1st & 2nd Year Genetics Flashcards
(121 cards)
1
Q
define genotype
A
genetic makeup
2
Q
define phenotype
A
genotype + environment
3
Q
describe the structure of a chromosome
A
central centromere, 4 chromatids (short arms and long arms), telomere cap
4
Q
how many chromosomes are the
A
46 (23 pairs)
5
Q
what is an acrocentric chromosome
A
centromere at 1 end of the chromosme
6
Q
how many acrocentric chromosomes are there in humans
A
5
7
Q
what is mitosis
A
cell division forming 2 diploid cells identical to the parent cells
8
Q
what is meiosis
A
cell division to 4 haploid games
9
Q
what causes variation in meoisis
A
independent assortment & crossing over
10
Q
how many base pairs are there in the genome
A
3,000,000,000 base pairs
11
Q
how many genes are the in human
A
30,000 genes
12
Q
what are the phases of interphase of the cell cycle
A
G1, G0, S phase, G2
13
Q
what are the phases of mitosis of the cell cycle
A
prophase, metaphase, anaphase, telophase, cytokenesis
14
Q
define nucleoside
A
base + sugar
15
Q
define nucleotide
A
base + sugar + phosphate group
16
Q
define nucleic acid
A
linked nucleotides
17
Q
name the bond between adjacent nucleotides
A
Phosphodiester bond
18
Q
where does DNA replication being
A
origin of replication
19
Q
what enzyme is responsible for unwinding the DNA strand in DNA replication
A
helicase
20
Q
what enzyme synthesises primers
A
primase
21
Q
what is the role of DNA polymerase in DNA replication on the leading strand
A
adds nucleotides to free 3’ end of template strand and
22
Q
what is the role of DNA polymerase in DNA replication on the lagging strand
A
replaces nucleotides with primers on lagging strand
23
Q
what is an oncogene
A
promote cell division
24
Q
give 2 examples of oncogenes
A
RAS, erb-B2
25
what is a tumour suppressor gene
inhibit cell division for DNA repair
26
give 3 examples of tumour suppressors
p53, BRCA, Rb
27
what is the promotor region
DNA region that initiates transcription
28
what is transcription
DNA -> mRNA
29
where does transcription occur
nucleus
30
what enzyme is responsible for transcription
RNA polymerase
31
how is transcription regulated
steroid hormones
32
what is splicing
pre mRNA -> mRNA, introns removed & exons remain
33
where does splicing occur
nucleus
34
what is an intron
non-coding DNA/RNA segment
35
what is an exon
coding DNA/RNA segment
36
what % of the genome do exons make up
2-3% of genome
37
what is a codon
3 nucleotides corresponding to 1 amino acid
38
what is translation
mRNA decoded by a ribosome -> polypeptide chain
39
where does translation occur
cytoplasm
40
what enzyme is responsible for translation
peptidyl transferase
41
what is the role of aminoacyl-tRNA synthetase
binds amino acids to their tRNA molecule
42
what is aminoacyl-tRNA
amino acid bound to tRNA
43
give examples of post-translational modifications
glycosylation, degradation, disulfide bonds, cleavage, methylation, phosphorylation, folding
44
where do post-translational modifications occur
free ribosomes in cytosol
45
where do co-translational modifications occur
bound ribosomes on RER
46
where are proteins from post-translational modifications for
cytosol, nucleus, mitochondria
47
where are proteins from co-translational modifications fo
membrane, ER, Golgi, secretion
48
define mutation
causes a genetic disorder or heritable change
49
define polymorphism
variation with population frequency >1%, doesn’t cause disease but may predispose
50
how many polyporphisms have been identified
>10 million identified
51
what does SNP stand for
single nucleotide polymorphism
52
how many SNPs does a person have
3 million/person
53
what is a point mutation
change in a single base
54
what is a missense mutation
changes amino acid sequence
55
what is a nonsense mutation
creates new stop codon
56
does a missense mutation affect protein function
it could
57
what is the effect of a nonsense mutation
changes length of protein
58
what is a silent mutation
doesn’t change amino acid
59
what is the effect of a silent mutation
no effect on function
60
what is a frameshift mutation
addition/deletion of a single base
61
what is a null mutation
no effective mRNA produced
62
what is a promotor mutation
no/reduced transcription
63
what is a trinucleotide repeat expansion mutation
codon repeated
64
what is a copy number variation
group term for unbalanced mutation
65
what is an inversion mutation
segment of chromosome copied in reverse order
66
what is a robertsonian translocation
acrocentric chromosomes stuck together
67
give an example of a robertsonian translocation
Down synd
68
what is a reciprocal translocation
exchange of material between non-homologous chromosomes
69
what is a balanced mutation
all chromosomal material present, not in correct arrangement
70
what is aneuploidy
extra/missing chromosome
71
what type of aneuploidy is better tolerated and why
X chromosome aneuploidy better tolerated (X inactivation)
72
what is somatic mosaicism
different genotypes in 1 set of chromosomes
73
what is a post-zygotic mutation
neither parent is mosaic but the child
74
what genetic tests are genomewide testing
aCGH, exome enriched NGS, whole genome sequencing
75
how many megabases are affected by chromosomal translocations
100
76
how many megabases are affected by deletions
10
77
how many megabases are affectd by microdeletions
5
78
what mutations can be identified by standard karyotyping
aneuploidy, chromosomal translocations, deletions
79
what mutations can be identified by aCGH
unbalanced chromosomal mutations; aneuploidy, chromosomal translocation, deletions, microdeletions
80
how does FISH work
highlights specific chromosomes/genes
81
what mutations are identified by FISH
small translocations, microdeletions & deletions
82
what is the function of PCR
amplifies small genetic changes allowing it to be sequenced
83
what is the process of PCR
Heated to 95, denatures DNA
Cooled to 55, primers anneal
Heated to 72, heat resistant Taq polymerase adds nucleotides, making 2 new identical stands
84
what occurs after DNA is amplified in PCR to show where a mutation is
sanger sequencing
85
are mendelian disorders high or low penetrance
high
86
what are the types of mendelian disorders
autosomal dominant, autosomal recessive, x-linked, mitochondrial
87
what is the risk of a child getting an autosomal dominant condition if 1 parent has it
50 percent
88
what is the risk of a child getting an autosomal recessive condition if 1 parent has it
25%
89
what are consanquineous families
incest
90
how will the offspring of a man with a x-linked condition be affected
all males affected, females carriers
91
what is heteroplasmy
proportion of mitochondria with mutation
92
inheritance pattern of mitochondrial diseases
maternally
93
what is x-inactivation
gene-dosage compensation, 1 active X chromosome
94
what is a mechanism of x-inactivation
methylation
95
are non-medialian disorders high penetrance
no
96
what is y linked inheritance
non-mendelian, male, infertile
97
what is a de-novo mutation
kid has it though parents don’t
98
what is imprinting
variation in gene expressed depending on parents its inherited from
99
give an example of imprinting and the affected gene
angleman syndome and chromosome 15 UBE3A gene
100
what is FGFR3 achondroplasia
dwarfism
101
what is trisomy 18
Edward synd
102
what is trisomy 21
Down synd
103
what is 45X
Turner’s synd
104
what is the presentation of turner's synd
short, low hairline, heart problem, OP, hypothyroid, lymphedema, primary amenorrhea, brachdactyly, infertile, +- breast development
105
what is 47XXY
Klinefelter’s synd
106
what is the presentation of klinefelter's
low testicular volume, undescended testes, infertile, gynaecomastia, intellect dysfunction, no sperm in semen
107
what is the Philadelphia chromosome
leukaemia, translocation
108
what is BRCA1
familial breast/ovarian cancer
109
what is Von-Hippel Lindau disease
inherited tumour disorder
110
define penetrance
likelihood of having disease if you have the mutation
111
what is the presentation of angelman synd
112
what is 4p16.3 microdeletion
Wolf-Hirschhorn synd
113
what is Kabuki synd
de novo MLL2
114
what test detects Wolf-Hirschhorn synd
array CGH
115
what test detects Kabuki synd
NGS
116
what is a driver mutation
mutations that drive carcinogenesis
117
what are pasenger mutations in cancer
incidental mutations since tumour is unstable
118
what is the 2 hit hypothesis
>2 copies of the functioning gene mutated for cancer to develop
119
what is a high risk patient for breast cancer
BRAC1 mutation
120
what is a medium risk patient for breast cancer
mother and sister with breast cancer age 45
121
what is a low risk patient for breast cancer
mother with breast cancer age 70
