More Old MCQS Flashcards
what effect does increased ATP have on insulin secretion?
increases it
can peptide bonds involving proline residues act as hydrogen bond acceptors?
yes
is formation of a peptide bond exergonic or endergonic?
endergonic
what gives the C-N bond in peptide bond double bond characteristics?
electrons from the N atom of the bond delocalising into the bond
what is normal BMI range?
18.5-25
what is normal blood glucose range when fasting?
3.9-5.5
what is normal blood glucose range when fed?
below 7.8
do allosteric enzymes display michaelis menten kinetics?
no
is insulin a glycoprotein?
no
what enzymes is allostery usually associated with?
multi-subunit
what effect does ATP have on PFK?
inhibits it
what effect does fructose 2,6-bisphosphate have on PFK-1?
activates it
what are the H bonds between in alpha helices?
residue i and residue i+4
what secondary structure are the haemoglobin subunits mainly composed of?
alpha helices
does lowering pH stabilise the deoxy form of haemoglobin?
yes
what level of 2,3- bisphosphoglycerate stabilises the oxy form of haemoglobin?
low
what causes sickle cell anaemia?
replacement of a glutamine residue with a valine in the beta subunit
which amino acid is acetylated in histones?
lysine
which amino acid can be transaminated to form oxaloacetate?
aspartate
what is standard molar free energy change equal to?
-RTlnKeq
what angles are alpha helices associated with?
dihedral
what is an enzyme that is inhibited by citrate and ATP?
PFK
what is an enzyme present in mitochondrial matrix that is inhibited by phosphorylation and activated by insulin?
pyruvate dehydrogenase
what is an enzyme in liver that is inhibited by glucagon and alanine?
pyruvate kinase
is phosphorylation a covalent modification?
yes
what does penicillin inhibit?
glycopeptide transpeptidase
which type of diabetes are ketosis and acidosis more common in?
type 2
what is the Φ (Phi) bond between?
the N and the alpha C
what is the Ψ (Psi) bond between?
the alpha C and the carbonyl C
can gel filtration separate proteins in their native conformation?
yes
does gel filtration separate proteins according to their native charge to mass ratio?
no
does penicillin form a covalent bond with an essential amino acid residue in the active site of its target enzyme?
yes (serine)
does insulin contain intramolecular disulphide bonds?
yes
can calcium ions activate pyruvate oxidation in the CAC?
yes
what is an enzyme that catalyses phosphorylation of other enzymes?
PFK
what is an enzyme activated as a consequence of insulin-induced dephosphorylation?
glycogen synthase
what is an integral membrane protein whose inhibition leads to stimulation of insulin secretion?
atp-sensitive potassium channel
where does fatty acid biosynthesis occur?
cytoplasm
what circumvents the energy barrier between PEP and pyruvate?
oxaloacetate
which amino acid is associated with immune function?
vitamin A
what is the function of glycogen phosphorylase?
catalyses glycogen breakdown
what does fatty acid synthase do?
catalyses FA synthesis
what does isocitrate dehydrogenase do?
catalyses breakdown of isocitrate in the CAC
what does pyruvate dehydrogenase do?
catalyses conversion of pyruvate to acetyl coA
what does pyruvate kinase do?
catalyses last step of glycolysis
what does phosphofructokinase do?
catalyses fructose 6 P to fructose 1,6 bisP in glycolysis
does insulin have 2 subunits encoded by different genes?
no
is insulin a glycoprotein?
no
is insulin a phosphoprotein?
no
is insulin cleaved into 2 portions after secretion?
no
is allostery mainly associated with multi or single-subunit enzymes?
multi-subunit
what is the effect of ATP on PFK?
inhibits
what is the effect of F 2,6-bisp on PFK?
activator
what residues are the H bonds between in alpha helices?
residue i and i + 4
are all alpha helices amphipathic?
no
do the side chains in alpha helices project inwards or outwards?
outwards
what is the cause of sickle cell anaemia?
replacement of a Glu residue with a Val in the beta-subunit
is the oxy form of haemoglobin stabilised by binding to 2,3 bisphosphoglycerate?
no
what is the precursor of ketone bodies?
acetyl-CoA
what does Complex II require to oxidise succinate?
FAD
do uncouplers inhibit respiration?
no
would inhibitors of glucokinase be helpful in treatment of hyperglycaemia and diabetes?
no
would inhibitors of glycogen synthase be helpful in treatment of hyperglycaemia and diabetes?
no
would inhibitors of phosphoinositide kinases be helpful in treatment of hyperglycaemia and diabetes?
no
would inhibitors of phosphotyrosine kinases be helpful in treatment of hyperglycaemia and diabetes?
yes
would inhibitors of protein-tyrosine kinases be helpful in treatment of hyperglycaemia and diabetes?
no
what is PKA composed of?
catalytic and regulatory subunits
what sort of protein is the glutamate kinate receptor?
a ligand-gated ion channel
what enzyme is activated as a result of insulin-induced dephosphorylation?
glycogen synthase
what is an integral membrane protein whose inhibition leads to stimulation of insulin secretion?
ATP-sensitive potassium channel
what is a substrate for cAMP synthesis?
ATP
what substrate is required for conversion of oxaloacetate to PEP?
GTP
what substrate is needed for the elongation of glycogen chains?
UDP-glucose
what type of compound might be useful in treatment of hyperglycaemia and diabetes?
inhibitors of phosphotyrosine phosphatases
what is PKA composed of?
catalytic and regulatory subunits
is glutamate kainate a ligand-gated ion channel?
yes
what substrate is responsible for the conversion of oxaloacetate to phosphoenolpyruvate?
GTP
what does insulin stimulate?
glycogenesis, lipogenesis, protein synthesis
what residues are cell surface oligosaccharides attached to?
serine, threonine, lysine, arginine
what do Asn, Gln and Ser all have in common?
all polar
what doe Leu, Ile and Val all have in common?
all branch chain hydrocarbons
what does Trp, Tyr and Phe all have in common?
aromatic
what do Tyr, Ser and Thr all have in common?
all hydroxyl groups
what is the affinity for the substrate of an enzyme with a high Km?
low
what is Kcat?
the turnover number of an enzyme
what are Leu zipper domains made of?
2 helices that each bind to a DNA major groove
what do PTB and SH2 domains both bind to?
phosphorylated tyrosines
what does the PH domain bind to?
inositol phospholipids for membrane recruitment
what inhibits the Raf catalytic domain?
the N-terminus of the Raf protein
what does phage display involve?
using a phage particle expressing the antigen to screen antibodies
what is the role of the neonatal Fc receptor?
prevents degradation of IgG
what does isocitrate dehydrogenase do?
catalyses the decarboxylation of isocitrate to alpha-ketoglutarate.
which has a higher Km for glucose, glucokinase or hexokinase?
glucokinase
which type of reaction involving DNA polymerase will be most error-prone?
DNA repair
which regions of the human genome is the TTAGGG repeat associated with?
telomeres
is the Pribnow box an important determinant of the transcription start site? (this is the true answer)
yes
which amino acids forms an isopeptide bond with ubiquitin C-terminus?
lysine
which structure is essential for the degradation of long-lived proteins?
lysosome
what do the chromosomal translocations characteristic of non-AIDS Burkitt’s lymphoma involve?
the c-Myc gene
what proteins does the APC/C CDH1 degrade to regulate Mcm2-7 helicase loading?
geminin
what does Ribociclib target?
CDK4/CDK6
is caspase activation needed for cell death induced by MOMP?
no
how is MOMP regulated?
by the balance between pro- and anti-apoptotic members of the Bcl-2 family
where do caspases cleave?
after Asp residues
cofactor used by succinate dehydrogenase?
FAD+
allosteric inhibitor of PFK-1?
citrate and ATP
cofactor of the E1 component of the PDH complex?
thiamine pyrophosphate
what liberates iron from Fe-S clusters?
superoxide dismutase
what accepts electrons from complex 1?
ubiquinone
what accepts electrons from conversion of succinate to fumarate?
succinate dehydrogenase subunit A
what mediates recovery from receptor activated intracellular signaling?
Ca2+ pump and cyclic nucleotide phosphodiesterase
what activates protein kinase C?
DAG
what is the chain-terminating nucleotide used in Sanger sequencing?
dideoxynucleotide (ddNTP)
what is a type of DNA damage that can be directly reversed by a photolyase enzyme?
thymidine dimer
what is a modified base commonly found in bacteria that protects the DNA from restriction enzyme cleavage?
N6-methyladenine
what is an enzyme with reverse transcriptase activity?
telomerase
enzyme that resolves intertwined DNA molecules at converged replication forks in replication termination?
topoisomerase II
enzyme that initiates DNA synthesis in bacterial replication?
DnaG primase
example of a non-receptor tyrosine kinase?
SRC
example of a small protein that hydrolyses GTP?
Ras
endogenous mutational process that causes SNV mutations?
spontaneous deamination
cluster of defined alleles inherited together?
haplotype
type of genomic variation associated with trinucleotide repeat expansion disorders?
indel variant
enzyme regulating centrosome duplication?
cyclin E/Cdk2
protein component of the mitotic spindle?
tubulin
enzyme required to remove sister chromatid cohesion?
separase
nuclear volumes occupied by interphase chromosomes?
chromosome compartments
self-interacting chromosome regions?
topologically-associating domains
main microtubule organising centre?
centrosome
complex required to attach chromatids to the mitotic spindle?
kinetochore
kinase complex with activity required for entry into mitosis?
Cdk1/Cdh1
protein frequently activated in pancreatic carcinoma
KRAS
what is necessary for GWAS to work but hampers identification of causal variants?
linkage disequilibrium
protein that degrades cAMP?
phosphodiesterase
enzyme that phosphorylates PET tracer FDG to metabolically trap it?
hexokinase
molecule that is imaging agent used for dissolution dynamic nuclear polarisation?
[1-13C]p pyruvate
what does pyroptosis require?
Gasdermin D, caspase 1
how do replicative helicases unwind DNA?
by steric exclusion
how are the alpha-helices forming a Greek key motif held together laterally?
by main-chain H bonding
what drives DNA replication?
hydrolysis of the bond between the alpha and beta phosphates of the deoxy nucleotide triphosphates
