more mcqs Flashcards
(196 cards)
1
Q
what do aminoacyl tRNA synthetases do?
A
catalyse the covalent attachment of amino acids to their corresponding tRNA molecules
2
Q
do aminoacyl tRNA synthetases have proof-reading activity?
A
no
3
Q
what allows viruses to initiate translation independently of the first AUG codon?
A
IRES
4
Q
what mediates binding of aminoacyl-tRNAs to the A-site of the ribosome?
A
elongation factor protein Tu
5
Q
what mediates 30S ribosomal subunit association with mRNAs in prokaryotes?
A
Shine-Dalgarno sequence
6
Q
what is TFIID?
A
a general transcription factor
7
Q
what is required for the synthesis of most rRNA precursors?
A
RNA polymerase I
8
Q
what is the TATA box?
A
a core promoter element
9
Q
what protein prevents parental DNA strands from re-annealing during DNA replication?
A
single strand binding protein
10
Q
what is DNA polymerase III?
A
an RNA-dependent DNA polymerase
11
Q
what is a bacterial enzyme that cuts DNA at/near specific recognition sequences?
A
restriction endonuclease
12
Q
what do aminoacyl tRNA synthetases do?
A
catalyse the covalent attachment of amino acids to their corresponding tRNA molecules
13
Q
how many DNA strands does Topoisomerase I cut?
A
single strand
14
Q
how many DNA strands does Topoisomerase II cut?
A
both strands
15
Q
what is an inherently error-prone double-strand break repair system?
A
non-homologous end joining
16
Q
what is a human genetic disease caused by mutations in p53?
A
Li-Fraumeni syndrome
17
Q
what is a human genetic disease caused by mutations in components of the nucleotide excision repair system?
A
Xeroderma pigmentosum
18
Q
what does increasing length do to the melting temperature of DNA?
A
increases it
19
Q
where do histones undergo post-translational modifications?
A
in their N-terminal sequences
20
Q
what does GR binding to its ligand result in?
A
translocation of GR to the nucleus
21
Q
what is the eukaryotic pre-initiation complex?
A
a set of specific DNA binding transcription factors bound to an enhancer element
22
Q
what is the chemical interaction that holds strands together in the DNA double helix?
A
hydrogen bond
23
Q
what is the chemical moiety at the 3’-end of a linear DNA molecule?
A
hydroxyl
24
Q
what aromatic base is normally paired with guanine?
A
cytosine
25
what is a transposon?
mobile genetic element
26
what is the DNA region at each end of a chromosome?
telomere
27
what enzyme initiates nucleic acid synthesis in DNA replication?
primase
28
what is a distinguishing feature of a lariat?
2'-5' phosphodiester bond
29
what is the core complex of RNAi?
RISC
30
what is the catalytic core of the spliceosome?
U2 and U6 snRNAs
31
what do base excision repair proteins do?
correct mismatch errors during DNA replication
32
when are RNA primers excised in DNA replication?
before ligation of the Okazaki fragments
33
how is CREB activated?
through cAMP dependent phosphorylation
34
what is transcription termination coupled to in eukaryotes?
mRNA polyadenylation
35
what is the packaging unit of chromosomal DNA in the nucleus of the cell?
nucleosome
36
what is a mutation in DNA that changes a purine nucleotide to another purine?
transition
37
what is the molecular basis of Huntington's disease?
triplet nucleotide expansion
38
what is at the 3' end of eukaryotic mRNA?
poly-A tail
39
what is the 5'-end of a nascent RNA transcript?
5'pppN
40
what is Rifamycin?
a potent RNA polymerase inhibitor
41
what mutational event would contribute most strongly to genetic instability and development of cancer?
loss of function of the MLH1 protein
42
what sort of mutations in tumor suppressor genes confer susceptibility to cancer?
inherited single allele mutations
43
what proportion of DNA on average would be shared between 2 half-siblings?
25%
44
which type of cancers tend to have more somatic mutations, adult or paediatric?
adult
45
can RNA hybridise with DNA?
yes
46
what is primase?
a DNA-dependent RNA polymerase
47
what is the heterogametic sex in birds?
females
48
what is the heterogametic sex in mammals?
males
49
does necroptosis require Tumour Necrosis Factor alpha?
no
50
what does necroptosis require?
RIPK3, MLKL
51
what can necrosulfonamide inhibit?
necroptosis
52
what does an IRES do in eukaryptes?
facilitates CAP-independent translation
53
what is transcription termination directly coupled to in eukaryotes?
mRNA polyadenylation
54
what protein is most strongly associated with an inherited predisposition to cancer?
RB
55
what protein is most strongly associated with development of B-cell lymphoma in chickens infected with the avian leukosis virus?
MYC
56
what protein is most strongly associated with tumour angiogenesis?
VEGF
57
what type of genetic variation is frequently caused by polymerase slippage?
Indel
58
what type of genetic variation is frequently caused by unbalanced structural variants?
copy number variant
59
what are transitions and transversions examples of?
single nucleotide variant
60
what is a type of DNA repair coupled to DNA synthesis?
mismatch repair?
61
what is a type of DNA polymerase-dependent DNA repair?
translesion synthesis
62
what is the type of repair associated with meiosis?
homologous recombination
63
what is the peak absorption wavelength of DNA?
260nm
64
what process has a speed which inversely corresponds to DNA sequence complexity?
strand reannealing
65
what is the assay to detect a specific RNA in a nucleic acid sample?
Northern blot
66
what is a sex chromosome aneuploidy condition in females?
Turner Syndrome
67
what is a sex chromosome aneuploidy condition in males?
Klinefelter syndrome
68
what condition is caused by paternal uniparental disomy for chromosome 15?
Angelman syndrome
69
what cell death process doesn't induce inflammation?
apoptosis
70
what type of cell death often depends on caspase 1?
pyroptosis
71
what type of cell death is induced by toxic lipid peroxides?
ferroptosis
72
what cells relate to the origin of adenocarcinomas?
glandular epithelial cells
73
how much of the euchromatic genome is composed of repeat sequences?
less than half
74
what do bacteria use DNA methylation for?
to control gene expression
75
what amino acid is ubiquitin covalently linked to?
lysine
76
what does canonical splicing require?
a large ribonucleoprotein complex
77
what does alternative splicing do to the diversity of the proteome?
increases it
78
can cells with unrepaired DNA become senescent?
yes
79
what sort of caspase is caspase 7?
executor
80
is an aneuploid karyotype always abnormal?
no
81
how many chromosomes does the mouse karyotype have?
40
82
what sort of sample sizes are used in GWAS?
large
83
what sort of disease variants do GWAS usually identify?
low risk disease variants
84
what protein is activated by genomic amplification in neuroblastoma?
N-Myc
85
what is the tumour virus protein responsible for binding to and inactivating p53?
HPV E6
86
what protein is regulated by intramolecular interactions with a phospho-tyrosine?
Rb
87
what is the region of attachment of 2 sister chromatids?
centromere
88
what is the functional effect achieved by X-chromosome inactivation?
dosage compensation
89
what is the DNA structure formed by telomeres?
G-quadruplex
90
what is the enzyme which unwinds the parental DNA in replication?
DNA helicase
91
what is the proof-reading activity of DNA polymerases?
3'-to-5' exonuclease
92
what is a required step in maturation of bacterial Okazaki fragments?
Nick translation
93
what is the template of transcription in eukaryotes?
promoter
94
what is a chromatin-modifying enzyme?
histone acetylase
95
what is a cis-regulatory element that can be located far from the gene locus?
enhancer
96
what protein inhibits G1-CDK?
p16^INK4a
97
what protein kinase has activity critical for mitosis?
PLK1
98
what transcription factor regulates expression of proteins and enzymes required for S phase?
E2F
99
what is an individual composed of cells with different genotypes?
mosaic
100
what is the point where exchange of genetic information occurs between homologous non-sister chromatids?
chiasma
101
what event is a hallmark of apoptosis?
release of cyt c from the mitochondria
102
can Bid be cleaved by caspase 8?
yes
103
which host-cell protein is inactivated by the HPV E6 protein?
p53
104
what does the Rb protein do for cell cycle progression?
inhibits it
105
what do the strands of z DNA form?
a left-handed helix
106
how does nucleotide excision repair not operate
direct replacement of the damaged nucleotide
107
what does CREB do to activate transcription?
binds the CBP co-activator
108
what is TFIID a complex of?
TATA binding protein (TBP) and 9 other general transcription factors called TAFs
109
which X chromosome is the Xist non-coding RNA expressed from?
the one that will be inactivated
110
does the human Y chromosome have a pseudoautosomal region?
yes
111
what % of the mitochondrial genome makes functional gene products?
95%
112
are cells with a mixture of normal and mutant mitochondria heteroplasmic?
yes
113
what can elevated frequencies of monogenic disorders in a population be due to?
a founder effect
114
what % of genetic material do dizygotic twins have in common on average?
50%
115
which do genetic factors play a greater role in, schizophrenia or Parkinson disease?
schizophrenia
116
what is inhibited by the Rb protein?
E2F1
117
what is involved in the pathogenesis of Burkitt's lymphoma?
c-Myc
118
loss of function of what protein is responsible for some cases of hereditary colon cancer?
Msh2
119
what is the technique used to detect a specific DNA sequence by hybridisation of complementary strands?
gel electrophoresis
120
what is a chemical modification used by bacteria to protect their DNA from restriction enzymes?
methylation
121
what is a common type of DNA lesion caused by UV light?
double strand DNA break
122
what is the type of cell division that includes HR between parental chromosomes?
meiosis
123
what enzyme recognises the damaged DNA in BER?
DNA glycosylase
124
what is a distinguishing feature of a lariat?
a 2'-5' phosphodiester bond
125
what is the catalytic core of the spliceosome?
U2 and U6 snRNAs
126
what defines the translation start site in prokaryotes?
Shine-Dalgarno sequence
127
what is the standard approach for identifying genetic factors governing susceptibility to complex disease?
GWAS
128
what is the phenomenon whereby disease phenotype is increasingly severe with each new generation of affected individuals?
anticipation
129
what process causes genes to be expressed according to their parental origin?
uniparental disomy
130
what is a trinucleotide repeat expansion disease (not Huntington's)
spinocerebellar ataxia
131
what common complex disorder is associated with more than 50 different loci on a single chromosome?
type 2 diabetes
132
in what disease is the Philadelphia chromosome found inn 90% of individuals with the disease?
chronic myeloid leukaemia
133
what does an IRES facilitate?
CAP-ndependent translation in eukaryotes
134
what will make a cell less likely to undergo apoptosis?
increasing the concentration of Bcl-2
135
which Bcl-2 family proteins have BH3 domains?
all of them
136
what are all of the offspring produced by parthogenesis in a heterogametic female?
male
137
mutation in which gene would contribute most significantly to cancer development, K-ras, p53, EGFR, Akt protein kinase, angiostatin?
EGFR
138
protein involved in inherited pre-disposition to cancer?
c-Myc
139
protein closely associated with pancreatic cancer?
K-Ras
140
kinase that promotes cell survival?
c-Src
141
distinguishing feature of an mRNA 5' CAP in eukaryotes?
5'-5' nucleotide bond
142
what is the ubiquitin ligase?
a small ribosomal subunit
143
what amino acid forms the bond between ubiquitin and a target protein?
internal lysine
144
what sort of protein is DNA dependent RNA polymerase?
reverse transcriptase
145
what is a mitochondrial disease with matrilineal inheritance?
Friedrich Ataxia
146
what condition is XY individuals developing as phenotypic females?
complete androgen insensitivity syndrome
147
what condition is commonly caused by the presence of the Philadelphia chromosome translocation?
chronic myeloid leukaemia
148
what is an ultrasound test contributing to prenatal Down Syndrome diagnosis?
exome sequencing
149
what is the initiator of dosage compensation in female mammals?
Xist non-coding RNA
150
what organ can make but not use ketones?
liver
151
where does gluconeogenesis take place?
liver and kidney
152
difference in chemical formula of D-glucose and D-fructose?
they are the same
153
most stable conformation of the four bases?
planar- not puckered rings
154
what is histidine able to do in enzyme mechanisms?
act as an acid and a base
155
effect of fructose-2,6-bisphosphate on phosphofructokinase-1?
activates it
156
role of calcium activated PDH phosphatase?
stimulates PDH activity
157
what vitamin is used by amino transferases?
vitamin B6
158
what pathway is ornithine found in?
urea cycle
159
what is the electron donor for FA synthesis?
NADP
160
what is the acyl carrier group?
ACP
161
where is the final orientation of a plasma protein established?
endoplasmic reticulum
162
what is genomic amplification of N-Myc associated with?
childhood neuroblastoma
163
result of the expression of Programmed Death-ligand 1 (PD-L1) by tumour cells?
suppression of T cell dependent immune surveillance
164
what defines the start site of transcription in eukaryotic transcription?
the pre-initiation complex (PIC)
165
how many steps of transesterification are required in intron splicing?
2
166
what is the Rb protein (functional description)
a transcriptional co-repressor
167
what process is most likely to become defective during aging-related female infertility in mammals?
chromosome cohesion
168
what does Angelman Syndrome result from?
loss of a maternally expressed imprinted gene
169
cause of cerebrocortical necrosis in ruminants/Wernickes encephalopathy in humans?
net deficiency of thiamine
170
what is widely used as a perfusion imaging agent?
Gd-DOTA
171
amino acids that are exclusively ketogenic?
lysine and leucine
172
method used to find new protein interactions?
coimmunoprecipitation
173
gel based method used to detect presence of specific protein in a cell extract?
Western blot
174
enzyme with anaplerotic function in gluconeogenesis?
pyruvate carboxylase
175
enzyme which catalyses the NADH-generating step in glycolysis?
glyceraldehyde 3-phosphate dehydrogenase
176
enzyme which phosphorylates blood-supplied glucose in the brain?
hexokinase
177
primary enzyme for catalysing conversion of triglyceride to diacylglyceride?
ATGL
178
electron acceptor for acyl-CoA dehydrogenase?
FAD+
179
what is acetoacetate?
a ketone
180
main product of FA synthesis?
palmitate
181
what facilitates movement of acetyl-CoA from mitochondria to cytoplasm?
tricarboxylic acid transporter
182
what covalently regulates acetyl-CoA carboxylase?
AMPK
183
what organelle receives fully folded protein imported from cytosol?
nucleus
184
where are sugar residues first attached to secreted proteins?
endoplasmic reticulum lumen
185
location of the Sec61 translocon complex?
endoplasmic reticulum membrane
186
what mediate recovery from receptor activated intracellular signalling?
Ca2+ pumps and cyclic nucleotide phosphodiesterases
187
what activates protein kinase C?
diacylglycerol
188
what is a lesion recognised by nucleotide excision repair?
cyclo-pyrimidine dimer (CPD)
189
what is an enzyme of base excision repair?
DNA glycosylase
190
what is an initial step in the process of double strand break repair?
DNA-end resection
191
what can arise from nondisjunction of the X and Y chromosomes in meiosis I?
Turner syndrome
192
what can arise from mutation of the SRY gene?
Swyer syndrome
193
what can arise from uniparental isodisomy of chromosome 7?
cystic fibrosis
194
what is the term for the degree to which a phenotype manifests in an individual carrying a particular genotype?
expressivity
195
what is the state occurring when cells derived from 2 different fertilised eggs co-occur in the same body?
chimerism
196
what is the state whereby contribution of both alleles is visible in the heterozygous phenotype?
co-dominance
