA sequencing
```
67
what are the 3 steps of PCR
Denature - 95oC
Anneal - 50-70oC
Extend - 70oC
68
what happens in gel electrophoresis
Separate DNA fragments by size
Apply an electric field
DNA is negatively charged
69
what are the advantages/disadvantages of arms
Cheap
Electrophoresis required
Limited amplification size
Limited amounts of product
70
what is the best way for detecting mutations
DNA sequencing
Automation and high throughput
Expensive equipment
71
what are microarrays
collection of microscopic DNA spots - seeing expression of gene
72
what is penetrance
the frequency with which a trait is manifested by individuals carrying the gene.
73
what is non-medilian inheritance
Several variants in several genes acting together
74
what are examples of non medeilian inheritance
```
Incomplete Penetrance
Genomic Imprinting
Extranuclear Inheritance
Complex
Anticipation
```
75
what is complex inheritance
when there are multiple low variants present
76
what is extran nuclear in heritance
what dose it effect
example
basically a mutation in the mitochondria
tissue with high metabolic demand
DAD
77
what is homoplasmy
uniform mtDNA
78
what is heterolasmy
two ore more types of mtDNA
79
what is anticipation
when a section of DNA that normally repeats is mutated
and repeats 50 times more
80
what is incomplete penetrance
when a phenotype does not manifest as the gene suggests
leading to a inaccurate pedigree without genetic testing
81
what is uniparental disomy
Inheritance of a chromosome pair from one parental origin
82
what is genomic imprinting
when there are genes expressed from only one parent and this goes wrong
83
what is PEG and MEG
paternally expressed gene, maternally expressed gene
84
Genetic drift
Random fluctuation of one allele transmitted to high proportion of offspring by chance
85
Founder effect
reduction in genetic variation that results when a small subset of a large population is used to establish a new colony
86
what are somatic mutations
non germline tissue
| are nonheritable
87
what are germline mutations
Present in egg or sperm
Are heritable
Cause cancer family syndromes
88
what are the 3 genetic processes associated with cancer
Oncogenes
Tumour suppressor genes
DNA damage-response genes
89
what do tumour suppressor genes have
a two hit hypothesis
90
what is a DNA response gene
it fixes a mismatch ie when two purines are together
MMR gene
91
what are MSIs
MSI is the phenotypic evidence that MMR is not functioning normally
92
examples of tumour suppressor genes
Rb
p53
BRAC1
93
examples of oncogenes
RET
| VEGF
94
what can a failure of mismatch repair gene do
lead do hereditary colorectal cancer
| CRC
95
what are the 5 classes of variant
```
5 = parthenogenic
1= benign
```
