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